BMW E92 335i What Caused N54 Cyl 4 LOW Compression: Borescope
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- čas přidán 1. 09. 2020
- BMW E92 335i What Caused N54 Cyl 4 LOW Compression: Borescope
Its been a bit crazy here the last 7 days, however today i got a chance to use an inspection camera to have a look in to cylinder 4 to see what might be causing it to be down on compression.
If you missed the previous video. Cylinder 4 is down 30% on compression compared with the other 5 cylinders.
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Probably worth doing the injector seal and de-coupler on that cylinder, going to be the cheapest option to try. maybe pull an injector from the other motor you bought and put that in just to rule out the injector as well?
My best guess is 1) ringland failure. Symptoms would be low compression, misfire with no codes and excessive blowby out of the oil cap, smoke coming out of the exhaust due to the broken rings and excess oil getting into the cylinder. 2) Broken valve spring, yes it is very uncommon in the N54 but it does happen. Symptoms would be low compression, misfire with no codes and a valve tick that doesn't go away.
For now just swap the other N54 engine you have and do an N54 engine rebuild series on this one.
Good luck, keep those videos coming!!!
Aight aight I’ve been waiting for this!
Like others are saying swap injectors around and install new seals and decoupling rings when you do. Look for evidence of blow by on the injector stem above the seal when you remove #4 injector.
Firing order is 1-5-3-6-2-4. So maybe swap injector 3 and 4. They are 360° out of phase (crankshaft rotation). Remember to re-code the injector calibration in INPA after injectors are swapped.
I am leaning towards cracked ring land, but try the easy and cheap stuff first. Maybe redo the compression test on the cylinder dry and then again wet. If it is ring related, compression should increase with some fresh oil in the cylinder I think. You want to do them back-to-back to minimize the effect of other variables changing. Back off the throttle body to intake manifold bolts to relieve the vacuum in the manifold.
I pray that you get through this 👏🏽
See how high the piston goes up and compare to other cylinders.
I suggest a cylinder leak down test! It's the next step after finding compression is out of spec. The procedure will help troubleshoot where air is escaping and how much, using an air compressor when piston is at TDC. Things you couldn't see clearly through the boroscope such as valves and head gasket. Just a suggestion. Good luck on your N54! I just recently bought a 335i and love your videos :)
So have a friends car in my garage and it had a weird issue, wasn't at all down on power (or at least didn't seem to be) specs are GTX3576 single turbo, E30 mix, JB4, MHD BMS back end flash, watermeth kit, 6MT, 7" IC etc. Nothing super crazy, just a basic responsive single turbo setup.
So after a few races one day it developed an issue where it would blow some smoke, tips of the exhaust were oily. Suspected damaged turbo to begin with, so turbo was sent away for testing and came back fine. no dramas with the turbo what so ever. No visible signs of damage on the turbo either.
So I investigated it a bit more and couldn't find any real faults. Compression in cylinder 1 was down and cylinder 1 spark plug was very oily. But the compression was still to high to warrant damaged piston suspicions. (compression was 150psi cyl 1, 180psi 2-6)
Got the engine stripped down today and found a very unusual break that I thought I might share with you guys. The car has 80k km on the clock and is a 1 owner AFAIK, always serviced at 5000km, good fuel used, quality parts always fitted.
First thing I noticed was the wet oil in cylinder 1, the head was coated, the piston was very oily, and once wiped off there was no noticeable damage to the piston top, or the cylinder head, I did notice there was a lot of severe detenation on top of piston number 5 and also evident in the head of that chamber. I can only assume it has a faulty injector and that has caused the detenation in that cylinder alone. as all other cylinders are near on perfect.
Cylinder 5 Det marks:

Cylinder 1 Oily

Cylinder 1 piston top, oily but no damage:

Damage on cylinder 1 bore:

Piston number 5, clear signs of severe det:

First sign of damage on cylinder 1 I noticed was when the engine was pulled to TDC the piston didn't come all the way up, which I thought was odd but isn't unheard of on some engines. But when inspected cylinder 5 I noticed it came the whole way up, so I knew something was astray.
Piston number 6 all the way up:

Pulled cyl 1 back up to it's resting point and also noticed it was sitting unlevel, it was approx 20thou down on the back side of the piston, but at least 80thou down on the front side. this is the way the gudgeon pin runs, so I was concerned from this point that either the pin had collapsed or the rod had bent.
Piston number 1, clearly not at TDC and not running straight:

On to disassembling the bottom end, and all bearings, mains and big ends were perfect, you would expect this engine to have traveled no more than 10,000km it has been kept that clean inside. the bearings look near on new. Infact all the bores (apart from cyl1) looked very healthy also.
Removed the piston and rod combo from cylinder 1 and found a whole heap of mess. The conrod has bent into an S shape and tilted the head a little, causing the piston to run on a funny angle, pushing the piston skirt into the wall of the cylinder and obviously jamming the oil ring tight on one side and more than likely not touching the other side, hence the excessive oil movement from that cylinder but not to much compression loss.
This doesn't look super straight:

