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1987 300TD Question

2K views 5 replies 4 participants last post by  Fritz-Karl 
#1 ·
Hi Folks,

I am looking for some advice on a 1987 300TD that is for sale in my area.
The ad indicates the following issue with the injection pump:

The only significant mechanical issue is the injector pump has a slow leak. Park on a decline, with nose down, and it starts right up. The injectors do not leak.

Any suggestions on how to determine if IP needs to be rebuilt or if an air leak is the culprit?

Thanks,

-Kevin
 
#2 ·
These injection pumps are quite hardy and can often last the life of the engine. My guess is that there are air leaks within the fuel system. Two possible culprits could be the fuel return check valve (on the back of the pump), or the fuel lift pump (on the side of the IP). If you do buy the car, I would plan on a complete overhaul of the fuel system, including all new lines, filters/screens and crush washers. Good luck with your decision. These are wonderful cars when properly sorted.
 
#3 · (Edited)
Hi! Like Zeitgeist wrote: it's air in the system. Most likely is it getting in at the pressure valves (6 in your case) because of damaged seals. I only have a german drawing:


You have to remove the intake and the injection lines. Than you can get out the valves and replace the seals. You will need a spezial tool to take the valves off. I have no idea what its called in English but its this one: click
If you know what you are doing its done in about 4 hours. The seals are cheap but the tool is about 50$ here.
A (German :D) manual (with pictures - yeeey) can be found here: click

I hope I could help, Cheers Fritz

Edit: found the numbers of the tool: It's Hazet 4556 or at your Mercedes-Dealer: 617589010900
 
#4 ·
That is exactly what mine was doing: park nose down was no problem; park nose up problem. I renewed the delivery valve o-rings and seals and haven't had any problems since.
 
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