2014 GL550 engine knocking noise
#51
Member
Took my 2013 gl550 157k miles into a import shop….Paid $260 for them to tell me it needs a new engine. I asked how did they know..told me they listened to it. I asked did they check cylinder pressures, scope it, etc. Nope. They believe its a rod bearing and it could go out at any time. Today I’ve put 100 miles on it and revved it to 5k rpm just for the heck of it. Still running.
#52
Mine is there under load or not, but when under load its a bit more “tin” like. From inside the car you dont really notice it unless under load.
There’s an engine machine shop local to me with a mechanic connected to their building. I’m going to run it by them to see what their opinion is.
At this point I’m considering doing a drivetrain rebuild and a quick restoration on this thing. For $10k I can pretty easily get this looking like new and last me another 150k miles. That’s less than the cost of depreciation on a new or used one.
There’s an engine machine shop local to me with a mechanic connected to their building. I’m going to run it by them to see what their opinion is.
At this point I’m considering doing a drivetrain rebuild and a quick restoration on this thing. For $10k I can pretty easily get this looking like new and last me another 150k miles. That’s less than the cost of depreciation on a new or used one.
#53
Member
Mine is there under load or not, but when under load its a bit more “tin” like. From inside the car you dont really notice it unless under load.
There’s an engine machine shop local to me with a mechanic connected to their building. I’m going to run it by them to see what their opinion is.
At this point I’m considering doing a drivetrain rebuild and a quick restoration on this thing. For $10k I can pretty easily get this looking like new and last me another 150k miles. That’s less than the cost of depreciation on a new or used one.
There’s an engine machine shop local to me with a mechanic connected to their building. I’m going to run it by them to see what their opinion is.
At this point I’m considering doing a drivetrain rebuild and a quick restoration on this thing. For $10k I can pretty easily get this looking like new and last me another 150k miles. That’s less than the cost of depreciation on a new or used one.
#54
Took mine to a local import mechanic tied to an engine builder/machine shop and they suspect piston slap. I will probably have hime pull the motor and then I’ll send it off to have sleeved..
#55
#57
Member
Mine is still doing it at around 140k, but only when cold. It's gone after 2 min of idling.
One odd thing is that it is much quieter if the car is on an decline with the engine lower than the rest of vehicle. Cam shaft maybe and quieter when more oil on it? At this point I don't really care unless it gets worse and my true diagnosis will be when something fails.
I really need to check my cam mags and sensors for oil....
One odd thing is that it is much quieter if the car is on an decline with the engine lower than the rest of vehicle. Cam shaft maybe and quieter when more oil on it? At this point I don't really care unless it gets worse and my true diagnosis will be when something fails.
I really need to check my cam mags and sensors for oil....
#58
Member
Mine is still doing it at around 140k, but only when cold. It's gone after 2 min of idling.
One odd thing is that it is much quieter if the car is on an decline with the engine lower than the rest of vehicle. Cam shaft maybe and quieter when more oil on it? At this point I don't really care unless it gets worse and my true diagnosis will be when something fails.
I really need to check my cam mags and sensors for oil....
One odd thing is that it is much quieter if the car is on an decline with the engine lower than the rest of vehicle. Cam shaft maybe and quieter when more oil on it? At this point I don't really care unless it gets worse and my true diagnosis will be when something fails.
I really need to check my cam mags and sensors for oil....
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mcoady1 (09-07-2023)
#59
Took my 2013 gl550 157k miles into a import shop….Paid $260 for them to tell me it needs a new engine. I asked how did they know..told me they listened to it. I asked did they check cylinder pressures, scope it, etc. Nope. They believe its a rod bearing and it could go out at any time. Today I’ve put 100 miles on it and revved it to 5k rpm just for the heck of it. Still running.
#61
Member
Hey all- M278 here in a '15 S550. Came across this thread re: knocking. I have a deeper sounding knock only on a hot restart, but after the car sits for 10 mins or so. It instantly goes away on startup after 1-2 seconds which I presume is the oil pressure building up. It does not knock if I stop and restart quickly.
Guess my question is, w piston slap, would it go away instantly once oil pressure builds? I'm guessing I may have some sloppy rod bearings perhaps that clears once pressure builds.
Car has 63k on it. I bought it w 45k 2 years ago. And noise has not changed/ worsened. Oil changes at 3-5K since I've owned and seems well maintained by other owner. Once the knocks clear after couple seconds the engine is whisper quiet, no taps etc.
