6.9 Glow Plug System problems

[Baxter]

Hey everyone, I know there is a lot of glow plug discussion on here but I'd like to explain my situation and see if any solutions come up besides bypassing it to a manual switch ... sorry for the long winded explanation.

1985 stock 6.9, truck became hard to cold start after about a year of normal operating and glow plug light wouldn't come on, just cranking and cranking forever so I replaced the gp relay unit ... fixed, so I thought, everything was back to normal... then couple weeks later same no cold start issue so I replaced all the glow plugs with motorcraft brand and still nothing on cold ... I should mention truck has always started right up and ran fine when warm. So now I replace the controller about a month ago, the solid state unit in the back of engine bay screwed into engine block. Fixed so I thought, everything back to normal, gp dash lights up and cycles thru normal, on for about -5 sec. off and back on for 5 sec. etc. there is also an audible clicking noise each time it lights up which has been normal since I've owned the truck, crank it and it fires right up quick, cold.

Now all of a sudden on a warm start the other day the gp dash light stays on indefinitely and there is no clicking sound. Truck starts easy because it's warm.. I then disconnect the relay so as to keep the plugs form burning up if they were permanently hot for some reason. Get home and sit over night to a cold start situation in morning...and nothing just cranks and cranks and light stays on indefinitely. Replaced the relay again because I had a new unopened one. Same, nothing. Tested a couple of the glow plugs and they appear to be dead. Was now going to replace the controller and plugs again but that feels stupid.

Questions:
1. What would the difference be between light not coming on at all and light staying on and not going off? both are accompanied with no start situation.
2. Is the standard clicking noise that is no longer there, coming from the relay unit or the controller?
3. All new components, relays, controller (Standard brand lifetime warranty) and glow plugs (Motorcraft) why would they fail so quickly?
4. Haven't installed an all new wiring harness yet, didn't think that would be the culprit ... looks in good condition wires, clips etc. would that cause any of this ****?
5. Is there an easy away to test the relay, controller and the harness in place on the engine before I throw more at it?

Thanks for your help!

 

[IDIBRONCO]

1.) when your light didn't come on, something (the relay) wasn't working. Since your light is now on all of the time, that means that your controller has stuck in the on position, like they have a habit of doing. Now your new glow plugs are burned out. They were burned out way before you got home and unhooked the relay. That's just the sad truth.
2.) It's the relay that clicks when it activates. I have my Blue Truck (1985 F250) on manual control. I don't even have a controller and it still makes the click. Yours isn't clicking now, because it's always activated.
3.) I can't answer why the controllers fail so quickly/easily. All I know is that they do and that's (most likely) the reason that Ford switched to a different glow plug system. It's also why so many people switch to a manual control for their glow plugs.
4.) I would guess that if the wiring, especially at the large plug that's right off of the passenger's side of the engine, all looks good, it probably is. I think that since your light is on, the glow plug system is working. You can check to see if you're getting power at the glow plugs. If you are, I guess that your wiring is probably good.
5.) Since your glow plug light is on, I'm guessing that your relay is working. Try unplugging the controller and turning on the key to see if the glow plug light is still on. If it isn't, there's your problem.
Sorry to have to tell you the bad news.

 

[Baxter]

This is great feedback thank you. What's crazy is I only drove it for about a block before noticing the light was full-time on! then pulled a wire off the relay, light then is off for good until I reconnected it. I guess a short distance with the gps stuck on fries em.. I will go ahead swap out the controller especially since it's warranteed and new plugs and report back ... I have been looking for nice easy instructions for wiring up a manual dash switch but haven't found one yet ... what do you do with the controller, just unplug it?

 

[franklin2]

You need to find that purple wire going from the controller to the glowplug relay on the pass side inner fender. Unplug it.

Extend the purple wire or put a new wire on the glowplug relay where the purple wire went, and run it into the cab to a momentary pushbutton.

On the other side of the button you need to find a power source that is 12v with the key on. You can get this from the fuse box, or something else you may have already under the dash. Run this power to the other side of the momentary switch. Done. You can do what you want with the controller. Leave it, take it out, it's not going to do anything anymore if you make the above modifications.

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[IDIBRONCO]

Yes. Just leave it unplugged. Here's a couple of picture from my truck. In one, you can see the plug from the old controller even though the picture is blurry. I just took these. It's the black and light brown colored piece. It wasn't hooked up when I bought the truck and, since it now has a 7.3 in it, there isn't even a controller. It's not needed. The other picture is the glow plug relay and this is how the previous driver powered it. The orange wire is from the self returning toggle switch (a push button works the same way). It's attached to the small terminal that's on the engine side of the relay. From the factory, there was a purple colored wire here. In fact, when I put my first 85F250 on manual control, I cut the purple wire and used the factory attachment to this terminal. Run a fused power wire to your push button, then run form the other side of the button to this terminal. Unplug the controller and you now have manual glow plug control.

