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Cylinder Head replaced and 1k miles later Rod Bearing failure in a different cylinder
Looking for a little advice. I've, of course talked to ChatGPT about this, but I wanted some of y'all to tell me what you think of my situation.
2021 GLE with odometer at 69k. Started loosing power/misfiring. Took it to my local European repair shop (with ex MB techs/engineers) and cylinder head replacement was proposed. After going thru pros, cons, etc we went forward with repair.
Received car back and it drove fabulously for ~1k miles. Out of the blue we begin hearing very loud clanging noises coming from the bottom of the car. Luckily we were at the house so I parked it and had it towed back to the shop.
After back and forth, removing the oil pan, etc I get a call telling me that there is a Rod Bearing failure in cylinder #4 (initial problem with cylinder head was in #1.)
The shop, unsurprisingly, is telling me that this is totally unrelated. To me this just seems too coincidental. A little research tells you that rod bearings can be affected after a repair like this via improper timing during reassembly, debris getting ito the oiling system, etc.
If there are any techs on here... what is the likelihood that this could happen and NOT be related. Rod bearing failures dont exactly seem to be common on 69k GLEs (unlike the cylinder head) and it just seems all too convenient for them to talk about there is no way this could be related because the heads are on the top of the engine and the bearings are on the bottom.
Thoughts? Any ideas as to how to move forward?
Last edited by Jason Jolly; Jul 23, 2025 at 07:08 PM.
Reason: grammer
I’d be curious how they sealed gaskets. Some folks get a little loose with the silicone. All it takes is a little bit to plug an oil passage.
Would be interesting to pull head and valve covers and look at surfaces. Also oil pickup and oil filter. If there are globs of silicone in there, you know the answer.
What was the reason for the cylinder head failure question mark was it bore scoring or valve related? Cam surfaces?
As mentioned above, one variable is the clogging of oil passages or pick ups with sloppy sealant. This would be absolutely detrimental because you need to figure out if everything is clear and clean such as the oil squirters. you can ask what sealant they used to see if they used the proper product. This is not an engine for “the right stuff”. Beads laid down are usually no more than three millimeters so they do not squeeze into cavities and cure more quickly.
Internal engine repairs always require a lot of trust between the customer and mechanic. I’ve always been fortunate when a mistake transpired down the line that they have been honest about cause and correction… like breaking an nla camshaft during covid. We had to work together to find the part (which I found after searching the entire world and begging a rebuilder to help me out by selling me his stock).
The unfortunate part of this is that you might need to pull and inspect all the bearings and also re-boroscope the cylinders just in case.
When the cylinder head was replaced, did they check anything like oil pressure?
I'm sure a lot of us watch Dave’s Auto Center and hearing his explanations to customers, he always tries to state that a repair today may not mean there is no repair tomorrow and it’s a tight line to walk where everyone gets treated right by having that honest relationship.
I’d recommend to go talk to them in person and maybe have your list of questions written down. See how they can help you out.
Good luck
Last edited by Baltistyle; Jul 23, 2025 at 09:23 PM.
Thank you both. As for a list of questions if y'all have any other suggestions outside of what you've already said I'd love to have them as it's a little over my head at this point and I'm trying to educate myself as much as possible.
I do know that they stated that there was bearing debris in the filter but that's more of an aftereffect.
Here are a few photos that I've been sent. I have a video of the tech moving the bearing back and forth but i can't apparently upload it.
When sending (or before) the sample in to the lab, you should shoot them an email in regards and let them know what the situation is. They may be able to offer some additional / more expansive analysis. By the sound of the damage, you'll definitely see all wear metals spike, but as pointed out earlier you would be looking for the presence of gasket related chemicals to prove a connection that the original repair was the reason.
Personally I use blackstone labs and am happy with their services. There are other companies out there if you want to shop around. Attached is a quick screenshot of their general lab results so you get an understanding of what you'll be looking at. It has comments, and universal averages. I believe if you ask for specifics, they'll be able to tailor labs to fit your needs. Good luck to you.
Last edited by vincheung; Jul 23, 2025 at 11:35 PM.
At this time, I would start looking at the verbiage of your "comprehensive" insurance. While its stated that comprehensive typically does not cover mechanic's negligence, it still MAY apply. For example someone I know personally, had their oil change done, oil plug was not tightened (tech put the plug on by hand, threaded once, got distracted, forgot to tighten, filled oil, car drove off on to highway, oil poured out, engine seized. Comprehensive covered).
As for "suing" the shop. Before going that route, consider starting with a claim against the shop's business general liability insurance. The insurance carrier & policy number may be posted near the shop's city/state licenses, if not, ask the owner for the information. Don't get aggressive about it when asking, keep it soft and dont direct statements of "fault" towards the shop, you can say something like "I'm considering a claim with my insurance broker, and they asked for your shop's general liability insurance company so they could discuss how to properly process it."
Now for actually suing, in civil court (small claims court) you are dealing with "the preponderance of the evidence" and don't necessarily need to "prove" that the shop was negligent. This part of the conversation can be continued with someone more experienced in civil matters, I mainly deal in criminal, but i'm happy to give more insight about it down the line. Consider the above options first.
@vincheung very well put. Nice suggested verbiage about contacting the insurance company. Likely to get a more open, less guarded response. And assistance in finding the cause.
They would have to be really crappy mechanics to RR a head and cause rod bearing or crank bearing issues.
Mains & Rod bearings fail due to lack of oil or too large clearance.
What was your oil pressure when before and after this issue? (hell does MB still put oil pressure gages in the car?)
If only one rod failed, then the galley that feeds the bearing got restricted or clogged starving bearing of oil and hence the bearing to crank contact which kills the bearing.
Or
4th cylinder could be the last inline to get oil from bottom end oil circuit as it tends to go from front to back (not sure on this engine - What engine do you have?
So if your engine was low on oil, or oil pump crapping out, failures would start at the end of the line.
Not sure what you know - but the rod bearing rides on a cushion of engine oil under pressure (hydrodynamic bearing) in the small gap between bearing ID and crank OD.
Pump has pick up strainer to prevent big junk from getting into it and then flows thru filter to clean oil before going out and lubing things.
I doubt what they did caused this issue but maybe the head was not original issue which you have not mentioned yet.
Again unless they are the worst mechanics ever or had a bad day and dropped something down into pan that clogged something.
But if they did mess up, and they now tore engine down - they could have removed any evidence.
Time to cry and call insurance company and praying might help a little bit
if that the pic of you Engine. There is enough "Glitter" in it to require rebuild, or at least a short block. it's all throughout the oil passages. That oil filter housing tells the tale too. I don't see any pics of you cylinder walls so you don't know what scoring occurred from the glitter in the oil.
Last edited by SmokieBehr; Jul 24, 2025 at 07:12 AM.
Make sure you report the head failure to the NHTSA. At some point they may force Mercedes to add the GLE 350 to the extended warranty Mercedes has on that motor for other vehicles that use the same 4 Cyl.
Did you check with Mercedes before you brought the vehicle to an independent mechanic? Mercedes may have offered some sort of assistance to cover a portion of the cost.
Make sure you report the head failure to the NHTSA. At some point they may force Mercedes to add the GLE 350 to the extended warranty Mercedes has on that motor for other vehicles that use the same 4 Cyl.
Did you check with Mercedes before you brought the vehicle to an independent mechanic? Mercedes may have offered some sort of assistance to cover a portion of the cost.
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