9 volt glow plugs on 12 volt system??

Anonymous-0 · Jul 4, 2010

Hey folks,
Original glow plugs for my tractor are real expensive. Someone was selling adapters that allowed you to use modern/faster acting plugs in them by redoing the wiring a little (direct from battery to each plug). Anyway, there are two options for part #'s to use. One says "9 volt glow plug" and the other doesn't specify.

Can I use the 9 volt ones without burning them out or do I need something to step down the voltage? If so, what would I be looking for and how would I use it (voltage step down)?

Thanks, Dave

Bob · Jul 4, 2010

9 Volt glow plugs are commonly used on 12 Volt systems for FAST heating. They are used with a controller that consists of a timer and a temperature-sensitive circuit that varies the "ON" time based on ambient temperature. Without that timing control they will overheat and "pop" putting pieces/shrapnel in the pre-chamber.

Look up "Bosch dual coil glow plugs" and see if you can find one for your application.

They have a heating coil AND a PTC resistance coil that drops current as they heat up to self-limit their temperature.

There are other manufacturers of similar units.

Wilson · Jul 4, 2010

Got tired of rplacing 12 volt glow plugs on chev 6.2 went to 24 volt had to cycle 2 - 3 times in coldest time worked fine one cycle warmer weather. Those plugs lasted for years till sold the truck. saved a lot of money and chance of old plug breaking in cylinder

Brad Gyde · Jul 4, 2010

I keep getting told that the glow plugs in the old 6.9/7.3 IH diesels in ford pickups are 6 volters.. True or not, I dunno.. but if they really are, I'm sure the 9v ones would be fine.. Just don't lay into the button that activates the plugs.

When my "activator" went bad on my 6.9, I put it to function off of a push-button (only a $130 savings.. and since I'm the only driver, no problem).. in freezing temps, 10 seconds on the button and fires right off.

Still don't understand for the life of me why the IH's won't start without the glow plugs, even in the summer time.. AND NO!! My engine is not "tired".. even my work truck with just over 100k is the same way :/

Brad

Bob Bancroft · Jul 4, 2010

I once had a diesel Chevette. It was an Isuzu engine I believe. Cold weather starting was always a problem. The replacement glow plugs were a lower voltage than the nominal 12V system. Almost seems like the were 6V !! I questioned the supplier and they explained that was right, they got hot rapidly. They generally only gave out when I got stupid and jumped or boosted the car and voltage went above 12.
Similarly, once when converting a tractor from 6 to 12 volt, I forgot to change the headlight bulbs and they actually worked(they probably wouldn't have for long, they were really bright!) But the instant I started it and voltage went above standing battery voltage, they blew!

Bob · Jul 4, 2010

Someday, when a broken off glow p[lug gets embedded into the top of a piston you will realize the folly of the $130 "savings" of eliminating the glow plug controller.

Been there, seen that. NOT pretty.

Brad Gyde · Jul 4, 2010

Bob.. Can't stress the small stuff... LOL..

Actually, since doing away with the 500k+ 6.9 and swapping in a 7.3, I now have a controller.. But still do have the push button wired in.. Just in case that day I'm out in the field and the controller gives out.. It has been known to happen..

Brad

Bob · Jul 4, 2010

Yep, I hear you with the controller problems.

I've retrofitted a few Chevy 6.2's and pre-Powerstroke Fords to a more modern controller and dual-coil GP's. They work well compared to the old controllers GM or Ford used.

Brad Gyde · Jul 4, 2010

Well.. when I updated to the 7.3 and the more modern setup, I really thought I'd be impressed.. but, in all actuality, the old 6.9 and the old setup (before the controller went bad) started easier.. Seems like I am cycling the plugs a couple times in the cold these days.. and the 6.9 had next to no compression to boot.

I'd be interested in how you'd go about updating.. what would I need to buy and how would I go about it? The truck may be old and beat up, but at the time, it's my service truck, and I'm planning on keeping it set up as such (at least till it breaks in half) and something that'd make it start up better would interest me

Thanks,

Brad

9 volt glow plugs on 12 volt system??

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