Cold start problems

[Iain]

I have a 1994 GMC with a 6.5 TD. Recently the truck has ben starting fine. I installed a manual glow plug timer (dash mounted button) to increase the length of time the glow plugs are on. After I installed it, the truck was hard starting cold. Just to satisfy my curiousity, I switched back to the factory controller and to my dismay, the truck started worse. There is power to the glow plugs as I have tested 4 of the 8 wires for voltage.

The glow plugs are AC 60G's. Is it possible that with the longer time used on the manual system that it could have killed any of the glow plugs that were weak? I haven't tested all the glow plugs yet, but that seems to be my only option.

[BobND]

I have a 1984 Sub running 60G's. I added a resistor (don't remember the value offhand, but have it written down in my notes) in the feedback lead to the controller to extend the glow time. It starts wonderfully, warm or cold.

Even though the 60G's are supposed to be so tolerant of the extended glow time, I have had three fail recently. They are about a year old. They have simply failed, they have not "swelled", broken, or "bubbled", so I can't guess if it's due to the longer glow time, or just defective GP's.

So I would say it is a definite possibility you have a bad GP or two, even if they're 60G's.

The 60G's I have are German made. Later ones I've bought are Japanese made (all genuine AC Delco).
I wonder if the Japanese units will be better?

A diesel shop guy I know claims he has seen some "made in Italy" 60G's. I guess GM just can't decide what they want to buy and put in 60G boxes!

To test the GP's, I use an old mechanic's ammeter made by Allen. I disconnect all the GP's, connect the (+) lead of the ammeter to the (+) battery post, then touch the ammeter's (-) lead to the GP's, one at a time, and note current draw (if any).

On the other hand, I have a 1994 6.5 TD that has all 8 of the original (dreaded) 9G's, and they're still working. I probably should change them, but it's always started so well I hate to mess with a good thing!

[Iain]

Thanks, you were right. I checked the glow plugs and had 4 burnt out. I replaced those and will try again in the morning as it is supposed to be a bit colder tonight (-12 Celsius).

[Hye]

Ditto on glow plugs. In my '94 they were all OK when I replaced the cracked heads @ 280K. IIABDFI!

[Iain]

Well the truck started like a top this morning! I learned a lesson about glow plugs, if it won't start, check them first. Thanks for the help guys!