I just bought a 82 300d that was doa. It was explained to me that the car drove fine- perfectly- until one day going down the road- letting off the accelerator- the engine died. Hasn't restarted since. Previous owner replaced all the diesel in the tank and changed the fuel filter. Still nothing at all. Was told diesel was getting to the engine but not under alot of pressure (previous owner took injector line off).

So with this knowledge what would be your troubeshooting list starting point?


I am a MB newbie but been working on diesels (fords powerstroke) for years.

Please ,if you wouldn't mind, include any link or post info if a certain procedure is mentioned that may require a special procedure or something less then obvious.

Thanks so much!!

Tony

My 300D did that a couple of years ago. After having it towed to the shop, it turned out to be a crack in the plastic booster/primer pump. Apparently it let enough air into the fuel system to keep it from starting, even with lots of pumping.

Would you have evidence of diesel coming out of this part if it was cracked? Where is this part located exactly?

Thanks,
Tony

If its the old style with the white knurled knob down on the side of the ip, odd are its leaking...unscrew it and pump....if it leaks fuel out then its leaking air in.....

Get an upgraded one . They cost all of about $20......

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Hey Tony, all I can say and I don't know too much, but that is a wide open question. What I would suggest is a bit more diagnosis on your part. Is it getting fuel, is the fuel good, does it crank. It is hard for the experts who put much time and thought into many more pointed questions to start theorizing without more facts. Also, use the search feature at the top of this page. You will be amazed what you can come up with. It doesn't really take too much to make that 300 run - air, fuel, compression and luck will usually do it. What key feature is missing on your engine. Fuel delivery, (timing) is very important also. But if it stopped while running down the road, I suspect I would start with fuel filters.

__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Mine has left me dead twice. Once it was fuel filters. The other time it was out of fuel, even though the guage read above the R.

__________________
79 MB 280 SEL Euro 133k
77 MB 450SL 154k
05 Mustang GT Vert (3) 104k
12 TSX Wagon Tech (66k) (192k)
06 Subaru Outback base (135k) 164k
16 Acura MDX (109k) 111k
18 Silverado 2500 LTZ Midnight (212) 56k
97 Ford Ranger 163k
11 RAV4 154k
01 Escape 173k
04 Honda Pilot 292k
1967 Mustang (Resto Project)
1968 Mustang (Parts Bin)
00 Ford Ranger 124k

There should be three filters... any one could cause starvation....
one in tank, two in engine compartment....one inline, one big screw on....all should be replaced or cleaned before going further with other stuff unless leak can be shown to exist on the hand pump.

Other thing to check is the breather for the tank. If you here a hiss when taking the cap off the fuel tank you have a problem. That caused my benz to die. I could overcome it by forcing fuel into the lift pump and air back into the tank with the primer but after I fixed that problem, no more dying 300SD!

__________________
My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory

To answer your question, there is a hand priming pump on the left side of the engine, about half way back. It will either be a white handle that you have to unscrew and pump (old type), or a black plunger that you just push down to pump (new type). The old type pumps tend to leak and should be replaced.

This may be a dumb question, but did the PO and/or you make sure the fuel system was primed after replacing the filters? Before you do anything drastic, try pumping the priming pump about 30 times and try to start the car.

eBay: Mercedes Volvo VW Case Deere diesel hand primer $18 after shipping.

My pump leaks when hand pumped. So I figured: I'm pulling my engine and replacing old parts, why not.

For $18, it's peace of mind that your fuel system is airless.

Thanks so much for a place to start. I will check those filters again and check the primer also. I have been doing alot of research using the search feature and feel alot better about what things are under the hood and what they do. I also ordered the new primer just to be safe--thanks for the link.

Tony