Strange Observation - PeachParts Mercedes-Benz Forum

gersti · #1 10-20-2003, 10:44 PM

I just changed out my fuel filter on my '96 300D because I suspected it as being the culprit of my non-starting engine when I made a strange observation... I expected it to be full of diesel but it was almost empty when I removed it (and I did not spill any). The tank is about 2/3 full and the car was running fine when I parked it.

Now here is the kicker... I parked it at an incline overnight (say maybe 15 degrees) and that's where the problems started. I've only had the car for 7 days now and it's always been parked on the level. 2 days ago I parked it on the inclined driveway and the next day had a hard time starting it. After another night on the incline it wouldn't start at all the next morning.

Is is possible for the fuel to flow back into the tank if the engine is at a greater elevation than the tank for an extended period of time???

kerry · #2 10-20-2003, 11:01 PM

I would think it is possible if air can leak into the system somehow.

Ken300D · #3 10-20-2003, 11:04 PM

Perhaps you can park it nose down and look for diesel leaks.

Ken300D

gersti · #4 10-21-2003, 08:36 AM

OK, so now that the fuel filter is in and the battery is full I'm going to try starting the engine tonight. Do I need to prime the fuel system in any way?

What about re-installing the battery after I removed it for charging? Anything I need to look out for??

Thanks for all the help so far.

Gilly · #5 10-21-2003, 10:21 AM

Did you also replace the prefilter, and if so did you install the O-ring onto the prefilter?

Gilly

PS it will self-prime, but to avoid long cranking times, it's best to fill the filter will fuel

gersti · #6 10-21-2003, 10:24 AM

Yes, I did replace the prefilter (and the o-ring). I did NOT fill the filter fith fuel - I guess I better do that. Gotta get some diesel in a can then.

Thanks for the info on the self-priming.

Rick Miley · #7 10-21-2003, 10:25 AM

You should have filled the fuel filter with diesel fuel or diesel purge before installing it. The OM606 doesn't have a hand pump for priming like the older engines did. The system is self priming, but you will have to crank it for a very long time to fill up that filter.

#8 10-21-2003, 10:39 AM

Just going on recycled tips here, but I've heard that by prefilling the filter one can get unfiltered crud directly to the I.P., so be sure the fuel and the filter housing are very clean.

jcyuhn · #9 10-21-2003, 10:43 AM

This engine uses o-rings to seal the fuel lines. These o-rings are a common failure point. They either leak fuel when the engine is running, or admit air into the fuel system - sometimes both. Your hard start/non-start is probably air in the system.

When you get the car running again, look at the clear lines to/from the fuel filter. You should see; well, nothing. Lots of little bubbles running around in the lines indicates an air leak.

- Jim

kerry · #10 10-21-2003, 12:11 PM

I've just filled the filter with ATF. I don't know if it is good for your particular engine. You could also fill it with diesel purge.

gersti · #11 10-21-2003, 12:23 PM

I haven't actually started the engine yet so I can still fill the filter with fuel or diesel purge before I start cranking. Sounds like the thing to do... I'll see if I can get some diesel purge at a local truck stop today.

Gilly · #12 10-21-2003, 01:02 PM

Sure, you can take it off and fill it. I've used the ATF also and seems to work OK, I've heard it's good for the injectors, and it start and run just fine on the ATF.

Gilly