went to replace my injector o-rings and when I pulled the fuel rail I noticed a small (1.5-2mm) piece of the cylinder 8 injector had broken off inside my cylinder

and as suspected, o-rings were brittle and cracking

just a heads up to those with this engine. I can’t find anything online about m113 Benz engines having injector problems..

engine runs strong otherwise, I would’ve never known had I not pulled the fuel rail...

being cylinder 8, tells me maybe high exhaust temps caused this issue...

tomorrow morning I’m getting out the compression tester and buying an endoscope to inspect the cylinder. I’ll report back

Figured I’d update this thread

the part that chipped away, turns out is just a plastic o-ring retainer! It was so brittle from age and heat that I barely recognized it. It actually wasn’t until someone from w220 forums on Facebook mentioned it was a disposable part, that I realized the part was removable

There is practically no info on these parts online, and the mercedes dealer will have no idea what you’re talking about if you try to buy parts there. This isn’t even in EPC for some stupid reason. Even Bosch injector rebuild kits don’t include this part.. very strange. I firmly believe these o-ring retainers need changed everytime the fuel rail is pulled, otherwise they get brittle with age and fall apart into the cylinder heads!! Not good at all for the engine to have debris in the cylinders. I also firmly believe that with more mileage, these seals are much more likely to break off inside the cylinder head during fuel rail removal..

what you’re looking for is called “Bosch type 3 injector seal”, some people call them pintel caps, some call them seals, some call them o-ring retainers

the same fellow from the w220 group mentioned that this plastic piece probably isn’t that big of a deal, and while I don’t disagree. I’m really fond of this engine that I dropped in my car. I don’t want to risk bending ANY valves, scoring any cylinders etc so I’ve decided to pull the intake manifold

just my luck, the only two cylinders with intake valves open at this specific time are the ones the broken injector seal piece fell into. Time for plan B (and not the $50 Plan B from CVS)

so ive been fashioning small tubes to the end of vacuum cleaners, removing spark plugs, and blowing in compressed air through the spark plug holes /intake valves to try to stir up the broken injector seal to be sucked into the vacuum

last ditch effort, when everything is re assembled I’ll probably turn the engine over with no fuel injector/spark plugs plugged in and try to “encourage” any debris that fell in the cylinder to fly out the exhaust valves, I’m sure between these methods I’ll have somewhere around 75% success. The idea is to shoot whatever debris possible out the exhaust valves before the injectors and plugs have a chance to burn it/atomize it

see photos for close up pictures of the injector, and the injector “seal”. One photo has a perfectly round seal, the other has a chip removed. This chip is what fell in the 8th cylinder

what started as an o-ring injector job has slowly turned into a full fledged intake manifold removal/injector overhaul. It was a good chance to clean up the inside of my manifold anyways, the thing was filthy inside