glow plugs

danny in draketown · May 4, 2013

picked up an 1989 f 250 7.3 lt deisel to haul my tractor with. and there is a pull coming up on the 25th. the glow plugs dont work. some one bypassed the ignition switch and put a push button to start it with. when i turn on the key the relay clicks and in about 15 seconds it clicks again but no power to the glow plugs, but when i push the button to start the truck i get juice to the glow plugs. any suggestions

ben there · May 4, 2013

could be bad contacts in the glow plug relay OR whoever did the wiring left something disconnected
the timer is working,thats why you hear the relays clicking.

danny in draketown · May 4, 2013

its a new relay and the 2 small terminals get juice to them but neither of the large terminals ever light up

VicS · May 4, 2013

My son has traded for quite a few power-stroke Fords. I would ask on the Ford diesel forum first. That said. I would try another Ign switch first. Most of his always need a new relay and glow plugs. The timer seems to be working (without it the glow plugs will burn up) Good luck Vic

rrlund · May 4, 2013

There's a $200 Ford only sensor at the rear of the intake manifold. It goes in to the water jacket. I had to change the one on mine a few years ago.

RWT · May 4, 2013

If I understand you right it sounds like the glow plug controller has been bypassed.

I would hook battery power to a switch that applies the glow plug relay separately so I could heat the plugs and then crank it. A lot of times 5 to 10 seconds will start the one I am around (84, 6.9) and the controller always held on a lot longer.

The plugs are lasting longer this way.

RT

John B. · May 4, 2013

If all the glow plugs aren't working the relay doesn't work correctly either. Disconnect all the glow plugs and test them individually with an ohm meter or test light. Test light has to be hooked to the positive post on your battery. I the light lights up when you touch the glow plug, it's good.

One other test you can only do with the glow plug out of the engine is hook it to a battery and see if the tip turns red. Sometimes the stem turns red before the tip and then it is a bad glow plug.

Mike (WA) · May 4, 2013

I was told there are three different sensors involved with the glow plugs, ranging from expensive to outrageous, and installation ranging from easy to impossible. They kept malfunctioning in my '85 6.9, resulting in glow plugs getting energized at 70 MPH on the freeway, and burning them up. After a couple rounds of that at about $300 a pop, I wised up and bypassed the sensors completely, and just ran #10 wires from the big poles on the relay to a push button switch that I mounted under the dash. Press it for about 5 seconds when engine is cold, if truck doesn't start, repeat. End of problem. You'll drive yourself (a) crazy and (b) to the poorhouse trying to keep sensors in that rig. Just do the pushbutton and you'll be fine.

Also, there is a procedure for checking the glowplugs in place, with an ohm meter- I think good ones will show 2 ohms from tip to ground, bad ones will show open circuit (infinite ohms). I've got the Navistar service manual out in the shop- I'll go confirm that if I can work up the energy.

glow plugs

danny in draketown

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ben there

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danny in draketown

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VicS

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rrlund

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RWT

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John B.

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Mike (WA)

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