Blew engine last night - why, oh why? - Page 3 - PeachParts Mercedes-Benz Forum

whunter · #1 04-29-2011, 04:10 AM

Quote:

Originally Posted by luke4

I just drained somewhere in excess of 16 quarts of fluid out of the crankcase. I had a normal amount of oil in there before - the rest is fuel.

Prior to oil change, level was normal. Following change it was checked/normal too. I added the normal crankcase capacity (9 quarts I think it is) during the oil change. I drove it about 200 miles in total since the oil change. Injectors were rebuilt because the engine was noisy and I am/was thinking it was worn injector pinging. Not sure yet. 500 feet driven since injectors reinstalled.

Also just removed the lift pump off the IP. No obvious signs of leakage. I used lung pressure to see if there was any leakage past the shaft (on the side of pump that's in the IP) and there was no detectable leakage past the shaft passageway.

I thus far have been unable to get the lift pump apart to get a visual on the internal seal.

Any suggestions?

The only logical answer is a failed lift pump.

The total volume of fuel pumped into the crankcase exceeds any possible injection pump output.

As I recall injection pump volume is between 0.0x and 0.00X CC per cycle = this is why it takes seriously extended cranking when you totally run out of fuel..

scottmcphee · #2 04-29-2011, 08:42 AM

Your diesel tank is not venting air properly. The car was sitting in the sun for a couple weeks before the injector job, the tank was about 3/4 full at the time. While it was sitting there the tank would pressurize up and force diesel down both the return and supply lines to the IP. Diesel pushed by "something" in your IP and kept on going. Fuel filled the IP lube oil space and found its way through the front of the IP and spilled into the crankcase through the timing cover. It did this until the return line was exposed in the tank, at which point the fluid pressure was no longer sufficient to push into the IP.

Find the "something".

whunter · #3 04-29-2011, 02:37 PM

Quote:

Originally Posted by whunter

The only logical answer is a failed lift pump.

The total volume of fuel pumped into the crankcase exceeds any possible injection pump output.

As I recall injection pump volume is between 0.0x and 0.00X CC per cycle = this is why it takes seriously extended cranking when you totally run out of fuel..

The only other answer is the braided fuel bypass hose, from injector #1 to the fuel filter was stuck into the injector hole for weeks.

If the fuel tank vent valve is bad/plugged = This would cause an issue called breathing:
* Daily Heat expansion would flow diesel into cylinder #1.
* Nightly cooling would suck air back into the tank..
* A variation of 10° F (or more) between night and day is all that is needed, the wider the temperature difference = more fuel transfer...

Easy to test = remove the fuel cap and listen for pressure escaping..

mach0415 · #4 04-29-2011, 09:22 AM

Quote:

Originally Posted by luke4

I just drained somewhere in excess of 16 quarts of fluid out of the crankcase. I had a normal amount of oil in there before - the rest is fuel.

Prior to oil change, level was normal. Following change it was checked/normal too. I added the normal crankcase capacity (9 quarts I think it is) during the oil change. I drove it about 200 miles in total since the oil change. Injectors were rebuilt because the engine was noisy and I am/was thinking it was worn injector pinging. Not sure yet. 500 feet driven since injectors reinstalled.

Also just removed the lift pump off the IP. No obvious signs of leakage. I used lung pressure to see if there was any leakage past the shaft (on the side of pump that's in the IP) and there was no detectable leakage past the shaft passageway.

I thus far have been unable to get the lift pump apart to get a visual on the internal seal.

Any suggestions?

Yeah, lung pressure will not be enough to "pressurize" a seal enough to get it to leak, more than likely. Is there a way to test all the theories mentioned by using low pressure on the fuel cap (modify a cap to regulated low shop air pressure), like testing a cooling system? If so, perhaps there is a way to detect the leak at the lift pump. Though the lift pump is the only plausible culprit, I would hate to replace an unconfirmed suspect part and then actually have the engine grenade as a result of runaway, if it was something fluke-ish.

kerry · #5 04-28-2011, 11:04 PM

Is it possible that there's a leak internal to the IP?

funola · #6 04-28-2011, 11:22 PM

Quote:

Originally Posted by kerry

Is it possible that there's a leak internal to the IP?

