Hello I am new owner of '85 300 D, turbo. The dash glow plug light is not working but we have checked and recently replaced a grounded plug thinking that would get the instrument to start working correctly. How do I test to see if the glow plugs are warming up? Been getting cooler here lately and the car was a little harder to start this weekend. Worried that glow plugs are not running when supposed to. Have not opened dash to see if light is burned out.....have not figured that procedure out yet. The ignition switch is a little sloppy, as you have to turn the key just so to get the a/c heater to come on. Related?

 

well i think there is a way to test the resittance, but the fun way is to wait till the engine is cold and turn your key to on, not starting the car then just go touch them and see if they are hot.

 

Welcome to the forum. We've had lots of discussion here about this very issue. If you do a Search I think you may be surprised to find the volume of information (and probably the solution, too) related to your question about glowplugs.

 

Glow plug relay was OK. 2 plugs were bad. (I cheated, had to take it to the dealer for dianostic, but did the repair at home) Since the plugs are apparently working in series, if one is bad then the rest after it don't work. Fun replacing in confined space. Craftsman ratcheting box end wrench works great for the position. Dash indicator light now working for glow plug.

 

How long did it take you? I've got to do mine sometime very soon.

 

All five glow plugs can be replaced in a little over an hour with modest tools. The one closest to the firewall behind the oil filter will take the majority of the time. [>:]
Removing the injection lines first is almost a necessity.

 

Oh, mine is an '84 300D.