 

[Old Goat]

83 - 86 have the GP Controller that isn`t too reliable for the long haul.
Read several threads when I first bought the 86 about the Controller snapping off when trying to unscrew it. Now you are in deep dodo having to dig out the broken threaded part.
At PNP I tried to take them out of 3 different 6.9`s. 2 snapped off and one came right out.
So with this knowledge of fear, I ain`t touching mine.

Then the ole swelled Glow Plug problem, that fear kept me wanting to try removing them. Finally I had a moment of bravery and removed the first one and came right out, and was a Auto-Lite, just sooty on the end. Next 7 came right out, evidently the Controller was not working.

Threw in some ZD-1 plugs, and wired it manually and has worked the past 4 years with the same plugs.
Also be sure to use some Anti-Seiz on the threads of the plugs.

As franklin2 and IDIBRONCO said, I wired my manual set up the same.
where your WTS Light is, to the left is a flat place. drilled a hole for a Momentary Toggle switch. (Used a black plastic one, and blends and not noticeable)
Ran a wire from it threw the FW over to the GP Relay. Cut Purple wire 4" back, and soldered the wires together and Heat Shrinked it. Then I could use the Purple wire end to connect it back onto the relay.

For the Pos + side, I had eliminated the water/Filter next to the Brake Booster, and used the red Wire which is hot with the key on. That wire goes to the other side of the Toggle. Also on that wire installed a inline fuse, one of the rubber ones with a moisture cap for a spade fuse. NAPA has them.

I also buy Heat Shrink by the 4ft sections in different sizes. I slide these over the new wires I run to cover up the colors, so the engine doesn`t look like some one threw a plate of Spaghetti on it. Cleans it up.

Here is a YT Vid, testing a ZD-9 plug, leaving it on for quite a while to show the longivity of them.

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Goat

 

[BeastMaster]

A couple of years ago, I ran into what I considered such an unlikely scenario I have been reticent to talk about, lest I come off sounding like a fool.

It started innocent enough. Just a GP relay failing to close contacts when it's coil was energized. Yeh, the most common failure mode. Switching 200 amps will erode the contacts. So, I replace just the relay.

It seems to work. For about a week. Then the battery fails. Replace that. Then the alternator fails. Replace that. It starts getting colder. The engine has gotten much harder to start. Diagnose glow plug failure again. They are getting voltage.

What the heck? I'm not even trying to start! Why aren't they even drawing current? Every one of them has burned open!

I examine why. It's that relay I replaced. This time it's contacts have welded closed! It's what the parts store gave me as the replacement relay.

This is getting insanely expensive.

I doubt my own sanity now. I take it to a professional who replaces the whole glow plug controller unit as well as all eight glow plugs. But now I am really gun-shy and very observant of sound pitch changes of my electric fuel pump and my voltmeter.

At that time, it was one year since this train of woe first showed up. Guess what? I start noticing my fuel pump sounding off-pitch, lamps dimming, and voltmeter dropping to about 12 volts ( usually about 13-14 volts when engine running ). Alternator failing again?

Shut down. Attempt restart. Why is voltmeter so low? Nothing else on.

Batteries are almost brand new. 10 volts? Should be a bit under 13 volts no load, until engine catches and alternator begins feeding current to the battery.

I consider that something heavy has got to be loading the battery. Glow plugs again?

I've been keeping a wrench handy that fits the batteries. I disconnect the negatives on both. The terminals are warm???

Nice spark when disconnecting the last one.

Ok..something is bad wrong with my main battery rail. The Alternator feeds it, and it's not smoking. The starter motor isn't hot either. Gotta be the glow plugs.

Nothing on my van can pull that much current for long and not get smoking hot.

I've just been down the glowplug road, so I remove the doghouse ( van ), and guess what... Contacts welded shut. Again!

Brand new expensive Motorcraft.

Professionally installed too, just because I wanted to eliminate my own ignorance as the source of my woe.

Ok. Two consecutive failures of the same type from what I thought were completely separate manufacturers? I get the idea some bean counter cheapened the relay ( like swapping silver for aluminum contacts ). But, there it is, battery rail shorted right into the glow plugs. Neither the key or controller have control of it. The contacts are closed whether or not the coil has power.

Maybe there's a single factory making a bad design relay, and many resellers getting them and branding them?

That neatly explains my plethora of problems. Dead batteries. Blown alternator. Blown glow plugs. Blown starter.

A heathy set of glow plugs will pull 200 amps from the battery during startup.

Keep a clip-on ammeter handy!

Although I have a fancy clamp on DC ammeter, it's way overkill for this kind of thing. Has anyone seen those old tractor ammeters that have a little magnet in them that reacts to the current flowing in wire placed in a slot in the back of the device? They weren't all that accurate, but are incredibly simple and rugged.

