I have a problem with my '85 300/240D. I have a 300D with a 240D engine and 4 spd manual transmission in it. The problem I have is that when I turn the key off, the engine keeps running. Short of popping the hood and hitting the kill switch, the only way I can shut it off is to pop the clutch with one foot on the brake. I encountered this problem a year or so ago with my '80 300D, and the problem turned out to be the vacuum valve on the ignition switch, behind the dash. I tore the instrument cluster out of it on Sunday and proceeded to replace this part when I noticed oil on the ignition switch and around the vacuum lines on the valve. I replaced the part and this did not solve the problem. Now I have no idea where to look. I figured that the vacuum pump is working fine since my door locks are still working properly and all other systems on the car work also. Any help here would be greatly appreciated.

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Mike

'80 300D
'84 300D
'85 300D
'87 300D

TXBill,
I have checked just about evey vacuum line and fitting I can find. I have a good vacuum pump and gauge, but this one is very elusive...it is kicking my hindside. I have not tried the shut off on the injector pump yet. I guess that will be my next stop. What is hte best way to test that thing?, or do you take the shotgun approach to troubleshooting and just replace it?

Thanks for the quick reply, my wife is really wanting me to get this fixed soon...she is tired of popping the clutch to stop the engine.

Mike

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Mike

'80 300D
'84 300D
'85 300D
'87 300D

TXBILL,
Just read the edit to your post. How hard is it to rebuild the vacuum pump. I am a pretty handy guy and am willing to tackle most projects, but don't want to get in over my head.

Mike

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Mike

'80 300D
'84 300D
'85 300D
'87 300D

sublettm,

I encountered this exact problem a few years ago on my 240D and the diaphragm you have that has failed is in the mechanism that is shutting the fuel off at the injection pump, I believe. When this happens the vacuum line to the starter switch draws oil from the injection pump and into the switch mechanism. On my car it leaked a lot of black oil all over the panel above your legs, and then ran down the side of the center console, making a black stain in my palomino covering next to the driver's right leg. Nasty.

I do not recall the new part being particularly expensive, or cheap for that matter. I had the dealer do the job as I was unsure of how much of the vacuum system was shot. Turned out it was only the mechanism on the fuel injection pump. I do not think there are any other places where engine oil can get into the starter switch though.

Hope this helps, Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)