Diagnosing Early Black Death

I'm looking for some help in diagnosing the early stages of black death. If the injector seal begins leaking, where does the leak occur? Also, what does the black sludge consist of? Just a mixture of fuel and soot?

I think the injector wells on my sprinter are pretty clean, but the #3 and #4 wells are somewhat dirty. The #5 well definitely has some shiny substance in the bottom of it. Based on the location of the dirt, I think that it may be a leaking air/oil separator. I got that idea from this thread:
https://sprinter-source.com/forum/showthread.php?t=54868
I think that if the injector seal were leaking, the filth would be seen higher up on the injector.

The engine runs great, and I have not noticed any adverse smells. You can definitely smell that the van is running if you are in the area, but I think that is common for diesel engines.

What do ya'll think? I greatly appreciate your advice here, in addition to the extremely informative posts which fill this forum.



2006 Sprinter 3500, 110,XXX miles

run the engine with that cover off and see what is going on. #5 looks questionable. Also touch that goo and see/smell what it is made of.
All in all, I'd say it is something to keep an eye on.

Spray the injectors with soapy water with the engine running, only sure way to know.

It's tough to tell from pictures.

The area in question looks more wet from liquid oil than the beginning of Black Death aka injector seal leakage tar like combustion gases. Is there residue above that injector on the inside of the black plastic cover? Has there ever been any injector changes in the past? If yes the injector valley aluminum cover may have a slight crack with oil seeping out. A casting defect is another maybe less likely possibility.

Soapy water is a good check. I would only use that method on the questionable injectors. I don't know if there is any problem with the soap residue/possible corrosion in the close clearances of the injector wells, but why introduce that if not needed.

Again. It's tough to tell from pictures.

vic

“If the injector seal begins leaking, where does the leak occur?”

Click to expand...

There is a copper crush washer at the lower end of the injector. If this seal fails, partially combusted fuel is able to pass the seal and travels up the gap between the injector body and the bore in the valve cover. The gas then further erodes the copper and the aluminum cover or steel injector body, increasing the leakage. Eventually the passing air/fuel mixture makes a characteristic chuffing sound, much like a steam engine, with a strong odor in the engine bay, and somewhat at the tail pipe though the catalytic system mitigates it.

This guy does a good job of explaining the symptoms at the 1:45 mark (and the fix if you watch the whole hour)
https://m.youtube.com/watch?v=olCtKlRPBZc

“What does the black sludge consist of? Just a mixture of fuel and soot?”

Click to expand...

Yes, but not simply diesel and carbon black. It’s in a form that more resembles burned plastic mixed with roofing tar or asphalt. When hot (150’F) it may soften to a gummy tar, but when cold it is brittle and glassy. A productive leak will condense into tar, and this liquid will be spit out of the bore by the volume of leaking gasses, spraying nearby surfaces. A tiny leak could conceivably produce tar that oozes up the bore and pools in the gallery.

The pool behind #5 deserves more scrutiny. If the black pool is hard then it may be a seal leak, though typically the venting cylinder spews and makes more of a mess of things before producing this much tar over the bore. Allow the engine to reach operating temps (180’F) to soften any tar then inspect the gap around the injector body for seepage. Spraying water and watching for bubbles may help. OR: If the pool is liquid at room temperature then search the area for an oil or fuel system leak, such as a hairline crack in the valve cover or a leak in a return line connection.

-dave

A burned diesel/exhuast smell (usually fairly strong) while driving, or under the hood while idling is a good indicator of a seal leak. Follow up with soapy water. Early leaks have a oil like spray coming from the injector holes. Engine oil will have soot, and usually be black. The partially burned diesel from a leaking seal has a different smell.

Thanks everyone for your help.

Despite my expectations, I was able to jam my little finger into the #5 injector well. To my relief(?), the shiny substance was liquid, and seemed like oil to me. The underside of the injector cover was quite clean. There are no strong smells while driving.

I checked the hoses above the engine, and they seemed clean. The seam on the left of the engine did seem a bit dirty, as though there may be some light seepage.

I think at this point I can be relieved that it's likely not black death. However, I should probably start worrying about a cracked aluminum injector valley, as vic mentioned, or a valve/return line crack, as dave mentioned.

I've cleaned up the area and will occasionally check for oil accumulation.

A couple of remaining questions:
Can I rip off that foam stuff on the underside of the hood? I assume it's some kind of heat shield, but it is disintegrating and getting everywhere.

Do you see any issues with driving around for a bit without the injector cover? If I can remove the deteriorating heat shield thing, then I think that would be ok.

Thanks again for all the help



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I have the same question. 180,000 miles. I check after each oil change. Just returned from 5000 mile down south
Any ideas?

dg55117, do you have any more info? Any pictures of the issue?

That does look like engine oil. My guess is a crack in the valve cover, so I’d swab the area clean, drive it hot for a half hour, then make a close inspection for a source. It doesn’t appear to be a large volume so you’re looking for a SMALL source.

The blanket under the hood is there as a sound and thermal barrier, neither of which is super critical but you may notice more engine noise walking past the nose, and winter warm ups could be extended. But if it’s falling off I’d pull it out before it drops onto something hot and starts a fire.

Running without the injector cover is okay for short periods, but avoid rain or dusty conditions.

Good luck!

-dave

The hood insulation keeps the fresh air intake duct cooler in hot weather.

zifey, did you ever find out where the oil was coming from? Would be curious to see if this was resolved.