Did Liars and Thieves Misdiagnose this Car or Am I the Bad Guy
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- čas přidán 21. 08. 2024
- 2007 Jeep Commander with misfire issue that two shops were unable to diagnose, but they had no problem finding just about everything else wrong with the car. So the owner brought it to me to help out.
I've owned a shop for 15 years.
You are spot on. We operate with old school morals and ethics.
I turn away roughly 20 people per day. And my customers won't go anywhere else.
Honesty is easy and WILL make the money flow.
Bravo!!!!!!
Location please
Denver Colorado
He’s back !!
God bless you for not charging them, and the good video
Well Matt, I've left you a few comments before. I'm almost 73 now. I have 2 hobbies, watching your videos and bowling. 25 - 300's. Looks like I'm gonna sign up to your channel. Tell me how to enlist. You are the GREATEST. And yes. I yelled " GREATEST " !!!
Hahah thanks so much. By the way I worked at a bowling alley when I was 15. Was there for 13 years. Never bowled a 300. 279 is my best. I never seen anyone bowl 25 300’s but I remember watching a guy bowl a 898 series.
Well, compression test you get a very brief blast of air/pressure on the leaky section of the gasket. Leak down test is a consistent pressure being held on a weak gasket.
Love how you’re precise and the fact you’re not trying to mess people over.
VERY SMART MAN
Matt, I agree, when I was working as a tech, my philosophy was always "If you pay more attention to helping the customer than what it pays, your paycheck will take care of itself". My goals were always fixing the car right or leaving it in the same condition it was when it rolled out of the factory.
How funny because I have used a nearly identical version of that with my clients for my real job. “If you take care of your clients, they take care of your numbers”.
It’s a great philosophy! Glad to see someone else who owns it too!!
I think of the car, not who's driving. I think of drivers driving home:)
A few suggestions:
For the voltage relative compression test, set the channel to AC coupling, reduce voltage to something more like +/-2V, whatever is suitable. Should make the variations far more obvious.
For the amp clamp relative compression test, use filtering to remove most of that noise. Noise can hide lots of details. Again, AC coupling may also improve the situation, or not - try it and see.
For additional tests, try a pressure pulse sensor or pressure transducer connected to the cooling system. You should see when the cooling system pressure increases = when one cylinder leaks into the cooling system. Add a sync signal from #1 ignition for example and you'll see which cylinder is leaking.
If you put a pulse sensor or a pressure transducer connected to your pico into the coolant neck, you might see a small pressure increase when the bad cylinder is on compression. This should work because you had pressure in there after cranking when you took the cap off. If there is a misfire, you can put them in the exhaust aswell. This would be very helpful to pinpoint which cylinder to test if there was no misfire data.
great recommendation!!!
You got here first. This should pick up the pressure pulses going into the cooling system. Might be more accurate with a pulse sensor.
Please do a follow up if possible. Would be great to see.
Came here to say this too! Sync it with a coil or fuel injector and you can locate the exact problem cylinder. It works with either a regular transducer or a first look type pulse sensor. Super quick, accurate and easy.
@@NZdiagnostics GREAT ADVICE , BUT ALWAYS SINC TO THE COIL NOT THE INJECTOR , INJECTOR FIRE BEFORE AND AFTER INTAKE VALVE OPENS AND CLOSES SO IT'S NOT TRUE TDC. THE COIL TIMING WILL BE MORE ACCURATE.
Matt dropping some red pills in this one. Thieves = admired. Honest = suspicion.
That's how you achieve "equity".
I used to work for Caterpillar global engine development testing engines. We used in cylinder pressure transducers to monitor cylinder pressure while the engine was running. We did this to monitor knock while advancing timing. Anyways... The pressure developed during combustion is much higher than that developed by just cranking the engine. If the head gasket is minimally compromised it may not show on a simple compression test. Cylinder pressure during combusting will be much higher and be enough higher that it produces the symptoms of a blown HG. I've seen this on diesel engines several times. All the symptoms of a blown HG... Compression test normal. This is even more disturbing since diesel engines typically make in excess of 400psi during normal cranking. I've seen several diesel engines with blown HG run mostly normally and never over heat either. The only real indication is excess pressure in the cooling system. Good video 👍
Yes a honest person with a conscience. Great job. You make Great videos. You have a wealth of knowledge that you share with us. Thank you.
thanks for the nice comment!
There is a better way, but only on cars that support individual cylinder misfire data. You will get a misfire on that cylinder on cold start, most newer cars have a misfire counter for each individual cylinder and that will help point you where you should be doing a leakdown on. If there is no "misfire" data, some vehicles tell you the speed variation of the crankshaft per each cylinder you can go off of that. But older cars you simply won't get that data as it isn't programmed in to tell you what cylinder is misfiring. Relative compression like you said is sometimes fruitless, because a head gasket leaking into a coolant jacket usually doesn't cause a significant loss of compression, its simply coolant being sucked in on the intake stroke.