Guess my question is, w piston slap, would it go away instantly once oil pressure builds? I'm guessing I may have some sloppy rod bearings perhaps that clears once pressure builds.
Car has 63k on it. I bought it w 45k 2 years ago. And noise has not changed/ worsened. Oil changes at 3-5K since I've owned and seems well maintained by other owner. Once the knocks clear after couple seconds the engine is whisper quiet, no taps etc.
#62
Member
Hey all- M278 here in a '15 S550. Came across this thread re: knocking. I have a deeper sounding knock only on a hot restart, but after the car sits for 10 mins or so. It instantly goes away on startup after 1-2 seconds which I presume is the oil pressure building up. It does not knock if I stop and restart quickly.
Guess my question is, w piston slap, would it go away instantly once oil pressure builds? I'm guessing I may have some sloppy rod bearings perhaps that clears once pressure builds.
Car has 63k on it. I bought it w 45k 2 years ago. And noise has not changed/ worsened. Oil changes at 3-5K since I've owned and seems well maintained by other owner. Once the knocks clear after couple seconds the engine is whisper quiet, no taps etc.
Guess my question is, w piston slap, would it go away instantly once oil pressure builds? I'm guessing I may have some sloppy rod bearings perhaps that clears once pressure builds.
Car has 63k on it. I bought it w 45k 2 years ago. And noise has not changed/ worsened. Oil changes at 3-5K since I've owned and seems well maintained by other owner. Once the knocks clear after couple seconds the engine is whisper quiet, no taps etc.
#63
Member
If you've ever restarted after an oil change, and get a low end clinking before the pressure builds, it's like that. I will definitely get an audio of it and share. Thank you!
#64
Member
#65
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2014 GL450, 1992 W140 300SD, 1993 W140 300SE, 1987 E30 Convertible
Actuator has pin which keep it from turning till the oil pressure buildup in upper area. That pin wears out letting actuator fly around.
#66
That's exactly the kind of noise I'm referring to. I've heard it many times especially after frontend timing/tensioner/cam actuator work before the oil pressure is primed. It's very likely the tensioner hammering due to lack of oil from ineffective check valve. If you were to see this in action you'll see the tensioner piston pulsating in and out as the chain rolls. I've listened to MB service audio that claims a defective cam actuator can cause similar noise. Do you know if yours have the updated tensioner and check valve? BTW I'll trade my knocking for this one any day if that's what it is...
A few observations: Like some others here, the knocking speed corresponds to RPMs. When I'm driving and take my foot off the gas to coast, the knocking disappears completely and only comes back when the car slows way down to nearly a stop. The knocking starts immediately upon ignition and is loud and obvious at idle. It gets both faster and louder during acceleration. However, if I park the GL and put it in neutral and rev it a bit, the knocking disappears completely around 1600 RPM! I don't know a ton about cars, but this is such a mystery, and I would love to know if someone has figured it out. I don't know if I should bail on this vehicle while it still runs, or if there is still hope for it. Would love to have the advice of any knowledgable folks on this forum.
#67
Bro, mine also same, my mechanic said its a common issue with this model. i sent an email to German head office requesting for recall hehehehe, i know this is not going to happen at all. i have driven 3k miles with the noice.
#69
Member
- When I started the engine after new tensioner installation, it rattle/knocked badly for quite sometime. I shut off the engine immediately wondering what the issue was.
- When I inspected it I discovered the noise was coming from the brand new tensioner. I removed it, put the old one back and it too made the same noise. There was no such noise before the repair (car only needed camshaft but I also replaced the tensioner while in there).
- I later realized that it's normal behavior until the tensioner is primed with oil pressure so I put the new tensioner back, let the car run for about 30 seconds and then the noise disappeared.
So, is it possible that the oil passage to the tensioner is clogged or defective or has defective check valve that prevents full hydraulic pressure on the tensioner? My noise get much worse when oil level is low. I have scored cylinder walls and oil burning problem which I'm not sure is related to the knocking noise. I can tell when my oil level is getting low by how prominent the noise becomes at idle and low speed.
Last edited by tadiguy; 11-14-2023 at 11:18 PM.
