Hi. Just joining the forum. Maybe you can help me out with a little problem. My mechanic is not certain what to do... I am not a troubleshooter - just a driver. Thanks.

Car: E300TD 167,000 miles

Problem: Late fall cool morning power loss. 40F to 50F outside temperature at start. The car starts fine (no issues at all). Idle is fine. After driving about 1/4 mile the car burns very rich (exhaust cloud) and loses power almost cutting out entirely on a slight incline. Engine temperature is 40 to 60 during the problem. At 80, after 4 or 5 miles the car runs perfectly fine as expected.

Condition: The car is maintained to factory suggested A/B maintenance schedule by non-MB mechanic familiar with MB cars. No active codes showing any issues.

What would you suggest? It is approaching winter in the NE and I am getting concerned (worried).

 

Thanks for taking the time to offer some advice. Thought I'd get more information before responding.

I checked the left side electrical connections with my mechanic. We had considered replacing the glow plug relay module when the glow plugs were replaced a little over a year ago. It wasn't done and still tests out okay. No new lead to the problem and solution found here. Vacuumed out the air box and filter (getting new filter today).

I have started taking notes as to exactly what I do in the morning and how the car responds. By doing this I've notice a inconsistent shifting behavior -- the car appears to be uncertain as to what gear to be in. It hard shifts even slightly, but noticeably. So I pull over. White smoke, engine responds well in neutral and loss of power when in gear. Same outside conditions (38-50 degrees F with engine temp between 55 and 75 degrees C).

Today I ran the car by manually shifting through 1, 2, 3 and then 4 by RPM and not automatic (keeping revs higher) to not lug the engine at low RPM -- NO ISSUES! Outside air at 38 F, engine at 60 C. Car ran as expected with not white smoke, no power loss. This appears consistent with the experience that after warm up and the first run of the day it runs fine for the rest of the day.

I am going to test the transmission theory this week. Any thoughts?

 

Okay so here is the answer to the problem.

I reached the pinnacle of frustration when my car wouldn't start on a cold morning (distracting fact) after sitting for two days without running. This is the real clue to the issue. The car would lose the pressure in the fuel system feed while sitting due to a combination of leaks in the system. Since there were potentially so many it is hard to say if one only was the driving factor or if all combined caused the problem - each contributing their part. $1400 dollars later I had replaced the shutoff valve (housing leaking), the plastic line to and from the valve, the return line running to the fuel filter assembly, the o-rings for the injectors and the neoprene lines inside the engine compartment running from the steel delivery lines where they enter the compartment (the rear neoprene lines were okay). Included in the price also was the pre-filter and the main fuel filter although this was just for maintenance since they were due.

What caused the "first of the day" starting and poor, loss of power, running condition was AIR IN THE FUEL SYSTEM. Air leaks were caused by cracked (although not leaking) neoprene lines now permeable to air, leaking o-rings and distribution lines possibly due to age (seal compression set and gaps) and maybe due to low sulfur (post 1999 design condition) fuel makeup causing accelerated and premature failure. Sitting for two days completely air-bound the system and the car wouldn't start and had to be towed to the garage.

Anyways, it now starts instantly and runs great! $1400 later. Mileage is approximately 170,000 - looks and performs great. Going for another 170k.