Your P0307 is basically your pointer already. But sometimes its nice to verify misfire in live data via the counter. Because it won't always trip the code.
Good advice. I am actually aware of this but haven’t introduced concept in videos yet. Maybe time to do that.
Great video Matt! Flat rate master did a pretty cool video about head gasket testing and he mentioned an interesting method of pressurizing the cooling system and looking in the cylinder with one of those endoscopes for the appearance of wetness on top of the pistons......thought that was a pretty neat idea.
I think you did a great job, and I hope this person becomes a great customer for you in the future. I feel like you do, treat people honestly, you will sleep much better at night. My wife gets so angry with me because at 73 with a bad back and shoulders I do everything myself, I told her "I would love to pay someone competent a great wage to fix things for me , but every time I do that, they do not do the job correctly, or they skip steps for a few dollars and it looks crappy or only lasts a short time.
Awesome video Matt, glad you're back. I always thought that a cylinder pressure test was the answer for compression problems but I stand corrected so thanks again for PROVING it on video and pointing out a better way to diagnose that type of problem. I don't mind putting in the work if the results are correct and by the way I share your views on the current declining status of our American values
So glad to hear - on all counts!!!
Yeah I don’t mind admitting I am wrong and my reliance on compression tests earlier on was indeed an oversight. It can be misleading.
Rest assured you didn’t steel the customer, the other shops all but forced them to you.
You’re such an inspiration to all of us. Thank you for talking through the thought process of being a good human.
Good way of looking at it!!
I am just like José, I mean learning out of passion form guys like you and Scannerdanner. I learnt alot.
There is many of us, Josés, out there appreciating your work.
Thank you.
I am very aware of that!!! In fact I make this channel EXACTLY for you guys!!! You are the target audience I have always aimed for.
@@SchrodingersBox WE LOVE YOU! 🙌🏻
Hahaha love you all too!!! I really do!!
I have worked at a couple shops over the years and it doesn't suprise me that they look over the whole car. I remember the franchise would make us fill out these forms for every car that came in. I would feel sorry for the customer that just wanted an oil change and got a qoute for 1000 worth of work. Anyways, I just do this to help people out and make a little extra money now. I love watching these videos and learning about all the new tools that come out. I just bought an inspection camera from the big A for 100 and I was floored by how clear the video is and it has a side view camera. I would bet that if you pulled the spark plugs and looked in the cylinder with this camera you could see the staem cleaned piston right away. Thank you for the video!
Great comment. Yes it is hilarious to me when I see these write ups for thousands of dollars when the customer wants new tires or whatever. Sheeesh lol.
Yeah I totally which I borescoped the cylinder. Also the presence of enough coolant in the cylinder probably made it so it couldn’t be squeezed out and thus the compression didn’t lower.
I too have worked at shops that require those forms. One shop owner said, "If theres iron on the rack theres money to be made" Didn't take long to leave that one.
When I bring my vehicle to someone for diagnosis it is nice to know everything!:)))
Sometimes you can't win. If you quote roadworthy items to prevent "since you worked on my car.." they don't like it, but if you don't quote oil leaks and bald tyres, they get upset too
Matt. The reason the compression test lied is the water can not get out of the way fast enough. Cheers Adam
Oooohhhhh!!! that’s a good thought!!
Not blown out big enough
Yes true and is a factor. Water can't be compressed. If there was no water in the system, you should see a difference in the maximum compression reached. The difference may only be very slight, depending on the size of the blow out though.
Completely agree re. the other shops. None of the other crap matters until they've addressed the elephant in the room. Your poor customer would have thrown all that money away and then still be met with the cost of a head gasket repair. Also, for your chef friend, can recommend the HoldPeak 600amp AC/DC current clamp. It's the cheapest one I've found that works perfectly for relative compression tests.
Thanks for the video.
BTW, you're the greatest chemist/engineer/mechanic I've seen, hands down
much appreciated lol!
Should have sent a camera in the bad cylinder , and pressurize the cooling system to see what size leak it was for kicks and grins
We are both on the same soapbox. I would love to go fishing with you so we could commiserate on just how despicably pathetic society has become. If I have learned anything in my over forty years of spinning wrenches, it is there are no absolutes in this profession. You will eventually run across a vehicle that will make a liar out of you. It's just part of the gig. Great video as usual.
Thanks my friend. If you ever find yourself in Denver let me know!! Lots of fishing here!!
