# 97 f25 7.3 Glow Plug Help



## welj31 (Jan 20, 2009)

So here is the deal. I Picked up a 97 7.3 Turbo Power Stroke 
Reg Cab 4X4
. Runs well but wont start unless its pluged in when temp is below 32f.
I was told it COULD be the glow plugs. After reading a bit I have found it COULD be a few things. I should add at this point this is the first diesel I have owned or needed to work on. 
While reading up on it I found the glow plugs COULD be in one of two diff spots. I dont see them on the top of the motor so I am thinking they may be under the valve covers?
First I need to know the most likely part to fail (glow plug, control Mod or ??).
Second I did a search but did not turn up a link for replaceing them. My understanding is there are certain steps that MUST be followed when replacing them (oil, coolant, fuel). Does anyone have a link to a step by step post on the job?
"Wait to start" light comes on and stays on for about 3-5 seconds.
Truck has 258,000 miles and is well maintained.
Thanks for any help.


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## pvtben121 (Aug 22, 2010)

welj31;1234446 said:


> So here is the deal. I Picked up a 97 7.3 Turbo Power Stroke
> Reg Cab 4X4
> . Runs well but wont start unless its pluged in when temp is below 32f.
> I was told it COULD be the glow plugs. After reading a bit I have found it COULD be a few things. I should add at this point this is the first diesel I have owned or needed to work on.
> ...


Start with the glue plug controll er they burn up alot on older 7.3


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## welj31 (Jan 20, 2009)

Where is it located and how do i test? Thanks


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## mwalsh9152 (Dec 30, 2008)

start by checking the glow plug relay, its on top of the engine, just to the passenger side of the center. You can jump it just like a starter solenoid to test it. Jump it for maybe 15 seconds, then try and start it. If it doesnt start then I would check the glow plugs. They are under the valve covers, and Im not positive how to check them, but you can ohm check them.


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## mrv8outboard (Dec 29, 2009)

Yes check the glow plug relay first. Mine had a dead spot. I watch the volt gauge to drop and the come up when the light goes out and it will start. But a simple test light would verify the proper operation of the solenoid. Now the glow plugs are under the valve covers. If you have to go there make sure you have new wiring harnesses/gaskets (the wires are the gaskets) because they are bad by now when you disturb them.


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## mjones (Nov 16, 2010)

powerstroke nation . com lots of great info for ford diesels check your relay and get motorcraft glow plugs i 've heard after i put autolites in my truck that they can swell over time and be very hard to get out


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## mjones (Nov 16, 2010)

a new uvch wiring harness would be a good idea the plastic was getting brittle on mine when i changed my glowplugs a 175000


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## blmc5150 (Nov 10, 2010)

I just installed a new Glow Plug Relay in my '03 7.3L. Check w/ a test light both posts. The one has power straight from the battery, the other should power up when the key is turned to the "on" position to pre-heat the plugs. If it doesn't light up, you probably have a bad relay. Also, you could check the 2 smaller posts by putting your test light across both small posts, if it lights up you at least have good signal going to the relay. Just my 2 cents.


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## welj31 (Jan 20, 2009)

Thanks guys I will do some testing this weekend.


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## timberjack (Dec 21, 2000)

A good bit of reading here.

http://www.ford-trucks.com/forums/424709-glow-plug-gpr-hard-winter-start-and-white-smoke-thread.html

If you're handy with a ohmmeter, you can test each glow plug without removing the valve covers. Post #17 in that thread details it. I did it last fall on a parts donor truck, that wouldn't start under 50 degrees. It had 7 bad plugs. I was surprised it would start at all.


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## mjones (Nov 16, 2010)

make darn certain you plug all of your wires in and double check them i left on loose and the truck ran like **** until i pulled the valve covers back off and found a loose wire going to an injector


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## juan91 (Feb 12, 2010)

all good info in here guys! any updates?


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## BBF-350 (Dec 1, 2010)

Connect clamp of test light to positive batt term and get wiring diagram. Prob all glow plug pins of valve cover connector on each side. Should light test light if good, if not it is open and needs replacement.


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