Back to the basics then :
When my '78 300CD had intermittent low power it turned out that the primer hand pump was dying of old age, I replaced it and !VIOLA! .
Any leak out no matter how small is also a direct air leak back in .
The black slimy crud you encountered in the filter housing is old fungus ~ it takes some time to get rid of all of it, I'd suggest dumping a full half gallon of Starton into a full tank and suffer the crappy driving until the tank is empty, you'll prolly have to replace or blow out the clear plastic intake screen a few times as the Startron goes to work .
Conversely most truck stops carry a product called " Diesel 911" that's also very good at cleaning if not as good as the Starton or K100 .
Interestingly I found the K100 stuff to work even better than Startron .
Mostly you have to have patience and diligence once it's bad .
So many good Mercedes get junked because of this issue .
Glad I persevered with my '84 300CD as it's a stormer again for now anyway .
-Nate
Mark wrote :
I have a ready flow from the fuel tank. While primer pump leaks while in operation, it fills the filter with a few strokes and the clear filter gushes nicely. I thread it back down and no more leak. I found a small leak at the rear injector. I cut off the return hose and reinstalled it and now that is dry.
Yesterday, I continued my quest for fuel restrictions downstream from the pre-pump. I dismantled the filter housing and cleaned all of the banjo fittings. The only thing that was at all awry was the tiny bleed hole from the top of the filter area to the return was partially blocked and I cleaned it with a piece of copper wire. The insides of everything is black. I added another bottle of cleaner.
I put it back together and with a little extra cranking and wobbling around, the engine picked up all four cylinders and idled nicely.
I was very disappointed when I tried to drive it. It had less power than ever. I could barely get it up to 40 mph on a level. The strange thing about this lack of power is that the next time I run it, it will be normal, with beaucoup pep. I have never had it lose power once it is running right, but once in a while it will gradually give me my power back. I wonder if the fuel flow governor is sticking.
The hard starting is very predictable. The glow plug relay seems to be working fine now as the light comes on every time. Perhaps the ignition switch was intermittent from lack of use. But I crank for 10 seconds, 10 seconds, then the third time, it stumble starts. It's as if the injection pump has trouble reestablishing flow to the injectors.
I think this car had years of neglect or it sat for a VERY long time. A shame, because the body and interior are in such good condition. Once I get past this problem, it will be a great car.
Excellent advice. Thank you. I am now on only the third tank of fuel since getting the car and the second using an additive. I am trying Lucas fuel treatment right now, but I found K1oo near me and I will grab a few bottles.
-- Mark L. Bardenwerper, Sr. Technology...responsibly, thoughtfully
