CleviteKid
04-25-2004, 08:28
Back in 2000, More Power had an article on www.TheDieselPage.com (http://www.TheDieselPage.com) about the inner workings of the glow plug controllers for the 1985 - 1993 trucks. Based on that examination, I upgraded the thermo-mechanical nightmare system on my 1984 to the next generation of glow controller.
In his article, MP reported his analysis and tests of adding a 5 ohm resistor to the feed to pin "C" of the controller, which added 2 to 4 seconds of glow time. For use with the AC 60G glow plugs, which heat up slowly and don't reach the same peak temperature, this extra glow time can be beneficial.
Here in Miami I have not needed extra glow time, but ever mindful of our members in colder climates (almost all of you) I have looked into a refinement of that suggestion. I have added a Negative Temperature Coefficient (NTC) thermistor with a nominal value of 5 ohms at 25C (77F). The NTC part means at lower temperature the resistance is higher (longer glow time) and at higher temperature, the resistance is lower (shorter glow time). Before installing it for testing, I first measured the resistance at room temperature and saw 4.9 ohms on my Fluke. Then I put the thermistor between two ice cubes, and watched the resistance rise to 13.8 ohms. Finally, putting it in 180F water dropped the resistance to 1.9 ohms. Promising.
In the engine, at about 80F ambient, my initial glow time was increased from about 4 seconds to about 6 seconds. Now all I need to do is to find a drive-in freezer to test the low temperature effect :eek: .
The NTC thermistor I used was from Digi-Key, and is a Thermometrics RL-4504-3. It is only rated for 1 watt, but for the brief duty cycle it sees in our trucks, it should work just fine.
Dr. Lee :cool:
[ 04-25-2004, 12:30 PM: Message edited by: CleviteKid ]
In his article, MP reported his analysis and tests of adding a 5 ohm resistor to the feed to pin "C" of the controller, which added 2 to 4 seconds of glow time. For use with the AC 60G glow plugs, which heat up slowly and don't reach the same peak temperature, this extra glow time can be beneficial.
Here in Miami I have not needed extra glow time, but ever mindful of our members in colder climates (almost all of you) I have looked into a refinement of that suggestion. I have added a Negative Temperature Coefficient (NTC) thermistor with a nominal value of 5 ohms at 25C (77F). The NTC part means at lower temperature the resistance is higher (longer glow time) and at higher temperature, the resistance is lower (shorter glow time). Before installing it for testing, I first measured the resistance at room temperature and saw 4.9 ohms on my Fluke. Then I put the thermistor between two ice cubes, and watched the resistance rise to 13.8 ohms. Finally, putting it in 180F water dropped the resistance to 1.9 ohms. Promising.
In the engine, at about 80F ambient, my initial glow time was increased from about 4 seconds to about 6 seconds. Now all I need to do is to find a drive-in freezer to test the low temperature effect :eek: .
The NTC thermistor I used was from Digi-Key, and is a Thermometrics RL-4504-3. It is only rated for 1 watt, but for the brief duty cycle it sees in our trucks, it should work just fine.
Dr. Lee :cool:
[ 04-25-2004, 12:30 PM: Message edited by: CleviteKid ]