Crankcase Full Of Fuel. 1991 350SDL - PeachParts Mercedes-Benz Forum

Squiggle Dog · #1 01-06-2015, 05:27 PM

My friend was in need of a car since his was wearing out and had no air conditioning (in Phoenix, Arizona, land of 120F degree Summers). GregMN donated his 1991 350SDL to the cause.

The engine wasn't idling well and had no power for the first several seconds of acceleration. I felt a refurbishment of the fuel system was in order. I have spent almost all of my free time for the past few months replacing all the hoses, filters, and O-rings. I also removed and cleaned the intake manifold, replaced the glow plugs, straightened the hard lines and installed new clips... I've done a lot of work to it.

Today was going to be the day I would reap the fruits of my labors. I put some diesel purge in a can and cranked over the engine. It took lots and lots of cranking until finally the fuel started leaking down the tops of the injectors. I tightened up the hard lines and then cranked over the engine.

It sputtered a bit and finally started to run. Then it sputtered again and the engine locked up. It seems to be seized. The shutoff lever was pushed down nearly in the off position and required some force to push it back up, but then it would spring back down.

I saw dark fluid running out from underneath the car, but all of the hoses were dry. Odd. It appears the fluid is coming from the front crank seal, gasket on the side of the oil pan, the exhaust pipe clamps, and between where the injection pump meets the block.

Then I checked the dipstick. It was extremely overfull with a very thin liquid. It smells like diesel purge. What the heck happened?

It appears that the crankcase is extremely overfull with diesel purge, yet less than half a can actually was sucked up.

I have a feeling that the engine is done for. I am feeling really sick right now. I don't know how my friend is going to react.

mannys9130 · #2 01-06-2015, 05:47 PM

I believe the only path for fuel to oil is via the lift pump or one of the IP pump elements. I know oil can get into the fuel tank through a ruptured lift pump. Is the opposite true? I'm not sure, but that's where I'd look first. Drain the sump and fill with fresh oil first. Then suck some diesel out of the fuel tank and see if it's black and dark in color.

Squiggle Dog · #3 01-06-2015, 05:52 PM

The fuel tank is completely empty because I cleaned it and the screen, as well as replaced the hoses coming from it. I just had diesel purge in a can with the fuel hoses connected to it. I'll take a look in the can.

What really worries me is that the engine is seized up (maybe from the diesel purge thinning down the oil). I don't know if anything but a rebuild can be done at this point.

Diesel911 · #4 01-06-2015, 09:16 PM

Quote:

Originally Posted by mannys9130

I believe the only path for fuel to oil is via the lift pump or one of the IP pump elements. I know oil can get into the fuel tank through a ruptured lift pump. Is the opposite true? I'm not sure, but that's where I'd look first. Drain the sump and fill with fresh oil first. Then suck some diesel out of the fuel tank and see if it's black and dark in color.

X2.
In this last 3 Years more then few people have manged to pull the Element Barrels up and out of the slot and Pin that are line the barrels up when they chaged the Crush Washer and the Delivery Valve O-rings.

The Fuel Supply/Lift Pump has a little 5mm ID O-ring that seperates the Fuel From the Oil inside of the Fuel Injection Pump. If Fuel comes out it is going to mix with the Oil and drain down into the Crankcase.

I suppose if some dirt got into the Fuel Injection Hard Line and made it into the Fuel Injector and held the Nozzke Pintel open that it would not take much raw Fuel from that to lock up the Engine; but, there would have been a noticable miss if that happed.

leathermang · #5 01-06-2015, 06:24 PM

Although that engine is out of my FSM range...
just from being a long time mechanic I really doubt that that much diesel purge could have compromised the oil so much and so fast that that caused the engine to seize... for instance by taking away the lubrication from the bearings.....
So keep looking before panicking...
Only attempt to turn the engine over with a torque wrench applied to the front of the crankshaft... BY hand........ and report the amount required... or if it is totally seized...

ALSO.... check your radiator to see if you have lost any coolant...

Put another car with a hot exhaust next to this car....
pull the dipstick out and drip on the hot exhaust pipe... if it sizzles... it has water in it.. if it blows the hood off the car it is diesel purge...
just kidding about the latter...

Mxfrank · #6 01-06-2015, 09:00 PM

First thing to do is to remove the injectors and see if it will turn. If it does, then check your compression, fuel may be getting past the rings. Finally, pop test the injectors. You may have a leaky injector, which caused fluid lock. If you didn't bend a rod, it may yet live.

Diesel911 · #7 01-06-2015, 09:23 PM

You could drain out the Oil to see if anything abnormal comes out.

ah-kay · #8 01-06-2015, 09:24 PM

Don't be despair. I doubt the engine seized up. I had experienced worst - oil chain snapped and I kept driving without noticing it, engine seized, period. I have since overhauled the engine with the block in the car so anything is possible.

