Diesel Fuel in Engine Oil - Page 2 - PeachParts Mercedes-Benz Forum

TMAllison · #16 05-17-2009, 10:36 PM

Quote:

Originally Posted by Jeremy5848

My vote is for the lift pump. A seal failure could allow fuel to enter the crankcase but with everything else good, the engine would run well, as the OP reports.

x2, or x3, whichever it is.

Although, I would like to hear more about the failed DV job that was performed as NHDoc suggested previously.

bigblockchev · #17 05-17-2009, 10:55 PM

Is this a turbo or non turbo engine? just curious. I do not believe that fuel in the oil will cause a runaway engine. I believe that this is more of a risk if the rings are really worn then the engine may start to consume it's own lube oil & runaway. That is what I remember about all the runaway engine stories that I have read. I may be wrong about this but I am sure someone with more knowledge will pipe up. If there is serious amounts of fuel in the oil it will reduce the lubricity of the oil & may cause excessive wear on various engine components. Cheers Dan

Brian Carlton · #18 05-17-2009, 11:00 PM

Quote:

Originally Posted by bigblockchev

Is this a turbo or non turbo engine? just curious. I do not believe that fuel in the oil will cause a runaway engine. I believe that this is more of a risk if the rings are really worn then the engine may start to consume it's own lube oil & runaway. That is what I remember about all the runaway engine stories that I have read. I may be wrong about this but I am sure someone with more knowledge will pipe up. If there is serious amounts of fuel in the oil it will reduce the lubricity of the oil & may cause excessive wear on various engine components. Cheers Dan

Yep...........he's confused by another thread where an oil leak at the turbo allowed oil into the cylinders...........and a runaway was possible.

I don't see any scenario that will cause a runaway with diluted lube oil, provided that it's not leaking to the cylinders in some fashion.

godowning · #19 05-17-2009, 11:28 PM

It is a turbo. It's a 1991 300D 2.5 Turbo.

The problem I had was with the delivery valve o-ring replacement. In removing the old washer I accidently pulled and moved one of the delivery valves. But I was pretty confident that I was able to get it seated properly. But just to be sure I did the job a second time. I made sure to follw the proper torque procedure. I haven't heard anyone opine that even if I didn't get the delivery valve seated after both tries, that that could cause the diesel in oil problem I am experiencing.

I have found a lift pump repair kit for my IP. Should I give that a try before replacing the entire injection pump?

Brian Carlton · #20 05-17-2009, 11:32 PM

Quote:

Originally Posted by godowning

I have found a lift pump repair kit for my IP. Should I give that a try before replacing the entire injection pump?

Without the ability to positively diagnose the problem, the decision is moot. One costs $40........the other costs $200 (used) up to $800. (rebuilt).

godowning · #21 05-17-2009, 11:46 PM

The cost I am seeing for a new Lift/Primer Pump kit is $150-180. What am I missing?

TMAllison · #22 05-18-2009, 12:35 AM

Quote:

Originally Posted by godowning

The cost I am seeing for a new Lift/Primer Pump kit is $150-180. What am I missing?

Lift rebuild kit vs. used or rebuilt IP....... Do the lift pump first.

You want the lift pump rebuild parts kit 0000902650 assuming the detail previously provided is indeed your engine.

Jeremy5848 · #23 05-18-2009, 01:20 AM

I assume you can remove the lift pump with the IP still on the engine?

whunter · #24 05-18-2009, 02:33 AM

Quote:

Originally Posted by godowning

Hi, This involves my 1991 300 D 2.5 with 290k miles. I was hoping to get some opinions on what might cause a significant amount of diesel fuel to get into the engine oil. It amounts to about 1 quart of diesel in about 100 miles. Car otherwise runs well. I have changed both fuel filters and installed rebuilt injectors since the problem started. Car runs better with the new injectors, but no change to the diesel in oil problem. I have changed the oil and filter 3 times in the last 200 miles while trying to figure this out. My gut and other advice tell me it has to be an injection pump issue, but can anyone think of any other way to get that much fuel in the oil? Other work done to the car in the last 1,000 miles includes new timing chain and rails and new head gasket. Thanks in advance!