Piston skirts being mashed up against bore:

Other side:

Rod 1 vs Rod 2:

This is a very odd failure on such a mild setup (considering how far other people have pushed the N54, myself included)
bmw.spoolstreet.com/threads/n54-failure-335i.311/
It would be good to see the full length of the bore at BDC. The inspection only showed a very small sample of the piston wall. Also after cleaning the mirror attachment inspecting the valves would be a good idea (barely saw one and there are 4 to look at) for cracks or seat damage.Check the top perimeter of the cyl. head gasket for any brown staining that would show coolant burning (IE a blown head gasket). If all looks good I would still try to re-torque the head (with all the boost you are running)and recheck the compression including a leak down test. Remember to do all the basics of the testing like adding a few drops of oil to the cyl. to see if there's a bump in compression with that as well.Good luck and hope all goes well.
Obviously burning oil in that cylinder, either cracked valve seat or bent valve, I’d take inlet off m have a look 👍🏻 cool video as always
Old injector seals can go out at this kind of boost. And check by scope if all the pistons reach the normal TDC. So you know you don't have bent rods. Good luck, Dutch regards Nico.
Good job on using the Borescope, your bottom end doesn’t look like there is an issue. What I noticed is you have not done a leak down test and that is a step you do Always right after a compression test if you have lower compression then normal. Before you tear that engine apart I would preform the test so you can check if there is an issue with a leaking head gasket or a valve issue.
Good luck!!!
First thought was is the rod slightly bent, worth checking piston height. But a lot of people saying injectors / seals and you've got a donor engine. The optimist in me would swap it over fingers, toes and everything else crossed, just in case it is. Good luck!!!
Not the worst I’ve seen but will be interesting to find out.
I’d take a closer look at the valves and valve seat but would also compare cylinder to cylinder with the scope so you have a picture of what you’re looking for.
Hope the leakdown test gives a definitive idea of what the problem is, I couldn't see anything out of the ordinary on the boroscope
Doesn't look to bad! Leakdown test might be more telling. Another thing you can do is monitor knock and ignition timing variances with your software.
like someone else said the injector seals maybe, could be corroded if not running the full stock engine covers brace thing and cabin filter
Would have been interesting to see down into the other cylinders as a means of Comparison. Hope the engines okay though 🤞🏻
Is it possible that a leaking valve cover gasket / cracked valve cover resulted in the plug looking dark like that? I don't recall which cylinder, was 3 or 4 on mine, that had oil stained plugs when I changed the cover
Stock piston ring gap is never usually big enough for that much heat expansion created with that power, and people blow alot of motors not knowing this. In other words, the rings might have expanded too much. Hope it its not that, but good luck!
Nice work, keep it up.
No worries about not having a conclusion, I for one would rather be able to watch along and see how it all develops, rather than you just releaseing a video in 3 weeks and say "oh it was just xyz" and me have to wait until then to see more content.
Cheers dude. I didn’t want people think I’m click baiting them. But I guess this shows the reality of what people go through trying to work out problems.
Going with my same advise from last video. Spark plug looks rich, not lean and not like burning oil, if it were burning oil the plug would be glossy sud on the plug with purple ish tint. Look at the intake valve for that cylinder. The piston has carbon from a rich condition. Do a leak down test.
Would be interesting to see another cylinder to compare, to see if it's just as oily. That amount of oil makes me think oil is getting past the piston ring which is why it's losing compression, but I'm no expert.
The top of the piston looked like you were burning a significant amount of oil. Just a guess it looks like the rings are toast. Good luck mate great content
Thanks man, a few people have linked to threads on broken ring lands, this is looking very similar.
I suggest you check the fuel injector seal at the tip of the fuel injector. Compression can leak past that seal. But yeah do a leak down test first
Have you checked the injector? A shot injector can give all sorts of weird problems on the N54 (my engine sounded like rod knock). And if the injector is loose in the cylinder head that might explain the loss of compression.
I haven't pulled them out or anything. If i do a leak down test it should show that tho.
Add atf on those pos motor are notorious for the rings to stick
is the carbon on the piston anything out of the ordinary ?.. other pics I have seen,looks about the same....
Maybe still a hairline crack on the ring land or even loss of the plating on the top ring face, or even hot rings causing them to butt slightly and wear quickly, look for shiny spots on the gap faces. I think you might have caught it early and a hone and a set of forged pistons might be the go...... 🤔 Above the ring reversal point is probably oil residue. Bores still look excellent.
A leak down test would help and a good set of ears will tell you if it's intake, exhaust valve or ring pack.
