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This is what the garage has sent me claiming the engine has failed completely on its own and has had nothing to do with them.
This is an OM642 engine with 120K miles on the clock. The car itself is a 2010 plate Mercedes s class W221 facelift
Here is a timeline of what’s happened.
1. We sent the car off for an oil cooler replacement due to a major oil leak. (Garage confirmed it was safe to drive and the level of oil at the time of inspection was good)
2. Garage replaced the cooler, and took the car out for an extended test drive during which the engine came to a complete halt on the motorway with no prior warnings and no signs on the dash.
Garage claims that the car had run for 40 minutes before the engine became seized. Total distance of the test drive should be around 8 miles at best.
Garage is blaming on the soot and sludge buildup and the ‘lack of maintenance’.
The last oil change was done slightly over 1 year ago but the car was practically never driven in between apart from someone starting it up from time to time.
Can anyone please shed some light on whose fault it is and what’s happened with the engine in the photos?
if you run cheap fuels it often leads to the piston rings gumming up - and that stops one of the piston rings main tasks from happening. they have two roles. 1) help seal so combustion gases turn the bang in to power 2) is the main method an engine has for the thermal transfer from the piston crown and into the engine block and its cooling system
No I’m certain it’s had nothing to do with the fuel. Im trying to ascertain if the garage is trying to avoid taking responsibility or if it just naturally happened
if we go back to why the garage were working on it....
why was the oil cooler being changed - leaking ? engine's can take massive abuse - the more gently you abuse, the longer it lasts - but one is still trashing what’s in there - if I top up the oil before asking them to fix a leak that doesn't mean the engine is healthy inside
you can see the piston in one of your photos has smeared down the bore - as that seized slowly, it puts massive stress into the big end bearings you show that are also trashed
I have no doubt the garage gave the car some exercise - they do that - its their reward for hours of hell working on crap - if the car was serviceable it should have operated normally - and the exercise would have helped
if the car has 100% std engine management (no bodge on maps or tuning it to death) and an auto box - no matter how hard they try the car should return happy
the fact it hasn't could suggest
1) it been remapped and they over did it being a little over enthusiastic
2) the car has been operated for a very long time with low oil quantity - and remembering low oil = hot oil, and that hot oil wears out - we can easily get consistent long term damage - top up now and then, and drive a tractor slow it might last thousands of miles longer - but its still dead inside
The car is completely stock and factory. Oil level was fine as we were concerned about it on our return to the vehicle and checked it (slightly over the midpoint between min and max) before the service was carried out.
The car wasn’t run for a couple of months after the previous service as we were abroad. We left the car with the security so it could be started from time to time and are certain the car wasn’t driven much.
check this out - it shows alongside the pic we have of the cylinder bores - that the bore and most of the piston is in great shape (although it needs a pic with it turned 90 degrees to see the area of the piston that actually matters) - it suggest the wear one would expect with time and normal use is not there at all
what I see is massive localised heating of the top of the piston around its rings - this is the piston crown getting too hot because the rings haven't thrown the heat away - that is why my first post says nasty fuel - it make the rings stick and causes the problem in this photo
Pistons clearly show major lack of lubrication. The shop replaced the engine oil cooler. Was it plugged up and prevented lubrication.
does someone know if oil pressure sensor is before or after the cooler? Plugged or partially plugged cooler would keep pressure up for sure but oil flow to lubrication needing parts is compromised.
For cooler replacement I assume oil did not need draining. If it did then did they fill it up again after work was done.
the top of the piston doesn't really get lube - the rings leave the merest hint of lube above them - and that will be there no matter what unless the sump is empty - and on a tractor the fuel is oil giving another source of lube - gummed rings can drive the lack of heat transfer - which I think drove exceptional piston temps - maybe the security boys took it for joy rides and mistakenly topped it up with petrol
my guess is the bottom end gave up when the seizure of the pistons broke down the tiny oil film keeping the big ends safe and it all ends in tears
I do not know enough about how tractors fail under abuse when run on petrol - but of course high combustion pressure from running petrol ??? would also stress the bottom end more than normal - that said I gather petrol cars oddly seem to hate running on tractor fuel more than tractors fear petrol
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