Is there a path in the IP to the engine? I don't think fuel can get out through the IP drive, that leaves the lift pump. I can't see how an injector can dump that much fuel into the crancase in that short run time unless a nozzle pintle spring is missing and there's a hole in the piston.

kerry · #7 04-28-2011, 11:48 PM

Quote:

Originally Posted by funola

Is there a path in the IP to the engine? .

It's lubed with engine oil I think so there has to be a path between them. It's the only possibility that makes sense to meif the lift pump is ok.

funola · #8 04-28-2011, 11:54 PM

Quote:

Originally Posted by kerry

It's lubed with engine oil I think so there has to be a path between them. It's the only possibility that makes sense to meif the lift pump is ok.

IP engine oil lube line is an external banjo bolt black nylon line. Someone who rebuilds IP's will know if it is possible for fuel to spill into it.

Jeremy5848 · #9 04-29-2011, 12:48 AM

Quote:

Originally Posted by funola

IP engine oil lube line is an external banjo bolt black nylon line. Someone who rebuilds IP's will know if it is possible for fuel to spill into it.

AFAIK, the OM60x engines do not have an external oil supply line.

Jeremy

Jeremy5848 · #10 04-28-2011, 11:09 PM

Who rebuilt the injectors? I'd take 'em back, see if they left something important out of one or more. Engine may be OK.

luke4 · #11 04-28-2011, 11:26 PM

there's way too much fuel (8+ quarts) in the oil for it to be the injectors, as it ran with the rebuilt ones in for maybe 3 min. It's burning some of that fuel and I understand they're pretty low volume.

How would I check for a leak internal to the IP? (for the shade tree mechanic)

What about testing the lift pump by plugging one fitting and applying pressure (mity vac) to the other and seeing if it leaks?

barry123400 · #12 04-29-2011, 01:50 AM

Quote:

Originally Posted by luke4

there's way too much fuel (8+ quarts) in the oil for it to be the injectors, as it ran with the rebuilt ones in for maybe 3 min. It's burning some of that fuel and I understand they're pretty low volume.

How would I check for a leak internal to the IP? (for the shade tree mechanic)

What about testing the lift pump by plugging one fitting and applying pressure (mity vac) to the other and seeing if it leaks?

Clamp off or close the return line from the injection pump. You should not be able to pump with the primer pump. Oops this is a 603 yet some simular test may be made as it has no lift pump.

Perhaps closing off the supply line on the feed side and trying a gravity feed through the return line. It should take no fuel. Get the fuel feed high in the air if possible.

Also since this was not a previous existing condition until the injectors where installed. Perhaps someone left the springs out of them. You should test them quickly for pressure pop point.

Although it is hard to imagine so much fuel passing into the engine through this way in such short order. Logically those replacement injectors are suspect regardless of what is thought.

funola · #13 04-28-2011, 11:30 PM

Gotta be coming from the lift pump then. There's an o-ring on the pump shaft which blew out?

luke4 · #14 04-29-2011, 11:21 AM

Methinks mine theory in original post doth have merit. The car sat for several weeks in the warm sun while waiting for the rebuilt injectors.

Quote:

My guess is that after pulling the injectors, since the lines were over the top of the holes that they dribbled fuel into the cylinders, which then leaked past the rings into the crankcase. But to overfill the crankcase, that would have to be a LOT of fuel. Is it possible that the full gas tank when warm had positive pressure and pushed fuel through the IP and out the lines?

Guess I could test the theory by disconnecting the injector lines and applying pressure at the cap and see if they dribble.

Nonetheless, now that I have the lift pump off, how do I test it? Apply mity vac pressure to the outlet fitting (pressurized side) with the inlet plugged and see if leaks down (presumably out the shaft passageway)?

How many PSI do these lift pumps produce (so I don't overdo it and damage the pump)?

Zacharias · #15 04-29-2011, 11:53 AM

Quote:

Originally Posted by luke4

Methinks mine theory in original post doth have merit. The car sat for several weeks in the warm sun while waiting for the rebuilt injectors.

Guess I could test the theory by disconnecting the injector lines and applying pressure at the cap and see if they dribble.

Yes but at that volume of "drip down" you would have been able to smell it clearly from at least 20 feet away. I can't drive my car with even a small dribble sitting somewhere after changing filters.

And you would have seen evidence of the leakage when you returned to the car to install the injectors.

Plus I have serious trouble imagining enough drip down to fill the crankcase as you describe.

If diesel got in there, I'm liking the other theories much more.