#71
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2014 GL450, 1992 W140 300SD, 1993 W140 300SE, 1987 E30 Convertible
The knocking noise saga. comes to the end. Two major factors contributing to it
1) Wear of tensioner (internally) - usually stuck due to wear and easy as temperature goes up
2) Wear of camshaft lobes - both or exhaust camshaft on driver side goes bad causing knocking noise as it goes due to grooves on lobes - basically rocker arms jumping in and out of grooves unable to compensate for lash.
Service adviser will advise to change timing chain and adjusters were real reasons mentioned above.
1) Wear of tensioner (internally) - usually stuck due to wear and easy as temperature goes up
2) Wear of camshaft lobes - both or exhaust camshaft on driver side goes bad causing knocking noise as it goes due to grooves on lobes - basically rocker arms jumping in and out of grooves unable to compensate for lash.
Service adviser will advise to change timing chain and adjusters were real reasons mentioned above.
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mcoady1 (11-21-2023)
#72
Member
When I cold start mine later I'm going to try to deactivate a few drivers side cylinders one at a time to see if that is of any help here (with iCarsoft). Mine definitely sounds like its from top of engine near Cylinder 5-6 area.
@tadiguy did you replace check valves with updated design or just tensioner?
@tadiguy did you replace check valves with updated design or just tensioner?
#73
Member
The knocking noise saga. comes to the end. Two major factors contributing to it
1) Wear of tensioner (internally) - usually stuck due to wear and easy as temperature goes up
2) Wear of camshaft lobes - both or exhaust camshaft on driver side goes bad causing knocking noise as it goes due to grooves on lobes - basically rocker arms jumping in and out of grooves unable to compensate for lash.
Service adviser will advise to change timing chain and adjusters were real reasons mentioned above.
1) Wear of tensioner (internally) - usually stuck due to wear and easy as temperature goes up
2) Wear of camshaft lobes - both or exhaust camshaft on driver side goes bad causing knocking noise as it goes due to grooves on lobes - basically rocker arms jumping in and out of grooves unable to compensate for lash.
Service adviser will advise to change timing chain and adjusters were real reasons mentioned above.
1) I replaced the tensioner with one I had pulled from another GL that wasn't making any noise and that didn't help.
2) My camshaft lobes showed no visible sign of wear. However, I replaced both the intake and exhaust camshafts and cam adjusters and that didn't make a difference.
I also replaced all lifters and rocker arms with brand new OE parts as well as the tensioner.
The intake cam adjuster was new aftermarket, the intake shaft was pulled from a GL due to bad tone ring, the tensioner was pulled from a working GL during camshaft replacement, and the exhaust camshaft/adjuster were used from the Bay. There is a small chance that one of these used parts had the exact same problem I'm trying eliminate but as you know, new ones cost and arm and a leg and so I wasn't ready to throw more money and parts at the problem if I'm not confident it will resolve it.
#74
Member
@tadiguy did you replace check valves with updated design or just tensioner?[/QUOTE]
No, I didn't replace the check valves. I bought it used so I don't know if the check valve was ever updated. However, the bolts holding the upper timing chain cover had blue paint on them which I understand from reading MB service bulletin means they've been updated (someone correct me if that's wrong).
BTW: Selectively shutting down cylinders with Xentry, disconnecting coils, fuel injector, etc. didn't help in my case, but your symptoms are a little different (i.e. noise disappears after 2 min) so it will be an interesting experiments. Let's know.
No, I didn't replace the check valves. I bought it used so I don't know if the check valve was ever updated. However, the bolts holding the upper timing chain cover had blue paint on them which I understand from reading MB service bulletin means they've been updated (someone correct me if that's wrong).
BTW: Selectively shutting down cylinders with Xentry, disconnecting coils, fuel injector, etc. didn't help in my case, but your symptoms are a little different (i.e. noise disappears after 2 min) so it will be an interesting experiments. Let's know.
#75
Member
I shut off the injector after the car had been sitting (wouldn't let me on cold start because coolant temp), and it still knocked.
Accessed 'Smooth Operation of Combustion Engine' menu and Cylinder 5 jumps to +/- 3.5 and others hover around +/- 0.5. Not sure if related to knocking, but going to check injector connection etc for oil since I just found my cam sensors to be wet with oil.
Accessed 'Smooth Operation of Combustion Engine' menu and Cylinder 5 jumps to +/- 3.5 and others hover around +/- 0.5. Not sure if related to knocking, but going to check injector connection etc for oil since I just found my cam sensors to be wet with oil.