Ran into an alarming issue - OM606 - PeachParts Mercedes-Benz Forum

jake12tech · #1 07-14-2022, 10:06 PM

Need help from the gurus more experienced than me with motors. I’m tearing down my om606 with 430k due to a dead misfire. The car sounded like it was leaking compression in between the head on the exhaust side. I picked the car up as is. The car was at some shop, for sometime before it ended up at another shop. They chucked in an injector at the problem at some point. Who knows why they did that thinking that would fix it.

What scares me about this is, I drained 12 quarts of oil out of it. It was thin and smelled like fuel. That was awfully scary. So, where I’m at now I’m wondering if I should continue going with this. I have to remove the head to see the damage. Is it worth getting all the valves closed and blowing some air into the injector well while I have all the injectors out to see where I hear a leak coming out of? I’m tinning some serious damage could’ve been done to this cylinder.

jay_bob · #2 07-14-2022, 11:01 PM

I would start with the leak down test and then a compression test and see where you’re at.

Stuck injector leaking fuel down into the crankcase can cause some serious damage. Hopefully the piston is ok.

jake12tech · #3 07-15-2022, 05:54 AM

Quote:

Originally Posted by jay_bob

I would start with the leak down test and then a compression test and see where you’re at.

Stuck injector leaking fuel down into the crankcase can cause some serious damage. Hopefully the piston is ok.

Yeah that’s what I was thinking… cracked piston maybe. I’m gonna order the injector adapter from Benz ($117) to test the compression through there instead of the glow plug holes since I have no faith in getting those out.

engatwork · #4 07-15-2022, 06:04 AM

If you tear into it I'd be curious to find out what kind of condition the slide tensioner for the oil pump chain is in. I'm thinking that is the slide rail that will show the most wear.

jake12tech · #5 07-15-2022, 07:29 AM

Quote:

Originally Posted by engatwork

If you tear into it I'd be curious to find out what kind of condition the slide tensioner for the oil pump chain is in. I'm thinking that is the slide rail that will show the most wear.

Yeah I may continue with this a little bit. I am extremely curious at this point what’s up. Is there any chance you can view the top of the piston with a camera through the intake valve? I really doubt it short of pulling the prechamber but optimistic thinking. I’ve removed the oil lines for the filter housing, and a few other things. And to crank it up for a leak down, I’d have to refill it with oil.

ah-kay · #6 07-15-2022, 08:56 AM

I am not engine expert but have been around om60x engines for a long time. Your problems seems to be stuck piston rings. I would do a compression test and go from there.

If you have not dismantled anything yet then I would fill engine with oil, correct level, and fire it up. Check for misfire then do a hot compression test. It is impossible to have 12Q, diesel plus oil, even with the injectors leaking like a sieve. Also you can not check the pistons surface with a camera unless you pull the prechamber.

Good luck.

dieselbenz1 · #7 07-15-2022, 10:22 AM

A failed lift pump will dump lots of diesel I to the engine oil.

ah-kay · #8 07-15-2022, 10:34 AM

Quote:

Originally Posted by dieselbenz1

A failed lift pump will dump lots of diesel I to the engine oil.

If it was the lift pump then it is leaking through the push rod. Possible? of course. But in practice, a few quarts, unlikely.

Anything is possible, include leaking through IP but I would discount them for now.

jake12tech · #9 07-15-2022, 11:54 AM

Quote:

Originally Posted by ah-kay

I am not engine expert but have been around om60x engines for a long time. Your problems seems to be stuck piston rings. I would do a compression test and go from there.

If you have not dismantled anything yet then I would fill engine with oil, correct level, and fire it up. Check for misfire then do a hot compression test. It is impossible to have 12Q, diesel plus oil, even with the injectors leaking like a sieve. Also you can not check the pistons surface with a camera unless you pull the prechamber.

Good luck.

Got it. To me if I had to guess I am no expert if it’s a set of rings stuck, it would be heavy carbon deposit. The injectors looked original, just based off the nozzle having “France” stamped on it. The OEM original manufacturer for Bosch nozzles at some point. I did send the injectors out for a free test in Maryland at JG Parks. I figured that as well, with the prechamber being the obstacle. When I get the injectors back, I’m buying the Mercedes’ injection adapter to do the test that way, short of pulling stuck plugs that’ll break. I guess that’s next in the agenda. I will update this post next week, for anyone that’s curious and any guidance I may need next.

ah-kay · #10 07-15-2022, 01:01 PM

If the engine runs reasonably but missing at idle then I would suspect stuck rings. Very likely with 400+k miles. I would take the head off, take the sump off, undo the rod bearing and push the pistons out from the bottom. Scrape all carbon off, clean the piston groves. Inspect the rings, replace if necessary. Check rod bearings and replace if necessary. Reinstall everything with new head gasket. I have done mini overhaul on the om603 with very good results. However it is your call. Good luck.

dieselbenz1 · #11 07-15-2022, 01:33 PM

Ift pumps move 1 L per minute as tested by others. When my lift pump went bad I happened to notice my fuel was black. I was checking it daily at the time. One 20 k trip the engine oil increased by a few L. I imagine if I left it that would have resulted in a hydro lock.

ah-kay · #12 07-15-2022, 02:16 PM

Take a look at how the lift pump works. Fuel will not spool into the sump in litres through the push rod.

dieselbenz1 · #13 07-15-2022, 07:03 PM

It's not rocket science it's happened to several on this board including me.

ah-kay · #14 07-15-2022, 07:18 PM

Quote:

Originally Posted by dieselbenz1

It's not rocket science it's happened to several on this board including me.

Without disrespect. I know it is not rocket science, it is only a car after all. If you can find a link to a forum member who had issues with the lift pump then I will eat my humble pie. Or any Google link.

jake12tech · #15 07-16-2022, 08:34 AM

Quote:

Originally Posted by ah-kay

If the engine runs reasonably but missing at idle then I would suspect stuck rings. Very likely with 400+k miles. I would take the head off, take the sump off, undo the rod bearing and push the pistons out from the bottom. Scrape all carbon off, clean the piston groves. Inspect the rings, replace if necessary. Check rod bearings and replace if necessary. Reinstall everything with new head gasket. I have done mini overhaul on the om603 with very good results. However it is your call. Good luck.

I am game to do anything really to keep this puppy on the road. The car itself is pretty decent and the price of om606 motors being $4k is insane. What caused your rings to stick? And how did you come up with the diagnosis? Once it came apart? Did you send your block out for any machine work? They’re chrome rings right on these motor?