@@SchrodingersBox I’ll certainly do it.
Hey thank you sir I bought xtool it helped me fix a friend's misfire and transfer case encoder motor fix thank you sir 😊!! Fuel trims look 👍
great to hear!!!
You are very sharp!! I am retired …. and I have work every day in a shop diag. cars. It looked like a small leak in the wave form Big Matt! Great video!!!!
The words "Never" and "Always" are 2 of the most abused words in our vocabulary so I'm very careful in the ways I use them. Compression tests never lie. Faulty equipment and/or misuse usually lie. Engine Compression isn't always affected by head gasket issues. It all depends on what part of the head gasket is damaged. It could be damaged at one of the coolant ports and have nothing to do with Compression or cylinder head could be cracked on an area of a coolant port that is not adjacent to the combustion chamber. Most components have several different tests. Therfore just because it passes one test doesn't always mean it's a good component. The only way to pinpoint and verify is to do all the necessary tests. Hey, thankyou for sharing your vast array of knowledge with us while saving us a great deal of headaches and money as well as discovering fascination of figuring out how things work. Your intelligence, modesty, and honesty are an inspiration to me and I'm glad you do what you do. I don't believe that money makes the world go round like they say. I think it makes some people dizzy going around in circles being busy.
About the test 'lying' - seems to me that if you have a small leak, then that won't show up on the compression test but it can be big enough to let coolant into the cylinder and cause problems there. You only need a few drops of coolant every engine rotation for a big problem, but a few drops of air missing from the compression, you won't notice. Also, applying a denoising (lowpass) filter to the starter waveforms might help a lot, they're so fuzzy now you can't see much.
Hey Matt! What I’ve done in the past is install a coolant pressure tester (cold engine) and leave it (with no pressure) while I crank the engine over just like a relative compression test and if it creates pressure it pretty much guarantees a bad head gasket
Yes I have heard of that too!!
@@SchrodingersBox another thing that I have learned from Eric O. (South Main Auto) and super Mario diagnostics is to install a pulse sensor like the first look in the cooling system and sync it with the relative compression test and and ignition event. You are going to see small bumps on the cylinder/s that may have the leak instead of doing a leak down test on all the cylinders. Personally I have only seen a couple of times since I learned about the test.
Didn’t realize you were making a video about this very test 😅
Hahahaha yes I just did it. Video coming out soon!!
You can’t excuse the shop so easily! All they had to do was what MOST people do when they suspect a BHG, a chemical test. It was obvious
Compression? Or chemical.
I ask honestly cause Idk. But I haven't finished the video either 😬
Oh dear Lord... Never mind. I thought there was some kind of advanced type of chem test. This is very common stuff. My bad. I'd have just done a pressure test to begin with a kit.
Wow, 27 min in. You humored your buddy, proven that a compression test can't always be counted on over a simple code, and so far, shown the most efficient way of where the coolant is really going. Nice man.
Do I have your consent for a brain transplant?? Lol
I've finished. Thx for the video.
Knowledge is Power
I just replaced the heads because the comp was horrible turned out it was the valve stem seals. Love your channel thx. Mat.
Ima find it hard to believe 2 shops couldnt diagnose that.Could be a case of a customer concealing information.Indeed you said it yourself,now your armed with the knowledge and expertise you have become the bad guy,as you have inferred the 2 previous shops as being.
MATT, you rock brother as always by sharing ur approach and information with ur viewers and those days most of they call them professional garages are most of the time part changers I work in dealership and most of the time i see part changers not real technicians and most of the time charges the customers for things they do not need what else can i say this is the real world we living in. cheeeeeers
Thanks my friend!
Matt, Great video !!…instead of using 20 volts DC for the RC test use “AC Coupling”…change the DC to AC and select a 1 volt scale…the compression peaks will be on the bottom and not at the top as you would see with the AMP clamp setup…have you used the WPS on a radiator for a blown head gasket ??
C5 Diag
Thanks Robert - yes others pointed out the radiator pressure. great idea. I hope with the coolant it won’t damage the WPS- will it??
You can scope the radiator with a pressure transducer.
oh damn that’s a great idea. dammit I wish I had thought of that. of course this would only work if the compromise was to the cooling system but it’s better than what I did!
@@SchrodingersBox And you could Sync it with spark or Injector or flywheel trigger and see what Cylinder is pushing the Coolant without removeing a Sparkplug for Testing
Totally agree!!