Valves might need a freshen up, get them seating good again
Stuck injector?
"a container of stock" - what do you guys do for your main income?
I've always wondered - because you're dedicating tonnes of time to this series! Love it
Currently we import what we refer to as black gold..... We've been in business for over 10 years, and since we moved out of the rented premises it has given myself in particular some more time to work on youtube.
Zero To 60 i assume its car related but the only thing black gold that comes to mind is truffles 😅
Glad to hear you’ve had more time to work on CZcams! We’re all enjoying it!
Mine is currently limited to weekends which definitely puts a dampening on it haha
Have you used inpa to monitor what the knock sensors are reporting? Is cylinder 4 standing out there? If it was a ringland or bent rod it would be knocking minorly
That is a good point, no i haven't. Will look in to that as well. Thanks for the suggestion.
Very likely the ring land but you cannot see from the top, top part is not usually cracked.
(turbos off, head off, sump off, pistons up and out)
Leak down test will tell you If it's head, piston or head gasket
@Zero To 60, comment in this video follow what I mentioned in your last one - there aren’t a lot of stock engines that’ll take nearly 30psi and never complain. Typically some combination of valve springs, head studs, rods and pistons.
My fear is that you swap the engine and it happens again simply because the stock N54 isn’t designed for that power level.
You could bet on that happening, swap the engine and if your current block/heads are in good condition do the above four items and then really lean on it - 35 or 40 pounds here we come ;)
What’s the big color/texture variation at 7:05 that looks like a missing chuck of metal?
That is what i thought initially, but i think its just carbon build up.
Pour alittle bit of oil on to that cyclinder and see if compression changes.
Defs do a wet test
Nothing out of the ordinary that i can see, the carbon build up seems normal especially for a high miler, leakdown test next but a hunch tells me you're going to end up swapping the head.
Oh and I bought a mower... anyway
Still waiting to find the 2020 ferarri f1 team in that cylinder 4, its unexpected but I've seen it too many timrs
Did you already put a couple ccm of engine oil into it and went with another compression test? Usually that rules out defective piston rings.
I haven’t yet. Purely down to time. I could try that instead of doing the leak down I guess
It's kinda fast and easy done, you immediately see the result. Not much content creation compared to leak down test, unfortunally.
My guess is bent valves. I have a head laying in my garage now with 2 bent valves on cylinder 4. Had the exact same noise and low compression. Has happened to me twice. I'll figure out how to send you a picture after work.
Did you narrow down what was causing it?
bent valves will usually result in no compression at all, or close to it
I did not. Happened on 2 different motors. Put a different head on the last one and no problems yet. At lease 2k miles on it with upper 20s pounds of boost. My compression was reading around 70 with the valves bent. They were bent just enough that they couldn't seal all the way.
I take that back. It happened to 2 different motors. The first motor timing was off when I took it apart. Second motor I'm still using timing was ok
I had this issue, oily spark plug along with low compression, the causes is out of round issue. You need new block or get it rebuilt. I ve noticed you r running aggressive timing too, could be that was your main cause. Do you have a smoke coming out from exhaust?
Nah, no smoke from the exhaust.
@@ZeroTo60Tube Good, waiting for leak down test.
I be the rings have become stuck to the piston and thus they are not sealing properly. These engines can siffer from this especially if you have a particularly dirty cylinder. Stick some seafoam in the cylinder and leave it to soak overnight and you might be suprised
I hope it’s not gonna need a new motor??? But from what it looked like, seems like you maybe fingers crossed 🤞🏽 it’s nothing crazy and you can get away with like a simple re gasket the top?
I just hope the block and crank are all good. I dont mind if i have to use the engine from the e90, but if that is the case i will save up for some stronger internals for this one.
I hear you. But it’s not a bad idea to start disassembling the other n54 now and collet what’s good outta that engine. Then why not maybe start thinking and planning out what parts and turbo or turbos and fuel system and so forth and so on.... ?
Since this motor is so abused just replace it🤷♂️ ... build it right then slap it back in.. your running 28psi on a crap motor its going to break and im sure the transmission is not far behind. Other than trying to grenade a junk motor not sure what your doing just send it blow it up and get on with the swap
Sadly I am searching this because my cylinder 4 is messing up 🙃
I’m coming up tomorrow n Saturday if you have a min let me know
We are flat out, but wouldn't mind putting a face to the name if you have 15 mins spare when you're up.
injector seal
Either way its needs a build. Just pull it apart and rebuild it regardless mate, save messing
It’s all fun and game until the camera gets stuck on the valve and end up pulling the camera off in the cylinder
