Hoping there are some fellow M272 (3.0 and 3.5) owners around here that may have some input on the "normal" hot start rod knock that seems to afflict these otherwise pretty fantastic engines.
Bought my '09 C300 w/~62k miles on it last August which has been maintained pretty well by both Mercedes dealers and independent Mercedes mechanics so it has seen probably 5W-40 and 0W-40 its entire life. Appears one oil change was extended to ~12k miles (vs 10k) but with a 8+ quart sump I am sure there was no ill effects from this one oversight.
Problem is that when engine is shut down at operating temperatures it will knock pretty heavy if you start it anywhere from ~1 hour to ~5-6 hours later. If the engine has plenty of time to cool (8+ hours) it won't knock at all and does not knock on a morning cold start. Mercedes has told multiple owners it is normal and reading online it appears this issue comes to light almost from new, some owners have had luck with MB performing repairs and there are photos of the affected bearings that show significant scoring and wear. Apparently most engines had improperly sized bearings installed so the fix is to replace all the rod bearings with tighter tolerance bearings.
I have an extended warranty going through the next 2 years and I believe I have a $100 deductible. My annual oil change is coming up in the next 60 days, so my question is should I even try to get MB to address this or am I in for a fight? Currently at ~73.5k and oil was last changed at ~65k, won't hit the 10k mark on this change as I did not drive enough so looking at ~9k on this oil run.
Any other M272 owners have this successfully fixed by MB under warranty or extended warranty? I don't have the time or patience to fight the dealership or my extended warranty company on this. Seems there are some high mileage M272 that have had this issue from new with no major ill effects later in life, sounds like the old GM piston slap issue where it is obnoxious but does not seem to significantly impact its lifespan.
Bought my '09 C300 w/~62k miles on it last August which has been maintained pretty well by both Mercedes dealers and independent Mercedes mechanics so it has seen probably 5W-40 and 0W-40 its entire life. Appears one oil change was extended to ~12k miles (vs 10k) but with a 8+ quart sump I am sure there was no ill effects from this one oversight.
Problem is that when engine is shut down at operating temperatures it will knock pretty heavy if you start it anywhere from ~1 hour to ~5-6 hours later. If the engine has plenty of time to cool (8+ hours) it won't knock at all and does not knock on a morning cold start. Mercedes has told multiple owners it is normal and reading online it appears this issue comes to light almost from new, some owners have had luck with MB performing repairs and there are photos of the affected bearings that show significant scoring and wear. Apparently most engines had improperly sized bearings installed so the fix is to replace all the rod bearings with tighter tolerance bearings.
I have an extended warranty going through the next 2 years and I believe I have a $100 deductible. My annual oil change is coming up in the next 60 days, so my question is should I even try to get MB to address this or am I in for a fight? Currently at ~73.5k and oil was last changed at ~65k, won't hit the 10k mark on this change as I did not drive enough so looking at ~9k on this oil run.
Any other M272 owners have this successfully fixed by MB under warranty or extended warranty? I don't have the time or patience to fight the dealership or my extended warranty company on this. Seems there are some high mileage M272 that have had this issue from new with no major ill effects later in life, sounds like the old GM piston slap issue where it is obnoxious but does not seem to significantly impact its lifespan.