I generally don't use compression for a suspected head gasket issue, for the very reasons your showing. The block test is the most accurate. If there are hydrocarbons in the coolant it has a blown head gasket. At times coolant (under pressure) is being forced into the cylinder, which would not be a loss of compression, At other times exhaust is being forced into the coolant system, which you proved with the air in the cylinder. Not sure why but this seems to not effect compression as well, or affects it to such a small degree. Anyway like your channel you do a great job. At my shop we always perform a block test on any car that has overheated b4 doing any repairs. There are times when that is simply not possible do to how severe the leak is.
Here's your explanation for it. Consider the differential geometry of the cylinder as the piston travels vs the geometry of the leak. Pistons are fast. Leaks are comparatively slow.The compression tests in all forms will always lie in this scenario. Normally a compression test is only a valid diagnostic tool when you are looking for a substantial cylinder failure like a burned valve or a broken piston/ring, etc. A blown head gasket or even a cracked head is NOT a mechanical failure in the sense that a comp test is designed for. You did the right thing. Chem test, pressure back flow test and general common sense inspection. A leak down, removing all the dynamics of engine operation from the equation is great.. Even that however does not diff between a failed gasket and a cracked head/block. Some times a wet pressure test from the cooling side and a bore scope will reveal the actual location of the leak. There are CZcams videos that actually let you watch the coolant leaking into the cylinder through the head gasket. Cool shit.
All my best to Jose here in my town of residence. And a belated welcome to you kind/smart sir. Now come back in mid/late August and tell us how well you like it here.🤣 We know.🤒
I think you are correct in your assessment of why the test failed.
Matt, the compression test doesn’t lie…it simply isn’t useful for conclusively diagnosing a bad head gasket. It is a basic test to identify the mechanical condition of an ICE to generate sufficient compression for combustion, nothing more. Coolant leaking into a cylinder (or combustion gases out) can be a trivial amount of loss of air compressed relative to that of the displacement of the engine cylinder…for a 2 liter,4 cylinder engine, 500cc of displacement compressed (on EVERY stroke) relative to what may be a pinhole sized leak in the head gasket. Science. A blow-by (leakdown) test or the chemical test of the coolant, both of which you show, are far better tests for detecting a failed head gasket than using a compression gauge, and are just as fast (or faster). That is the explanation…science.
Last, since you are an educated man, a diagnostic test is incapable of lying. The results provided may be misleading or inconclusive, but lying is the intent to deceive (knowing information is false). Lying requires more than just data or information. Data doesn’t lie…people do.
Agreed. I should say it is misleading but you are right- it is reporting the conpression accurately
No, he has 6 children, he can't afford better equipment. That's the general reality of our modern world.
Good work! FYI do the chemical test outside, It will pickup hydrocarbons in a garage & give you a false reading, it’s happened to me
Excellent! Thank you Mat! Super Mario has an interesting video named "Don't trust relative compression test".
I will have to watch that!!!
Great video matt as usual, cheers from ontario ca.
Bernie Thompson has a pressure transducer that he uses a scope to measure the pressure pulses in the coolant, then syncs to #1. That may be way more sophisticated than you want to do, because most do-it-yourselfers can't do it.
Small leak, large displacement = little compression loss.
I don't understand why when you give it throttle you get more white smoke....more throttle = less vacuum sucking coolant in..... unless it's when you let off the throttle after pressurizing the coolant with more throttle.
Matt, it is very common for a cylinder that has coolant ingress not to show low compression if the leak hasn't gone in long enough to cause cylinder damage.
Also, any coolant that gets into the cylinder may actually help to seal up a small leak.
Any liquid in the cylinder potentially could even reduce the cylinder volume enough to balnce any existing compression loss due to any damage that may be present, or present a partial hydo lock effect, essentially increasing amperage seen on an RCT and show up as a balance with other cylinders...mind you I'm just speculating and thinking outside the boxwrench here..lol😁
The leak may be small enough to allow combustion gasses into the cooling system, but since each compression stroke happens so quickly there's very little time for it to be visible on any kind of compression test.
With the leakdown test, you are doing it with the piston in a static position, over a much longer time period comparatively.
One way that may work to pinpoint a compression leak into the cooling system, and at the same time identify the problem cylinder, is to put a pressure transducer on the radiator neck or coolant header tank, and also connect a 2nd channel to one of the cylinders as a sync, ie. an ignition coil etc.
You should be able to see the pressure pulses at the cooling system and identify the problem cylinder by using the firing order and cylinder sync.
I'm pretty sure you already know this, or since you're a bit of a thinker you will most likley think of it anyway, perhaps it just simply slipped your mind in this video🤣🤣👍🇦🇺
Correct on everything. We are going to test these concepts in next video.
Also, Matt, we appreciate your honesty and skill. The society has propped up theieves and conmen in media and music. We need more men of honor to thwart this trend. Be well Matt
Thank you!!
