Odd Glow Plug Problem

I have searched everything I can find to search but can't find an answer. Seems as though most have trouble with glow plugs not working. My problem is just the oposite. I can't get them to stop. At least not with a temperature under 200 F. This truck is new to me. 1984 C3500 6.2L 4 Speed w/ granny low. 4.56 rear. 49,000 miles. The mileage is one of the reasons I bought it. I have replaced the thermostat. Was 160. Now 180. I have replaced both batteries and alternator and 5 or 6 alternator belts. I think the alternator is lined up now. Seems I couldn't get it hot enough to stop the glowplugs from cycling. The glow plugs have an enormous drain on the batteries and alternator (78 amp.). I find that even in 10 degree temperatures at 3200 rpm's it takes at least 45 minutes to get the temp up enough to stop the glow plugs from cycling (pre 180 stat). Just put it in yesterday. Better now but still a problem. Can't seem to get the alternator belt to stop squeeling when the glow plugs continually fire up. Battery is loosing charge. Headlights getting dim. I thought by replacing all that I have the plugs would stop cycling after the engine warmed up. Additionally, the 20 amp guage fuse keeps blowing. Seems to happen after starting when I have had the block heater plugged in the night before. Cruise dosen't work. Was told the previous owner had it disconnected? Clutch seems to be stacking up after repeated use in town. Sounds like a lot of problems and my wife thinks I've bought a money pit but I really like the truck and would like to keep it. If I could determine the causes of these problems and fix them myself I could keep the costs down. Many on this board have helped me with other questions and I hope someone can help me with these.
Thanks
Frank

Frank, I replaced the early style glow plug controller and solenoid with the later ('85 up) system. That system works much better than the old controller. I used to have similar problems, and it cost me an alternator, several fusable links, etc. GM replaced the old controller which threads into the driver's side head with the new controller because it is a better design. I mounted mine just where the old solenoid goes, and did not even have to do much wiring. You will need the proper plug assembly for the new controller or you can make your own. Do a search on glow plug controllers on the site, and you should find some additional information.

Good luck,

Kevin.

Could it be a malfunction of the glow plug inhibit switch?It sounds like the opposite of what they are intended to do.I believe it is an`84-only component.

In the past I've run into the same problem. Usually it occured when the Alternator Belt broke or came off (this is how I could tell when my belt was broken or was worn). In every case the problem went away when I replaced the belt and got it tight....which is no small feat on the V belt setup with AC! My truck is an 83 so I think we have the same controller setup.

I recently converted my multi belt system to the single serpentine belt. I currently have the same problem but it seemed to occur right after I washed the motor on my truck. The relay is working fine so I suspect it is the sending unit on the motor. I am currently (when it is cold) lifting the hood when I start it...unplugging the connector to the solenoid after it starts...then closing the hood and going on my way. NOT a very elegant solution (especially at a funeral or "dress up" event!). At least this is not stressfull on the plugs and does not drain the battery. I just ordered an adjustable controller from Peninsular Diesel ($87). It lets you set the duration from the controller in the cab and only fires once.

$87. Sounds like I can take care of the old glow plug controller problem as well as any continuing problems that may occur with the new style GM controller. Thanks ALL for the advice!
Frank

The old style (82 to 84) glow plug controller was a bit of a mess and over complicated. It's supposed to have a signal from the alternator to let the controller know that the engine is running and to stop cycling the glow plugs. It's not that uncommon to have the controller fail in that respect and never shut the plugs off.

The old style controller is expensive and not very reliable, so upgrading to the newer GM controller or Peninsular controller is a good idea.

Casey