If it's a ring land, it would be a hairline crack on the ring land(in most cases) . Not something u can see from the top. If you could see it on top it would have been a major knock or lean out event. So it's not that. Hope it's something easy
Look at 3:40 threw 3:50 what was that above you’re house
I’m willing to put a months wages that the ringland is cracked and the oil scraper ring can no longer do it’s job properly which is allowing oil into the combustion chamber.
I like the how you roll! Haha. I think you’re right. I too would bet a months wages, but I’m gonna need to pay to fix this.......
K swap?
The internet would love that wouldn't they. However, watching the boostedboiz just punch out 1000hp k24s like its no ones business is very tempting.
Piston rings can stick when they get dirty. Causing loss of compression. Put injector cleaner in all spark plug holes. Leave to soak overnight. Turn over engine with fuel pump disabled and spark plugs out to eject the excess injector cleaner from the chambers . Then put everything back together.
Then start the car and let it idle until the smoke dies down. Now do another compression test and see if cleaning the rings has cured the low compression.
Have you ever heard of that happening with an N54?
Zero To 60 not personally but I know it is common to the larger BMW engines , especially when they are used mostly for short journeys and don’t get hot enough. Also need to regularly push these engines to the higher revs. The rings get sticky and don’t seal properly. Long oil change intervals don’t help much either. Should be changing the oil once per year or every 5000 miles. Whichever comes first.
I kept getting a strange error message at the start.
It may still be processing, been a mad rush to get it uploaded and i may have made it live a little too soon. Sorry man.
@@ZeroTo60Tube The only thing I can think of is a slightly bent rod, that's if the comp test was accurate.
I hope not.
Did he ever found what it was ?
Cracked piston
Bended rods happen very often it seems, they're not as strong as most people think. It causer the piston to be a little out of shape and get oily. Eventually you get cracked ringlands and massive engine failure... Also see: bmw.spoolstreet.com/threads/n54-failure-335i.311/
Ouch.
I feel like i have read 1000 posts on n54 failures in the last week and i don't think that was one of them, so thanks for posting it. However, Tony from VTT's post on that thread shows some brilliant pics..... Shall we start taking bets on it being that type of ringland failure?
Which is caused by a bent rod....
@@ZeroTo60Tube IDK man, trying to help as much as I can. I just remembered that I saw that post with one oily piston and found that topic... I guess most of the people just keep sending it and only really notice when the engine goes pop... :(
@@ZeroTo60Tube It's the only "logical" explanation I can think of if the compression is lower but holds stable without leaking out, could totally be wrong though as I'm far from an expert.
8:40 that black line looks like a cracked cylinder wall to me
Definitely stuck out to me.
Robert French Likewise. I would pull the head off if that was my car after seeing that.
At 7:46 there's loose carbon.
I'd open the inlet valves and use the camera again. Within 30min you'd have the inlet manifold off and be at the valve seat.
Good luck with it 👍
P.S. - isn't called "bore scope" 👂
Hmmmm... what are your rims??
666m reps
@@ZeroTo60Tube thanks a million
swap the engine and do a rebuild on this one with better internals
maybe its an injector problem
So I was taught that the first pop of a manual compression test tells you the health of the valves and total compression is rings. Your first pops on multiple cylinders look like 💩. I would lead more toward valve wear. Oil starvation high heat maybe a tune on it.
You need to pull belt while plugs are out and spin motor and check for binding
Pull turbos and intake manifold and check for blow by and post cylinder combustion on #4. Those are the last steps before opening the engine all the way.
Not trying to advertise but you can check my Mercedes M157/278 teardowns on IG and see some internal issues. Mine was bent rod causing ring seizure ruining the garbage Silitec liners. It passed manual compression but relative looked like 💩. You could feel it spinning it manually.
TEAM N54 🤞🤞🤞
Imagine the borescope breaking off in the cylinder 🤦🏽♂️😂
Especially that small non magnetic mirror cap..... It did cross my mind, thats for sure.
😣
👍
Getting in to the old content i see!
Did you happen to see what the other known good cylinders look like in comparison to #4? (Srry, at work and couldn't watch the whole vid:)
I havent yet, after the second motor was also down on comp, i stopped to rush to diagnose this. But its in the shed today, ready for work next week.
@@ZeroTo60Tube following closely! Sending good vibes from north Idaho N54 club. Hope it all works out. If you need a new block, one that been worked and ready for a build, let me know. We would donate it to you and you just pay to ship it, we could probably kick in enough to cover most of it;)
@@brandonbelstad6450 Thanks so much. Very very kind of you
Pull your injector 4 out take look
Do you think the injector seal would be noticeably cooked? Also any ideas on the oil in the cylinder?
@@ZeroTo60Tube I think your injector seal is done replace it with new 1 that should fix that problem you having I had similar issues with mine
+1 to this - injector seals do weird things.
🤞🤞🤞
bore-scopes are useless, leak down test stat!
Yo.... why didn't you say this last week.... haha.