Back around 2000, I was a victim of failed head gasket diagnosis I think. I had bought my daughter a 92 Pontiac Sunbird. It had overheating problems and the local chevy dealer kept replacing stuff such as fan switch and radiator without diagnosing the real problem. She was away at school and it ran hot while she was somewhere she didn't want to stop and really overheated it. I drove there 6 hours away and the car failed to start. So, thinking it probably needed an engine and possibly a transmission, I called a local salvage yard and sold it to them for $250. On the way back to her apartment I stopped at a Ford Dealer and bought her a 99 Ford Contour with 23k miles on it. It lasted her to 170k miles with questionable maintenance. That chevy dealer has terrible mechanics based on that experience and others, just parts changers.
Hi Matt, full radiator, cap off crank engine and look for the bubbles, no tools needed..
the water pump itself often causes bubbles though. I have tried that many times and it’s inconsistent.
also- even if it was a cylinder leak- how would I know WHICH cylinder it is?
@@SchrodingersBox Hi Matt, fair comment, but there's a difference between the more consistent small bubbles of a water pump leak and the surge of an compression leak whether it is from a porous cylinder, cracked head or blown head gasket.The point I was making is that you can use this to get a fair idea of the problem on the side of the road away from home or service centre. As for which cylinder it is you could try leaving the spark plug out of each cylinder in turn and see if there's a reduction in pressure in one or more (adjacent) cylinders.
Well wait-- if you have to remove the spark plug to do that, why not just do a leakdown test to bring with? Also what if the cylinders are under the intake manifold? And also what if the compression loss isn’t to the cooling system- how would that be determined- you wouldn’t know with this test.
A method is needed where you can identify all cylinder leaks and identify the affected cylinder without removing spark plugs.
Electronics will never in a case like this beat leak down test
"SAY HELLOO TO DA BAD GUY '' lol .. Sounds like a new Schrodinger's Box merch hat ,shirt, or sticker .
can’t live without at least a hat!!
the coolant in the cylinder is displacing air thereby raising the compression
Agreed. That makes the most sense. The coolant can’t leave as fast as it entered so compression isn’t changed.
Hey, Matt. Gil here, after a long time since I last posted anything (always good, never bad or hostile). I did not zoom in on the spark plug view at 38:24 to see if the electrodes on the darker insulator plug were more than the #7 plug, but if there is any more electrode wear on the #7 it might have been nominal at most. Anyway, the reason #7 could have been more white/clean looking is because having coolant (or water) in the combustion chamber, especially if ignition occurs even intermittently despite the coolant being present and hampering the ignition process, the spark will be getting steam cleaned in essence, and any byproducts of combustion that would normally be on the white ceramic insulator will be getting blasted off. I used to look at spark plugs and read them whenever I pulled them, even for a low mileage, otherwise good running engine, just to make sure there was nothing unusual going on with an engine. Any time I have one insulator far cleaner and brighter than the others told me we likely had coolant getting into the combustion chamber, and the customer would be coming in to get the misfire corrected with a self-assessed need for a tune up. Nope, no tune-up would be done. I would dig a bit more, using a compression test and/or BlockCheck. If they had a blown head gasket my replacing the spark plugs we not going to help. I would usually leave it to the Service Writer (Ford dealership in SoCal in the 70s and 80s) to break the bad news to the customer. Once the head gasket was repaired I would often get the car for a final scope and set, and if they really needed spark plugs I would install a set. Often someone else would have already installed new plugs in an effort to "fix" the misfiring caused by the blown head gasket. Gawd, the stories I could tell you...
Anyway, good call on the head gasket, and Thumbs Up on not hammering the customer with even more asked of their financial resources. And, yeah, I would do the same once in a while for folks who came into our shop after trying to get a problem fixed by other places. My heart would go out to them as it means food off their family's table. The bad work was not my doing, but I was doing plenty well enough without having to be the one to bring more heat on them. The goodwill I got was tremendous, and I always felt good about being able to show that not everyone in the auto repair business is after their last nickel. Fair is fair, right is right - and I have neve rbeen hurt by trying to the right thing even with issues I did not cause.
Hey Gil good to see you back!!! Thanks for the great comment and hopefully we see you more consistently like we used to!
@@SchrodingersBox heh heh, it is easy for me to get side-tracked. Retired, several vintage pony cars I n4eed to tinker on or work on during car Season, and lately I have been working on a special project that I think will be of interest yo you. Until I get certain paperwork filed and more testing done, I need to not get into it in a public forum. But, frankly, I thing this is going to end up being aa nicely disruptive game changer in several industries - to include auto diagnostics and repair. When I am able to provide more detail you are my very short list of folks I want to see what I have been up to. Early warning, put on your seat belt, you are going to need it... heh heh... It's all good...
