Hey all - I'm working on my girlfriend's 1976 300D. It overheated a short while ago, and we havn't been able to get it to start & stay running since then. I've tinkered with it to the point where it's now starting again, but I have to keep the accelerator all the way open to get it to start. It will run briefly, as long as I keep the accelerator at WOT, but if I bring it down at all the engine winds down and stops pretty rapidly.

Any feedback/ ideas on what I should be checking? I havn't done a compression test yet, but I did go out and pick up the tester to do it (havn't had quite enough time to do the test yet though). Since the engine still starts and seems to run smooth for the periods I'm able to keep it running, I wasn't sure if compression could be a culprit or not.

Thanks in advance for any help y'all can give!

Maybe a bad lift pump or an air leak into the fuel system. Check to see how much the lift pump is pumping when you crank it and try running it on an alternate fuel source in the engine compartment.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Does the IP have enough oil in it?

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Engine and IP share a common oil supply.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

It should - that was one of my first checks. Turned the engine over to get the oil moving into the IP, then checked oil level in the engine sump. Havn't gone so far as to pull the feed/return lines off the IP to check the oil supply in it yet, though.

Your girlfriend drives a 76 300D? Dammit where do you find these girls..!!?

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Tomas, Sweden
1966 Mercedes Benz 230S with OM617.912, automatic. Disk brakes from W108
1983 Mercedes Benz 300TD grey, OM617.912 and 5-speed manual
1983 Mercedes Benz 300TD blue 7-seater, OM617.912 and 5-speed manual

She did, when it ran....
Broken down on the roadside :p

I'll go try running it off a second fuel source in a bit.. see if there's another leak. The overheating melted all the Viton lines I'd put in the injector return circuit, so it's possible I've got another weak spot that I missed when I just hunted through the fuel system.

even in a 115? i thought they were separate on mine, but mine's a 240.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

it is a fuel problem, it has a restriction somewhere filter, hose, filter screen in tank,see if it run out of a can of clean fuel. have seen these fuel line corrode to the point on restriction, if it will run on clean separate fuel out of a can then you need to start at the back Fuel tank and work you way forward until you find the problem you could take the line loose at the tank and at the front and blow compressed air and see what you get out of the line stick the line in a container and see wht you get out of it, trash in the tank filters it all happens with age..........let us know

I may be mistaken. I thought the 617 had a common oil supply even in the 115.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I think Kerry's right. From my FSM CD it shows that only early 4-cylinder engines (615, 616) have the "oel" cap for adding oil to the injection pump.

BTW did you find out what was causing the overheating? While I tend to agree with the fuel leak theory, are you sure the head gasket isn't blown?

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1976 240D "Katja"

The overheating was either an obstruction in the cooling system, or the water pump failed. The engine got hot enough to melt the Viton lines while the radiator was cool enough to touch. It is entirely possible I blew the HG, which I'm hoping wasn't the case. I'd like to try and get the car running well enough to limp home in stages (it's on the road about 25 miles away) before digging into repairs like the water pump - or, heavens forefend, the headgasket.

By the way, before I go disconnecting the fuel lines, where is the primer pump on these cars? I can't find anything that looks like a primer, and that was the first thing I went hunting for. I have a spare primer of the old IP from my '83 Frankenbenz (had to fix that a few months back) that I can plumb in, but it would be handy if there's one there already for when I switch back to car's fuel tank.

There is a cut off year when the IP needed to be filled w/oil via the red dip stick hole and getting oil from the engine. I do not remember which year thatwas though. It was in the 70's IIRC.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Even on the 617's? I know it was the case on the 616.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

That I do not remember...

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K