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Hello,
I recently got a really nice W221 facelift. Car is S450 4matic, well equipped. Has 260 k kms. No errors on any of the modules (I have a Star C4 as a hobby). Car has been sitting at the seller for almost a year, probably has seen a lot of cold starts. Has been serviced every year, last service was 3000km ago.
Engine runs quite and smooth, has a lot of power also.
I decided to change the spark plugs and do endoscopic inspection of the cylinders - as I've heard that these engines are prone to cylinder scoring.
Some of the plugs were hard to undue the first few turns, which was not the case with my other cars. On the endoscope I saw clean and mirror like surface of the cylinder walls with the exception of the lower side where probably gravity has gathered some strange particles on the wall and the piston edge. I provided pictures of the particles - also there are slight wear marks but I believe these are okay for the 260k kms that the engine did
What could these particles be from? Carbon deposits, something from the spark plugs or probable issue with the intake manifold? Do they deserve engine disassembly to clean up?
Thanks for your opinions,
Rado
Last edited by rado.penev; 07-31-2023 at 04:26 PM.
I think you are over thinking things - if granddad never ripped it - it will run like a dog and have crud everywhere - if you use nasty fuel and rag to death you'll have a lot less and might have some damage as the engine struggles to control nasty fuel you shouldn't be using - FYI that top photo of a piston looks strange its FAR to clean - that isn't normal
what water, oil, budget fuel and pollution gets in there and how badly it burns is going to make everything look different - if it runs and doesn't use oil or water just drive it
at 260K km at best its at least 50% dead - there are plenty not ever going back on the road with far less than 60k miles up - so many things to go wrong that cost more than the car is worth, means I bet >75% made are off the road for good with vastly lower miles than yours
this could be a clue - if the circular bit bottom left is corrosion, and of the cyl bore electroplating failing - that might burn strange - if so that engine is game over
Yeah, probably the endoscope inspection took things too far. There is a lot of carbon buildup on the exhaust valves and probably this debris is from them. I will check if the manifold flaps rotate easily and if so will just drive the car for a while with high quality fuel, already changed the oil with Ravenol VST and check after a few months.
this could be a clue - if the circular bit bottom left is corrosion, and of the cyl bore electroplating failing - that might burn strange - if so that engine is game over
Seems these are just the particles staying on the bore, I've seen scored walls of this type of engine and they look very different.
Also the cylinder is alusil, which does not produce rust with such a color.
its might be a water mark from a puddle that was in that cyl !
drive it and keep fingers crossed - or - if you have done decent miles since - and you take a brave pill have another look - at least u'd know if it got over itself ?
Thanks for the opinions. I just bought the car imported from Germany. Did 100 km only. Yes, it's possible to be water, I will monitor the coolant level.
I will check the left bank this weekend also.
I didn't say coolant - some cars will sweat - if this is one of the cyl which ended up with the exhaust valve open it could build up a puddle of condensation in a year
I didn't say coolant - some cars will sweat - if this is one of the cyl which ended up with the exhaust valve open it could build up a puddle of condensation in a year
Seems like a very good reason to exercise our junk with regularity.
Silitec (Alusil) based engines have no coating like Nikasil ones. Instead they are made of alusil alloy, it's aluminium mixed with silicon. There's nothing to wear like that from such a bore. When they wear it looks like that:
there were two types used by Merc on the early cars - one went wrong and they swapped to another - not sure - I prefer cast iron stuff - you got more opportunity for abuse / repair
I don't know much about funny stuff - except if you have an AMG and chip it you tend to bend the rods shortly afterwards - and animals repair by pushing a iron liner on the one pot that nipped up (bending the rod). Then out it fast - because they don't like the cost of doing it properly - as a whole new block, a rod, piston and some gaskets comes in < 25k US$
the pic you gave still looks like pitting of a surface ?
07-31-2023, 04:23 PM