IMHO,
It may be possible the other shop pointed out the other issues to give the customer an ability to make an informed decision on the investment needed into the vehicle.
I would imagine if they didn't know all of this information, they would have asked you to do the head gaskets rather than cut their losses.
Excellent video!
Your line of thinking is fantastic and i completely agree with the "Bad Guy" outlook.
The investment outlook is for people who wish to succeed. Absolutely solid advise!
Your a good man Matt!
Thanks for sharing. My guess is that the hydrostatic pressure of the coolant is giving you good compression.
Great information, just a guess this has an iron block with aluminum heads and uses a multi layer steel shim type of head gasket. They do this to allow for some movement between different expansion rates of the two types of metal. Gasket may not be blown just leaking, I've had the same symptoms and replaced the gaskets not being able to actually find the spot where it had failed. I always wondered if it would help to just re-torque the head bolts.
Car overheats I’m doing a oil changes right away. Good to see you against sir. I did in fact buy the d7 on your recommendation and I’m super happy with it so far. I’m a heavy truck guy and have my fair share of pick ups to work on. This tool makes a lot of diag possible. D7 for the money is the best.
Great to hear!!!
Matt, love this video. Thanks
Glad you enjoyed it!!
Just because it's a shop doesn't mean they're professionals! What's sad is the fact that they wanted to spend $4000 which would be a complete loss to the customer because the major problem wasn't fixed. The shop just wanted to do easy stuff!
I absolutely agree.
I am a mobile mechanic but I also make and sell jewelry on the side. Also work a part time job. Definitely trying to funnel more money out of my mobile mechanic business though
I imagine the mobile mechanic business will have more potential but one thing I can tell you- ALL financially successful people I know always have multiple sources of income. Whether that’s working multiple jobs, investments, having a side business- whatever. So regardless of where you focus I’d say you are on a better track than most!!
Great job Matt, Thanks! Another way the RC test can "Lie" is with a valve issue, that's why It is better to do an RC test with a pulse sensor in the intake. I don't think it would help you in this case unless you put one in the radiator neck as well.
Agreed! Will do that next time for sure.
Unfortunately dishonesty in the car repair business has become so widespread that many people simply accept this type of scenario as part of car ownership and simply sell the car as soon as it starts to develop problems. An expensive solution, but the approach of many who cannot or are unwilling to learn more about car repair!
Saw a 92 accord, no brakes unless you pump, obviously been filled, no visible leaks. Customer says a cylinder issue. I have had a 93 Sanoma...self bleeding:)
Pico makes a pulse sensor you can hook up to the radiator and scope. This would be a viable alternative to the misleading reading of the compression test.
I never use a compression gauge, i rather use a pressure transducer and a pulse sensor. more precises. great diag and great find.
What do you do if the compression is not lost to cooling system though?
@@SchrodingersBox like a head gasket issue with a oil coolant passage. i put a pulse sensor in the crank case like where you fill up the oil and use a sync to figure out the cylinder. run the cylinder sync to a CKP or RC. Had one that had misfire in two cylinder and it was a blown head gasket that was 2 and 3 were compromised saw it in a rc test. leak down test or put smoke in cylinder 2 and saw smoke comer out on cylinder 3.
Makes sense!!
Short answer: chemical test for presence of combustion gases in coolant. If there are gases detected, engine is faulty. Additional diagnosis is required to determine which cylinder(s) have a problem, and the cause is not limited to a head gasket.
Yes but I have a video that also shows a false negative test on the chemical test. I agree I have never seen a false positive but I have seen false negatives several times.
@@SchrodingersBox note that head gaskets can leak from the combustion chamber to the coolant side or the reverse (coolant side to the combustion side). So, yes, not conclusive by itself. But, in this case, you also had coolant in the combustion chamber (as seen in the exhaust). That is conclusive.
Thanks for your time.
Any time!
look inside the #7 cylinder and you will see coolant. the coolant is raising the compression.
That explains it!!
Hi Matt, good to see you again!!
Yay! My friend is back!!! Always good to see you!!!
Super Mario diagnostics did a great video showing how the relative compression isn’t the end all be all solution to mechanical health.
Food for thought. When metal is cold, it contracts, when it's hot it expands. A cracked head makes more sense with all your tests than a head gasket does. I haven't finished the video yet, but my mind is screaming cracked head.
Yes but temperature made no difference. I believe it’s because coolant pools in the cylinder and can’t be pushed out as fast as it drew in so compression is the same.