This issue is called making oil, older diesel mechanics are very familiar with it.

The lift pump is leaking into the crankcase...

It is a runaway waiting to happen, it would be an oil aspiration engine runaway.

Run away diesel, why does it happen?
Run away diesel, why does it happen?

Here is the repair kit.
OM601, 602, 603 Lift pump Repair kit

Have a great day..

godowning · #25 05-18-2009, 09:44 AM

Thanks for everyone's help. i have ordered the Lift Pump repair kit and will reply back with the hopefully positive results. Thanks!

JonL · #26 05-18-2009, 10:53 AM

Quote:

Originally Posted by ForcedInduction

It would only leak back into the fuel chamber that surrounds and feeds the plungers.

Ah, yes... of course you are right. It would have to be leaking at the base of the barrel, at the bottom of that fuel chamber.

NY300SD · #27 05-18-2009, 03:52 PM

This will cause a runaway engine. This happend a few times to a friend with a '95 E300 that had the same symptoms. Luckily these incedents where brief while climbing hills on the highway. I don't remember what caused his oil contamination in the first place.

#28 05-18-2009, 09:41 PM

Quote:

Originally Posted by JonL

Ah, yes... of course you are right. It would have to be leaking at the base of the barrel, at the bottom of that fuel chamber.

Which is very possible if somebody has water or gasoline contaminated fuel or tries to use jet fuel without adding lubrication. The clearance tolerances are extremely tight so fuel "blowby" is usually next to nothing. Extreme wear from bad/wrong fuel will wear the plungers just like using bad/contaminated engine oil will wear out the cylinders.

Diesel911 · #29 05-19-2009, 12:19 AM

Quote:

Originally Posted by Diesel911

Ways to spot Fuel Contamination in the Crankcase Oil:
If the Crankcase Oil smells like Diesel Fuel and the Oil Level keeps rising above the amount of Engine Oil added.
I have never had the newer Fuel Injection Pumps apart but these 2 items in the past used to cause leaks on Bosch and other types of Inline Fuel Injection Pumps with similar operating parts.
Worn Fuel Injection Pump Elements/Plungers and Barrels (Item #23 at the below parts site, you have 1 per cylinder). These are the parts that create the hight pressure for fue injection. I have read that WVO/SVO use can wear them out unless the Fuel is prepared carefully. If only Diesel Fuel is being used it can be a fuel filter or fuel contmination problem causing the wear of sometimes the IP is just plain worn out from long use.
If the Lift/Fuel Supply Pump Seals on the drive end of the pump (driven by the Fuel Injection Pump Camshaft) are no good Fuel pressurized in the Supply Pump can leak out of the seal.
The Lift Pump seals appear to be items #258 and #261 in below pic at the other site (I have not had one apart so I do not know exactly what seal is what).

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=124130&M=603%2E912&GA=722%2E415&GM=717%2E430&CT=M&cat=503&SID=07&SGR=045&SGN=01

I have also seen rare occasions when item #23 the Element/Plunger and Barrel assemblie; the Barrel portion is not seating well in the Fuel Injection pump Housing. There is no seal in this area. It seals Steel Barrel to Aluminum Fuel Injection Pump Housing metal to metal.

A source of the above problem could be if some one has change the Delivery Valve O-rings and managed to pull one of the Elements up a little. This could allow debre to get inbetween the sealing surfaces and interfere with the meta to metal contact.

The other stuff is farfetched; like loose Barrel,a split Barrel or rust erosion inside of the IP housing.

Below is a cross section of an IP housing (not a Bosch but similar). I tried to draw a red line to show that area that could leak if the Barrel was pulled up during a O-ring change and something got between the Barrel/Element Lip and the IP housing. In this area there is no seal; it is a metal to metal fit.

A way to test for this would be to remove the IP side cover and pressurize the IP housing up to the allowable limit in the FSM and see if you can see any leaks inside of the IP.

godowning · #30 05-19-2009, 08:28 PM

Diesel911

If what you described happened, could that alone cause oil and fuel to mix?

Thanks!