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I have the standard rattle at startup from the timing chain tensioners and check valves. I've had it looked at by the dealer in the past and nothing much came of it other than the standard "yeah it's this, it's an expensive repair, won't really cause damage unless you notice it getting worse" so I elected to not do anything at that time. I took it in for a B Service this week and I asked them to take a closer look at price it out. The service tech put this on my invoice, verbatim:
"Quick test and didn't find any codes that would cause an engine rattle. Let vehicle sit and started again could hear rattle from left bank of engine and some on right. Found LI05.10-P-056435 for rattle falling in engine number range. Both upper chain tensioners, check valves, all coolant lines to turbos, thermostat, oil filter housing with gasket, and MB black sealant. Note this motor is very sensitive with its chain tolerance and is hard to relearn with high miles. If noise ends up being something more than check valves it may end up needing a motor."
For anyone that has had this repair done, what came of it? Did the check valves/tensioners fix the issue or is the tech being overly cautious by saying this? I also haven't heard of an engine needing to "relearn" a timing chain (note: engine has 80k on it - is that considered high mileage for this repair?). I told my advisor to just hold off on it and we'll let a sleeping dog lie for now, but I hate having a rattle at start up. It always makes me feel like something is broken even though I know exactly what the issue is.
I've seen cam timing/chain problems on these engines with repairs and less miles than you have. The last one required all new chains which was a engine-out and apart job which I wouldn't wish upon my worst enemy.These engines are fragile and some are failing around the 100-120k mark so I don't think it's worth it to repair anything at 80k. With the GL450's at 100k a replacement engine plus installation is as much or more than the car is worth, for example. How long do you plan on keeping the car? I'd just drive it, and if and when there's a major failure just walk away from it. After all, it's just a depreciating appliance. I would however have the plastic coolant lines replaced. They will break and leak at any point.
Last edited by E55Greasemonkey; Jun 18, 2022 at 08:55 PM.
I'm on the same boat, my car is curently in the garage out of service. I have the rattling/knocking sound for the first 5 seconds and then dissapears. The sound is coming from the left side so I decided to open it up. I found that the chain tensioner on that side is bad and I will have to replace it however I noticed that I don't have check valves installed so I have to ask the dealer if I have to install them. Not totaly sure if my sound is coming from the bad chain tensioner or from a bad camshaft adjuster. Some people have a faulty adjuster that was causing the noise. I'm not sure if I will replace the adjusters because those are a little challening for me because you have to take the whole top off and injectors etc. and make sure I don't mess-up the timing. Does anyone here know how to check the adjusters to see if they're bad and also if anyone can get us a workshop manual on how to replace the adjuster? Thanks in advance.
I have the standard rattle at startup from the timing chain tensioners and check valves. I've had it looked at by the dealer in the past and nothing much came of it other than the standard "yeah it's this, it's an expensive repair, won't really cause damage unless you notice it getting worse" so I elected to not do anything at that time. I took it in for a B Service this week and I asked them to take a closer look at price it out. The service tech put this on my invoice, verbatim:
"Quick test and didn't find any codes that would cause an engine rattle. Let vehicle sit and started again could hear rattle from left bank of engine and some on right. Found LI05.10-P-056435 for rattle falling in engine number range. Both upper chain tensioners, check valves, all coolant lines to turbos, thermostat, oil filter housing with gasket, and MB black sealant. Note this motor is very sensitive with its chain tolerance and is hard to relearn with high miles. If noise ends up being something more than check valves it may end up needing a motor."
For anyone that has had this repair done, what came of it? Did the check valves/tensioners fix the issue or is the tech being overly cautious by saying this? I also haven't heard of an engine needing to "relearn" a timing chain (note: engine has 80k on it - is that considered high mileage for this repair?). I told my advisor to just hold off on it and we'll let a sleeping dog lie for now, but I hate having a rattle at start up. It always makes me feel like something is broken even though I know exactly what the issue is.
Don't wait if you want to have a chance:
Old tensioners leak the oil pressure that's supposed to lubricate the camshafts aluminum journals all the way to rear most.
Good oil change ever 5 to 7kMi help offset the lubrication issues.
The tech was planting the seed with the client that the dealer service dept is preparing to put an engine replacement quote in front of the client.
The “relearn” comment is rubbish. Check valves, new tensioners and new chains all around will solve it. The question is, is the cost palatable.
And as E55 says this engine is fragile, as are most MB engines, so don’t expect high mileage from the M278 or its cousin the M157.
Are these engines really fragile? I hear people calling them bulletproof after a little preventative maintenance. And others saying you can run extremely high hp on them. Is this not true I'm trying to figure out if I should sell or keep my new (to me) cls550.
Are these engines really fragile? I hear people calling them bulletproof after a little preventative maintenance. And others saying you can run extremely high hp on them. Is this not true I'm trying to figure out if I should sell or keep my new (to me) cls550.
Read the posts on this site and form your own opinion. In my view, every MB V8 has fatal issues at or before 100k miles commonly enough for me to give a thumbs-down rating for consumers who want to accumulate high mileage (200k miles and beyond).
The list of fatal flaws and significant headache repairs is long for the M278/M157.
Old thread but.. my engine is number 278928 30 255223. According to the document below tensioners and check valves were already installed. Do I need to do anything to it now? I have occasional cold start rattle for 1-2 seconds. It happens only sometimes at this point. Car is 150 000km. Thanks!
Old thread but.. my engine is number 278928 30 255223. According to the document below tensioners and check valves were already installed. Do I need to do anything to it now? I have occasional cold start rattle for 1-2 seconds. It happens only sometimes at this point. Car is 150 000km. Thanks!
-- Replace both of your old secondary chain tensioners that are now actively leaking oil pressure.
-- Inspect the VVT Phasers for locking pin condition
-- Change your engine oil at 5k.Mi. Max
Thinned oil can rattle even an all new engine.
Thank you very much for your answer! I change the oil every 5k km since I bought the car. I have drove more then 10 000km on it now and made two oil changes myself. I have also unplugged the oil solenoid when i got the car and added the sacrificial pigtails to the cam adjusters (had oil leak in only one of the wire harness). I know it is too much to ask, but can you may be show me where i can get the part IDs for the parts you mention? Or maybe post them here? My VIN is 4JGDF7DE0FA557701.
Just another question. I was told i should also replace the check valves behind the tensioners. Should i do it and is there a way to pull them out from the holes at all? I imagine they are pretty snug in there.
2x Engine Cylinder Head Oil Check Valves - A2780503300
Just another question. I was told i should also replace the check valves behind the tensioners. Should i do it and is there a way to pull them out from the holes at all? I imagine they are pretty snug in there.
2x Engine Cylinder Head Oil Check Valves - A2780503300
GREAT QUESTION... the answer is NOpe!
The factory check-valves can not be removed without a nightmare drilling procedure.
Do not disturb existing check-valves!!
The story is MB used to create additional startup rattling by not installing these "check-valves" up to 2012/13 I believe.
You may want to inspect your leaking CPS camshat sensors while in there.
GREAT QUESTION... the answer is NOpe!
The factory check-valves can not be removed without a nightmare drilling procedure.
Do not disturb existing check-valves!!
The story is MB used to create additional startup rattling by not installing these "check-valves" up to 2012/13 I believe.
You may want to inspect your leaking CPS camshat sensors while in there.
great! And do I need to disconnect the battery while I remove all the **** that is on the cam covers?
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