I left the industry in the late 90's due to 2 different dealer shops regularly asking me to rip people off and 'find something we can sell', I just wouldn't do it. I wonder how many good people just leave and move on. I have also experienced, asking for service as a customer and having shops simply reset the light and clear the codes up to having brake lines cut to sell brakes, unreal. These guys today are just so lazy.
I hear you man. I don't work in the industry but I am fully aware of many of the practices- I see it all the time. Thats why I like doing my own thing.
Welcome back homie
Wah da tah my damie!!!
The chemical test is awesome. I have to procure that tool or kit for head gasket diagnostics.
One of my favorites!’
Matt sir, if I may ask, do you have a particular company that you prefer to use dye to determine if carbon dioxide is in the coolant.
Was the "clean" looking plug from #7 (the cylinder with reported misfire)? If so, might have been steam-cleaning due to the head gasket failure into the coolant passages.... Might have been interesting to see what the top of the piston looked like, as well. Great video, thanks!
Yes but it also was could be clean looking because it only was replaced 3 weeks before while the others were in there 5 years.
No car company has provided more interwebs mechanic fodder than AMC/Jeep/Eagle/Diamler Chrysler-Benz/Fiat. Those 100 dpi images from the shop quote are 😂
God bless you ND jose
Most of the time a blown won't show relative compression being different because it was most likely a coolant leak into the cylinders
I am learning horseback riding, and various other farm skills to add to my mechanical engineering background. So incidentally, I happen to be building a second skill set as we speak.
Hey that works!!! They always need ranch hands in the rural area of Colorado!
Hi Matt, I agree with the other guys on using a pressure transducer on the radiator and sinking another channel to cylinder 1 to trace down the contributing cylinder following the firing order.
Then verifying pressure loss at that specific cylinder via leak down test.
100% agreed!!
A friend of mine was paid temporarily via a prepaid card and someone from company had access and spent $990 of it and he could not do anything. I agree, California hates hardworking middle class.
Strange how they did not did the chemical test when there is white smoke. I know it requires some money as you lose the fluid that you have put in the test tube, but disassemble sparks required time and you can damage something.
The chemical test is such an easy test to do. Everyone can do it and you can do it when you want to buy a used car too.
i know it's a bit expensive as a tool, but using a gas analyser, is the easiest way,more accurate, and much faster than the other tests. less than 10 seconds. you stick it in the cooling cap,and done.that we was doing in the previous workshop i was working. and even if you don't own, i am sure its going to be something near by.i will suggest you Matt,to give a try to this technique, and share your thoughts.
You should buy the vehicle Matt. It would be a great video!!!!!🎉
Golly I am tempted to get free the customer $200 to bring it back and let me experiment it for a weekend.
The fanciest tool I have is just a fancy code reader that can test battery and alternators and a few other things,
I do have the fluid tester and a test light and a digital multimeter, compression gauge, fuel pressure gauge, vacuum gauge, voltage gauges….. the old school basics. That’s it.
Been fixing my own cars 40 yrs ans now my kids. Rarely someone else’s just cuz it’s a hobby for me and my kids keep me busy enough although at one time it was a thought.
I think it would help some to have better tools but even as a medic I found people depending too much on fancy tools and forgetting the basics.
Our brains are the best computers in the world as we see, hear and feel more than we know but less when we depend on other things.
Those other mechanics have to just be thieves cuz head gasket is the first thought after over heat ESPECIALLY if the car has the positive pressure cooling system without a true overflow as the pressure has to go somewhere and head gaskets are the weakest place.
Thank you for your knowledge and videos.
I watched simply cuz your video randomly popped up on yt and I know you always have good info.
It’s too bad she go treated so bad as a head gaskets are relatively cheap to fix unless things are warped.
Welcome back, Schrodingers Box
Enjoy your weekend Schrodingers Box
👍
SHARP Schrodingers Box
From Nick Ayivor from London England UK 🇬🇧 ⏰️ 15:51
That sounds like a no quote. It's like they didn't even really want to fix it
Usually when shops pile on services like that, they are trying to scare off the customer, as they don't want to work on it. If it's a dealership, this is where the car salesmen comes in.
Ohhhhhhhhhhhhh!!!!!! Man that’s a really good point!!!!! Never thought of that!!!!
Yeah, I have seen that action also. For some cars it is best for the customer to get another car (Pintos for instance), but no need to do it like that...
@@SchrodingersBox
For those about to rock….AC/DC Amp Clamp!!!
should have been able to put pressure on cooling system and find water entering cylinder still lots of work would have to remove all spark plugs. i ran into it on my wifes truck 360 dodge would skip every morning for a few seconds had good compression. pulled all plugs and checked one had water in it
Thanks Howard. absolutely would be a valid technique.
