The Hidden POWER ROBBING Secrets of a 115hp Johnson Motor uncovered!!!! Engine down on power.
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- čas přidán 19. 03. 2022
- The Marine Doctor takes you through steps to uncovering the hidden secrets of a 115hp Johnson Motor. These steps can be applied to all brands. #johnsonoutboards #mercury #evinrude #tohatsu #outboards
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way cool video... i have the same problem... low compression on 1 cylinder... now i know what i need to check and do ... like the video and subscribed 👍👍👍
Wish I could find a marine mechanic in my area as good and honest as you.
Thank you very much for that.
Please use a lapel microphone. Interesting, but Hard to watch
You using a potato as a microphone? I had no issues understanding him. Might need to upgrade from that old ass Nokia and walkman headphones
I saw that broken wire at 2:04
I would have stopped right there and repaired it and ran it.
PRO TIP These engines have bad fuel lines underneath and behind the carbs. They have the little plastic nipples that break. they are crank scavenging fuel return lines and they piss out lots of fuel into the engine when the bad plastic lines break. take the carbs off and replace lines if you leak gas inside the cover. This will throw off fuel mix. you will have no start condition when engine is hot but has been off it vapes in gasoline and will flood the engine. This fixed mine, it is running like brand new. tiny blip of the starter and it runs and accelerates and idles perfect.
Another plastic fuel part that goes bad is the manifold splitter that takes one line and sends gas in two lines to each carburetor
These form micro cracks which let in air and will leak gas too. Make one yourself with small copper fittings. It also will never go bad.
The plastic fuel parts go bad and ebay parts are garbage plastic too. Go with replacing what i just said with the 115, 140s of around 1980s years. They will be more reliable if you do these specific repairs defiantly.
Its not the spark plugs, ignition, or timing. Unless you run it with no oil, the only thing that Always goes wrong with these things is bad gas and bad plastic lines with the gas related parts. Assume all fuel related plastic lines pumps splitters is junk if its old. Honestly these should all run a pumper carburetor like jet skis with 1 inlet and no other lines whatsoever. 1 carb, too makes life much easier. e/j i got a probelm waiting for you too.
Thank you for this.
Is there any risk of damaging impeller when you dry crank it for compression tests?
No
I have the same motor. It's a 1985. My idle has been sporadic. Today I did a pressure check. Top and Bottom left was 110 each. Top and Bottom right was 122 each. What are your thoughts?
Also I don't see your fuel filter. Mine is secured in a clamp held by one of the Cylinder Head bolts. Lower left side.
Pull off the head and take a look inside. You are welcome to send me pics if you like.
I wouldn’t waste my time pulling the head off. Look up adjusting the carburetor
@@cumminsbayou Fixed jets...
@@TheMarineDoctor adjustable linkages that have a huge part in the way they idle..
@@cumminsbayou then u woulda missed the mechanical damage. not coming t you to fix anything friend.
Whats the big difference between the 100hp and 115 hp? Just the displacement or they put something on it to get 15 more horsies out of it? I got an old 79’ 100hp and have had a newer 115 hp apart and i couldnt find a difference.. same size looked like with same parts..
Older ones had the HP rated at the crankshaft, not the HP at the prop.
Late 1970's to early 1980's 140HP I believe were actually the newer 110/115hp crossflows except for maybe a few models which might have actually been 140 HP at the prop.
ignorre the response below.
All cross flow engines from around 1974 to the end were all 3.5 inch pistons from 85 hp v-4 's to the v-6 and even 300 hp v-8's. The differences were porting and exhaust flow . there are tuning ports in the exhaust. The 135 and 140's had a hump on the exhaust that aided in more h.p.
it is true they changed rating from powerhead base to prop but that is not the answer to your question. there is a bit more in jetting but main differences were in porting etc.
oh yea... what kind of gauge did u use to check the compression ???
Analogue
I'm getting 110lbs compression each cylinder for that engine, is that close to specs?
Variations of gauges can impact compression values. All being the same is a good sign. I typically see around 130 psi on strong engines or new rebuilds. Mind you...it never hurts to pull the heads and get a look at the cyl walls. The 20psi has gone somewhere...possibly slipping past the rings due to wear or piston slap.
@@TheMarineDoctor There was a change in the 80's to a thicker head gasket to try and deal with ethanol by lowering compression to around 110. At the time the service bulletins stated for 3.5 bore anything over 100 was good as long as within 12 percent. the big dog engines were 90 or better. It 1helped engines from blowing over crappy fuel but did rob a bit of power.
that little chip might not mean as much as you think if the rings are fine. the big question is how is the cylinder wall? if you cant feel any scoring, id run the motor and see how it idles. i dont see many healthy crossflows putting out much over 120-125psi. this ones been bored .020, which means it was most likely decked as well, which would explain the higher 130psi on # 3. again, i always run the motor as all issues will show up at idle.
@Enticerll ah yes if its scored then by all means. couldn't see the exhaust side in the shadow! technically 15 psi is right on the edge but good call popping the head. thanks for the video!
well, your answer gurantees i am never bringing you anything to repair. wow!
@@daddski1 what? why? gotta love comments where you don't speak like an adult and use words to describe your disappointment.
doin great man, cannot believe some of the armchair mechanics in the comments and their claims... OMG... what has happened to integrity and correct thinking? Seems like laziness and a buck is all they think about and not actually getting to the root of the problem, just fix the symptom.... Been a marine mechanic since the 1960's. Still getting paid even after retiring because i DO compression tests etc lol.... I find out WHY the engine messed up, not just hey! I see a bad wire lmao.... anywya, best to you, it seels like you are doing well so keep it up.!
My rebuild still going strong after 3 seasons. See so many that fail prematurely.
I just had to repair another shops rebuild. They had used silicone between the crank halves.
@@TheMarineDoctor wow, i've discovered shoddy work by other fly by night mechanics but that's the worse.
@@TheMarineDoctor Facepalm. I take it they never bothered to look at the service manual to get the correct stuff, the anaerobic gasket gel. The name I can't think off the top of my head.
@@havocsquad1 permatex. Yep
@@havocsquad1 it's called gel seal. permatex makes it now but make sure its the right permatex and not the black. it is reddish/translucent color.
Use K G K plugs. Huge difference
N G K
This is a load of crap a compression check is the biggest waste of time and has caused more psychological stress and parted out outboards than anything else. I’ve ran many omc outboards and some had 60 pounds of compression. I no longer even own a compression tester for piece of mind
There is some truth in this. I have a 6hp that shows 62.5 and 67.5, and it runs and idles just fine.
@@Steve-wz5pz some of the research I’ve found say the commercial models had around 60 pounds of compression from the factory. I’ve just never gained anything from doing a compression check and that’s after many outboards
Only thing ive gained from a compression check was a few extra thousand when i sold the motor. But it just tells you how far gone the cylinder walls are and how bad the rings are..
They will still start and run with low compression, but not as good as they should and certainly won’t have the power it once had..it’s much more important for all the cylinders to be within 10% psi of each other..that being said, the one different looking spark plug tells you immediately there’s no spark on that cylinder
dude.... just stop, get some help lol.... Compression testing can help diagnose an engine quickly. The fact hat you stated you would keep running this engine after him showing piston damage at the exhaust side of the piston AND scoring in the cylinder is just an example of poor mechanical skills and laziness. Stop misleading people friend. run our stuff however you want but dang, don't listen to armchair mechanics, lawyers or doctors. in this persons thinking blood pressure doesn't matter either apparently lol.....as long as the heart beats you are good to goooooo lol..... just toss that blood psi cuff heheheee.