[dksob81]

I am a mechanic not diesel though. My boss has a tow truck whcih has developed a problem since winter started. On cold starts it runs rough and rattles very bad after allowing it to idle for 15 minutes or so it will smooth out and run good. if it is plugged in it will run good as well. But right now it is 70 degrees out and shouldn't need plugged in, even in the winter the truck is kept in the shop at night (where it is kept around 65 degrees).

I have tested the resistance of all the glow plugs all read around .4 ohms when cold, there was one that read very high but I replaced it and still did not help. What could be the problem, like I said I am mechanic but do not know much about diesels. /ubbthreads/images/graemlins/shrug.gif

 

[Mr_Roboto]

First thing go through and replace ALL of the glow plugs. Use Motorcraft brand, they will be marked "Beru" on the plug. They are available at Autozone. Do not use other brands.

The performance of glow plugs degrades with age even if they are still "OK".

This may or may not fix the problem but we need to start with known good glow plugs to be able to diagnose the problem further.