1985 Mercedes Benz 300sd glow plug

  • 1985 MERCEDES BENZ 300SD
Engine problem
1985 Mercedes Benz 300sd Two Wheel Drive Automatic 274, 00 miles

Recently, I had to jump start my 300SD after some cold weather. I live on the CT shoreline and had to give it a shot of starting fluid to get it to start. I have been in the automotive business over 35 years and was a jet engine tech so I know my way around under the hood. Since starting it, the glow plug lamp on the dash does not always illuminate when turning on the ignition and starting has been a little problematic. I had a friend of mine look up the location of the glow plug relay on Alldata and after finding it, found one of the contacts pushed out. I thought that could be the problem, so I secured it, but am still having the same problem. Could you possibly advise me what to look for or check. Its a great car and I plan on having it repainted this spring, so I want to keep it mechanically good as well. Thank You
Do you
have the same problem?
Thursday, February 14th, 2008 AT 4:35 PM

1 Reply

Heres a couple of tips to help you solve your starting problem:
1. You will need a test light and another person
2. Disconnect each connector on all 5 glow plugs
3. Have the other person cycle the ignition switch to the on position, using the test light check to see if each connector to the glow plugs have continuity or 12 volts, if so replace glow plugs
4. If continuity is not found at either 1 of 5 glow plugs, check the 80 amp fuse in glow plug timer relay
5. If fuse is ok, replace timer relay
Hopefully this helps! Good Luck.
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Thursday, October 9th, 2008 AT 11:10 PM

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