I have a 1977 300D Engine # 617912-12-008247. When I turn on the
ignition the gloplug light stays on only about 2 -3 seconds and goes
out. In the warmer weather and when the car has been running recently
there seems to be no problem. I was told that it might be the sensor on
the front left hand side of the block. I have tried to find a parts
manual expanded view on the web.
1. Might this be the cause of my problem? if so how do I test it? how
much for a replacement part? new? used?

2. Where might I get a parts manual? how much?

I'm doing this for my Dad who is 81, any help would be greatly
appreciated.

Carl

Carl,

There is a CD available from Mercedesshop which will help.

But, the basics are:

Take a voltmeter and check to see if you are getting voltage to the glow plugs on the engine. With the engine cold, connect the voltmeter to ground and to the rear glow plug. Turn on the key and see if you are getting voltage to the plug. If you are getting voltage, but for a very short time, it could be the relay under the dash, or the sensor. There are two on the motor, the rear one is for the temperature guage, the front one is the glow plug sensor.

If you don't get voltage, follow the wire from the rear glow plug up to a plastic fuse box on the firewall behind the engine. There is a 50 Amp bar fuse in this box. If it is bad you will see it seperated.

I'm sure that Mercedesshop can supply you whatever you need.

Good Luck,
Larry