If you get one of these even close to a magnet, the needle moves.

And you don't have to cut the wire. Just get this thing close enough to a wire with DC current in it and the meter will deflect.

I like to get one. For seeing what kind of field around glow plug wiring.

Anyway, I ended up using the same contactor Wes puts in his kits, and going manual control.

That was last year. The system has worked perfectly since the change out.

I have waited a bit because I wanted to make damn sure my woes were gone before directing anyone else down my quite expensive wild goose chase.

If I overdid this post and it's deleted, I'll take it as not to post diatribes like this anymore.

 

[IDIBRONCO]

Read several threads when I first bought the 86 about the Controller snapping off when trying to unscrew it.

Yep. I've seen that too many times. In fact, when I first bought my Blue Truck, it was in January. The heater didn't work when it was cold outside, by the time that it warmed up to around 35, it started working ok. I finally decided that the heater core must be plugged. After driving into work, I left the engine running, opened the hood, and grabbed a heater hose. Sure enough, it was only lukewarm. Before closing the hood, I grabbed the other heater hose and it was the same temperature. I knew then that it had to be a thermostat that stuck open. When I was replacing the old thermostat, I saw something that looked like it was made of pot metal and had threads on it. The only thing that I could think of that looks like that and could have gotten in the cooling system is a glow plug controller. The glow plugs were already on manual control when I bought the truck so the previous driver (the guy I bought it from owned it for about 2 1/2 years and didn't drive it once) must have gotten tired of glow plug problems and installed a manual control.

 

[Black dawg]

Here is a YT Vid, testing a ZD-9 plug, leaving it on for quite a while to show the longivity of them.

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Goat

From what I have seen, they dont hold up like this in real world use. With the factory controller setup they last pretty good, but overglowing them with a button or even just getting on the button a second time too soon, will take them out pretty quickly.

 

[Brian VT]

...overglowing them with a button or even just getting on the button a second time too soon, will take them out pretty quickly.

What intervals are best for the life of the glow plugs vs getting a clean burn going?
I've been holding about 8 seconds (in winter) and if it doesn't fire up with 2-3 seconds of key then I give it another 5 seconds of glow and then it usually fires right up. Then I give it 3-5 seconds of glow if it sounds like it needs a little cleaning up.
Am I stressing my plugs?

 

[Black dawg]

What intervals are best for the life of the glow plugs vs getting a clean burn going?

Really a hard question to answer for sure, because of old/new wiring and voltage drop issues. Generally what ever it takes to start cleanly. They were on in my truck for almost 18 seconds this morning at 20 degrees. Seems like a long time, but old wiring does this.

 

[Baxter]

Thanks fellas. Dumb question but I turn the key to on position before depressing the manual dash mounted toggle switch correct? And then curious how just re-wiring up that one small wire on the relay bypasses the controller unit? Seems like it would still relay power to the controller...? Do I need to make sure it is unplugged or can I leave it plugged in? Definitely going manual! I'll keep ya posted. Appreciate the clear simple consistent instructions to wire this thing up.

 

[Old Goat]

No question is dumb. ask away, that is how we learn.

Your 85 Controller is the same way my 86 is.
Reread how I wired it in post #6.
I eliminated the water Filter/Trap that was factory installed. Actually some prior owner just looped the 2 hoses together. The plug that goes to the filter has 3 wires, and the red one is hot with key on.

You can use what ever wire, or fuse connection that is hot with key on.

So yes, you will need the key on, for the Toggle to activate the relay.
The purple wire is removed, I guess it goes to the old Controller, by removeing it, it takes the Controller out of the system. Mine is still there with the plug still plugged into it.

My wait to start light does not work, but I know how to count to 6 Seconds in the summer and 10 seconds in the winter to activate them.
So far they have worked just fine the past 4 years or so.

The Purple wire connector, just pushes onto the studded post of the Relay. You can pull it off and set aside, and use a ring terminal and nut. Or as I did, cut the purple wire back 4" and soldered it to the new wire. Then I just pushed on the purple wire old connector.

Be sure to add a Fuse to be safe.
I used one of these, rubber cap keeps is dry.
Think I got it at NAPA

https://powerwerx.com/atc-ato-inline-fuse-holder-12-gauge-red

Goat

 

[Baxter]

Hot with key on got it ... I will re-read post 6 again. Thanks @old-goat .. I will follow up after this freakin rain stops and I can work on it

 

[IDIBRONCO]

The purple wire is removed, I guess it goes to the old Controller, by removeing it, it takes the Controller out of the system. Mine is still there with the plug still plugged into it.

I suppose that you're actually right. I'm paranoid enough about these things that I'd unplug mine anyway if I had one.