So is my IP done or what? - PeachParts Mercedes-Benz Forum

Astroman · #1 05-05-2007, 08:39 PM

1981 300SD 290K miles. Over the last several months I've noticed a decrease in power, not major but noticeable. Did a valve adjustment, wastegate adjustment, checked timing and chain stretch, ALDA etc. Nothing has really brought it back. Starting has been more difficult and idle worsening. I actually removed the ALDA all together, and can't make black smoke even if I try. Today I figure I'm due for a diesel purge so I go all out. Drain the tank, check the screen (spotless) new filters, the works. I go ahead and do a purge then fill the tank with #2 and go for a ride. Now the car won't idle at all. Below 800rpm it just shuts off. Very difficult to start. So I run a few more errands, and it strands me for the first time in years. Not a bump or a chug or anything. All the lines have been bled, all the usual tricks done. It will tow start, but won't keep running. Next I swap out the injectors with a spare set and finally get it running. Come to find out the local station has had a bout with water contamination (though they'll admit to nothing). Could my injection pump just be worn out and tired, compounded with a slug of water in the fuel? What are the symptoms of a worn or worn-out IP? I was just about to do some adjustment on the full load, but maybe a fresh pump is in order. I did notice while changing the injectors, that while cranking without the injector lines the fuel out of ports 1,2 and 3 sort of just blurped out, while 4 and 5 really shot up. What's your .02?

TMAllison · #2 05-05-2007, 08:46 PM

You mentioned checking a lot of things, but not compression. I'd check that before trashing the IP too quickly.

Astroman · #3 05-05-2007, 09:17 PM

yes, I know the compression is sub-par. I question the IP because it seems like it's just not providing the fuel. I noticed a moment ago that to get it to start, I have to hold my foot on the floor and crank away. Without holding the pedal down, it won't even pop.

Astroman · #4 05-06-2007, 01:29 AM

Well, the car now runs like nothing ever happened. What appeared to have the most effect was backing out the rack damper bolt. If it was so tight before I don't know how I drove it around all this time, but whatever. The injectors I replaced also seemed to be full of black goo, so my purge might have really sent some junk through the system. I'll have them checked and see what the injection shop thinks.