Glow Plugs...

[dogan124]

If the glow plug light behaves un-normal then one or more of the glow plugs are dead. This is something I have learned by experience and advice.

Last week I had the plugs checked out (hard start) and found one dead, the glow plug light was just as normal though.

Then is it wright to say "an unusual behaivor of light indicate a failing plug but not a must for it"?

By the way the failing plug came out to be 11 V where as the service says it should have been 11.5 V. What should be the correct grade (w124 300d 1991)? What could it cause if not correct ?

Regards

Dogan

 

[jimmy]

To test the glow plugs you either have to take them out and test each one physically by connecting to a battery an see if they glow or test the resistance of each one, an open circuit would indicate a fault. Voltage at each plug will not tell you if they are working or not.

 

[dogan124]

To test the glow plugs you either have to take them out and test each one physically by connecting to a battery an see if they glow or test the resistance of each one, an open circuit would indicate a fault. Voltage at each plug will not tell you if they are working or not.

Jimmy,

11 V was not the voltage tested at the plug it was written on the body of the plug. On the new plug fitted it was 11.5 V.

thanks,

Dogan

 

[jimmy]

Ah, I see.

It should not matter too much, different glow plug manufacturers will have slightly different specifications. In theory a 11.5v plug will last slightly longer than a 11v one but not noticably. Glow plugs range in voltage from 5-6v to 14v. Somewhere around 12v will be fine. The lower voltage plugs use a ballast resistor in the circuit to lower the voltage.