My truck is hard to start when cold. I checked the glow plug and they all semm ok to me. Th relay make a loud cliking noise when energized that las for 15 to 20sec. Voltage for the glow plug seem to alternate a lot (No analogic meter). Since the glow plug have to be energized with aleast 10 volts to warm up i think that my relay should be change. But since i dont know much about diesel engine i like if someone could confirm this replacement or should i check somethig else ???. Thanks

 

How did you check the glow plugs?

How do you know the voltage is varying if you don't have a meter?

What year of truck is this?


Brian

 

I check the voltage with a digital meter. Hard to see voltage variation with a digital. Better use a analogic one. The truck is a e350 1989 with a 7.3 diesel engine. Voltage at glow plug is check with positive probe on glow plug connector and negative groung on body, transmission or else.

 

Again how did you check the glow plugs themselves? It sounds like your controller is working fine, if the relay in it was bad you would have no voltage to the glow plugs.

Brian

 

I think the relay go on, and off, and on and off etc.. for 20 sec. It give current to glow plug to warn up a bit but not enough. That would explain the voltage variation and the fact that it takes may try before the engine start.

 

[updated:LAST EDITED ON 25-Jul-02 AT 00:35 AM (EST)]If the controller is cycling on-off you probaly have some bad glow-plugs. I have been told by some Ford technicians that just one bad plug can lower the temp. on the rest of them by 600 degrees F. Plus the controller will sense the shortage of current draw and reduce the cycle time as not to burn the others up.

The best way to test them is pull all of them out then, one at a time take a jumper cable clamp it to the body (ground) of the glow-plug connct it to the negative side of the battery then touch the terminal of the glow-plug to the positive side of the battery if in 10 sec. it doesn't glow red it is bad, when it glows immediatley disconnect it as there is much more current running to it then there is when all 8 are connected.

The controller should stay on for 20-30secs. cont. when you turn the key on.


Brian

 

If i unplug both gray cable (Used to power up the glow plugs) then the relay if working good should stop his clicking behavior and stay energized for the 10 secondes. If so, i can reconnect the glow plug one by one and try the relay each time and find out the one that would drain too much current no ????

 

No, the less of a load the less time the controller will keep the relay on. Only when all eight glow-plugs are connected and in working order will the controller stay on for 20-30 secs. without turning off.


Brian

 

all Glow plugs were changed this evening. You were right the relay work correctly. The truck now start after 10 to 20 secondes of waiting time. Thanks a lot. ROger

 

no problem glad to help you. I have replaced many glow-plugs in my 91 dsl.

Brian