I suspect you have a fluid lock in one or more of the cylinder. This is what I would do, remove all injectors and spin the engine, if it can be spun at all. If coolant or fuel comes out from the hole then it was fluid lock. If it would not spin then it IS a serious problem. Turn to turn it by hand and see what is binding it.

I also doubt the fuel somehow ends up in the crankcase. It is possible but not in the volume you are talking about. How can 1/2 a can of diesel purge fill up your crank case. It is physically impossible.

Diesel911 · #9 01-08-2015, 02:02 AM

Turn the Engine by hand till you know it can be rotated without being stopped by something.

Squiggle Dog · #10 01-08-2015, 08:56 AM

I removed the injectors and could see that the #2 cylinder was full of diesel purge. So it was hydrolocked. I'm not sure about the other cylinders, but the #2 was near the top of its stroke, so that one was obvious.

I cranked over the engine and it turned freely, shooting out diesel purge all over. So, at least the engine is not seized. But now I have to figure out where the malfunction is, or if it's just the way I had bled the system with the stop lever wedged in full flow and not having all of the lines cracked at the same time.

I know that the injectors are closed until a certain fuel pressure (like 143bar) is reached, which causes the spring inside to yield and fuel sprays out. If there was dirt in an injector, and it was stuck open, then fuel would be constantly drizzling or spraying out, but I don't think the volume would be any higher than normal because that is regulated by the pump.

Maybe I messed up something when I replaced the O-rings and crush washers in the delivery valves of the pump. When I put the bodies back in, they all were exactly the same height and I torqued them in 3 stages.

The coolant in the expansion tank is still full and I see no traces of oil. The fluid in the crankcase smells like diesel purge and is the same consistency. It doesn't look anything like coolant, which would make the oil a milky color. The diesel purge was inside of the intake and exhaust manifolds as well. Some of the diesel purge got blown into the manifolds, and some got blown into the crankcase. And some stayed in the cylinders. The tank that was holding the diesel purge still looks clear.

In short, I have to determine if the fuel pump is functioning properly. Then I have to determine if the injectors are functioning properly.

Squiggle Dog · #11 01-08-2015, 09:32 AM

Also, here are the compression numbers from just after removing the injectors a few months ago: #1 405, #2 395, #3 375, #4 375, #5 405, #6 375.

I then did a "wet" compression test; I squirted automatic transmission fluid into each of the cylinders and rechecked. The compression went from #1 405 to 420, #2 395 to 410, #3 375 to 405, #4 375 to 415, #5 405 to 415, and #6 375 to 395.

Mxfrank · #12 01-08-2015, 10:01 AM

Your next move should be to have the injectors pop tested. It's likely that there's at least one leaky injector, and there seems to be enough leakage through the rings to account for fuel in the crankcase. I think this problem, whatever it is, has been going on for a long time.

If the injectors are fine, drain the sump, put everything back in place and try using the FSM procedure for bleeding (not cracking lines or wedging levers). Other things that could cause this are bad lifters or a problem with cam timing. Oil in the manifolds can be accounted for, either being forced out of the cylinders while cranking, or sucked in via the turbo while running (because the sump is overfilled).

Stretch · #13 01-08-2015, 10:13 AM

Quote:

Originally Posted by Mxfrank

Your next move should be to have the injectors pop tested. It's likely that there's at least one leaky injector, and there seems to be enough leakage through the rings to account for fuel in the crankcase. I think this problem, whatever it is, has been going on for a long time.

...

Agreed - this seems the most logical way forward

vstech · #14 01-08-2015, 09:48 AM

No way you filled the crankcase to the brim with 1/2 a can of diesel purge... drain and inspect the fluid.

Onetoomany · #15 01-08-2015, 10:05 AM

Your injectors or injection pump isn't working correctly. You are either peeing fuel into a cylinder, or the poppet assembly is shot.

Injector re-furb isn't hard, just tedious. If you are in PHX, there aren't many shops that do them, but I believe European Auto Salon on 7th street does the older diesels. I spoke with the owner a few weeks ago about mine and he was very helpful over the phone.

If you need an IP, check with the Benz store in atlanta: Benz Store | Mercedes Benz Parts and Accesories | Buford Hwy Chamblee Georgia - Home, he does good used parts, and is reasonable on price. Ask for Ken or Clay. I have a used unit from him in my 95 diesel, and it runs beautifully.

Sounds like you dodged a bullet with the hydro-lock, I'd do a compression test as it sits to make sure you are good, then proceed with injector/pump.