YOU WOULD THINK THE VOLTAGE WOULD GO UP ON THE LOW COMPRESSION CYLINDER .
Fantastic observation!!! You are absolutely right. It does. I simply inverted it so it would match the amperage pattern for comparison.
Brilliant dude! You definitely understand it!
@@SchrodingersBox THANK YOU BROTHER , I BEEN A TECH FOR OVER 30 YEARS, THAT VOLTAGE INCREASE PROOF THE LOW COMPRESSION ON THAT CYLINDER , IN THE FUTURE MATT DON'T INVERT IT. LET THE CURRENT DROP AND THE VOLTAGE TO INCREASE . IT'S MAKES A BETTER WAVEFORM EASIER TO READ AND MORE DRAMATIC LOL.
Acknowledged. In fact I did point it out in the video that I inverted it, but I lost it in the editing.
Really impressed with you!! That was awesome observation.
@@SchrodingersBox THANK YOU !
....it's whatever the DA says it is (regarding the upper limit) because there's no accountability. Look at L.A.? It's gnarly
Matt use the search option next time. It's located I. The top right corner. It's great at detecting keywords. Thanks for the recommendation on the xtool. It's great
Thanks I own the stool and it’s a little cumbersome at finding the needed pids. I squally just use a generic scan tool and go to the stool only if needed. Thanks
hey Doctor Matt, it is more accurate when you test the compression together with the intake pulse.
A little classic rock humor. I love it! AC⚡️DC 11:37
Just take the rad cap off and crank. No set up needed. Will dx leak into coolant system at least using engine compression already supplied. Obviously not into intake/exhaust/or block. But quick and most common.
Had a95 land cruiser with straight engine, I think 4.7. Milage??? Runs nice! Wanted tires but dead battery no start etc.. checked and charged good bat. Slowly cranked key like 10xs and start. In the middle of changing tires, it started , but with a couple high power fans hard to hear. Ran for 20min or so, long story short, unhooked neg batt. Terminal and cranked the key to start to shutt off vehicle to finish. I'm guessing starter but all this happened after fussy customer showed up. So I don't know if they were mad and remote started or problem with what's on car. I think a car problem. Anyways, I will probably never see that car again:(
As far as Hose building a business. It is possible, but when you start doing more you start paying more. He has got to pay taxes on it before he gets caught, because he want to accept debit cards, and everyone wants to pay that way, and he will get 1099's from his credit card proccessor. If he claims it as income then he has to get a vendors license and start collecting sales tax (a time consuming process in Ohio), before they catch him. Now he has got to do accounting to keep track of all his expenses and billing (more time). Now when he does his income taxes he is going to have probably pay an accountant to do them, I don't but most people will. Then he has to get garage keepers insurance, so if he has an accident driving a customers car he is covered. Then he will have to get general liability insurance if he does mobile work at other businesses. Plus he will want an umbrella policy to cover all those policies. It goes on and on and on....
Totally agree. All the MORE reason he deserves his success and reward and all the more reason people who don’t do all of that are not victims of “misfortune”
@@SchrodingersBox Yeah, a lot of people don't realize the expense and effort you put into you success. In Ohio, it still a crime to steal though, so at least there is that.
Agreed 100%. It also in my opinion explains the dichotomy between the business owner and the unskilled labor. Who deserves to make the bigger share of the profits? Is it the person who built a business out of their garage working 14 hours a day without not even a day off for 5 years, took out a mortgage loan and a business loan in addition to securing capital from private investors, made arrangements with distributers and manufacturers, got insurance, hired employees, hired legal resources, analyzed the market to position for growth, learn antitrust laws, validate zoning restrictions and reinvest for expansion….
Or is it the guy who puts the products on the shelves?
Leak down seems to be The Test.
It is by far the most reliable and most informative for sure. However it also the most laborious.
Matt, not sure whether you'll see this since this video was put up about a month ago. Regarding failure of the fluid test for blown head gasket, Eric O. just did a video where he talked about needing to rev the engine pretty high while doing that test to blow out accumulated air before exhaust gases can make it to the fluid. In his video the fluid stayed blue for a long time until he revved the engine several times, eventually turning the fluid yellow. Thought you might like to know this for future reference.
I see it and yes I agree it’s a good advice.
Minor gasket failure, not surprised that the compression didn't show a definitive failure. The gas sampling is scientific, positive. The compressed air test scientific, positive. Plus the other many possible ways it find a head gasket failure. The compression test fantastic for mechanical issues, valves, lifters, rings, cam... Don't loose sight of the fact that you did use proper science. Labs are full of special equipment every analytical method is as good as the information it can identify. Step back breath, great job.