Guys I have a quick question for you all...

Background: 1986 F-350 6.9L Diesel

I bought this truck a few weeks ago and it had troubles starting..Now the previous owner has installed a push button for the glow plugs in the cab. I can try and take pics of his wiring?? I've read Ziggsters wiring diagram and cant make sense of it.

Here is my MAIN question, yesterday I jump in the truck (havent been in it for 2 weeks) and hit the glow plug button *hear a clunk under the hood* light comes on for 1 or 2 seconds and *clunk under the hood* light goes off, try and start the truck, no luck.

I let it sit for about 5 mins and tried it again, push glow plug button and *clunk* light now stays on for 7-8 seconds then *clunk* turns off. I was thinking, "ok,ok 8 seconds should be warm now!!" but it wouldnt start. It came close but didnt actually fire up.

I was wondering why all the different cycle times? Is this a controller issue or??

Secondly, I pulled the air cleaner and looked at the plugs, 3 of the 8 had a red ring around them, 2 had white and the rest were uncolored, that would lead me to beleive that some are still the originals and that I should replace ALL of them?

I think I will replace all plugs and see if that helps but wanted your opinions,

Thanks for your time,

-Joe

 

If you are going to replace all the plugs you must use Motorcraft Beru for safety and performance, you will know what I mean if you have read Ziggster's page. Not knowing how the PO wired it up we could only guess what the klunck was....possibly a relay???

 

I will try and take a photo of some of this wiring tonight.

If the GP light is only staying on for 2 seconds, and then 8 seconds the next time, does this sound like a controller issue?? I really HOPE not!

 

Pop over to this page and check out the 86 wiring info..........

http://community.webshots.com/album/202816966sObdCc

 

I had a similar problem with my 86.

The glow plug controller simply supplies power to the glow plug power relay. The relay is just a solenoid that connects battery power directly to the glow plugs.

The relay on my truck had the contacts burned internally. I had to drill out the rivets on the replay to get it apart. After I cleaned up the contacts with some sand paper it worked normally.

You have 3 problems possibly.

1. The glow plug control unit has failed. So someone has installed a simple pushbutton switch to completely bypass the control circuit and you power the glow plug power relay directly with the pushbutton switch.

2. The glow plug power relay has burned contacts inside so it still actuates (clicks) but since the contacts are burned there's no power going to the glow plugs.

3. You might have some failed plugs too!

You can easily check this by connecting a voltmeter to one of the plugs and check voltage when someone pushes the button. Don't disconnect the plugs when you do this. you want to check for voltage under the load of all the glow plugs.

Regards,

Rick

 

The 86 glow plug system is a nightmare.
It is great right up till it starts to go bad. Then the nightmare begins.
The controller is expensive, and it is in the back of the passenger side head.
Bad place to get to, it will probably break off when you try to remove it.
Then you need to remove the head to stop the water leak after it breaks.

That is the reason for the manual conversion being the best bet.

First step you should take is to replace all the glow plugs with Motorcraft/Beru plugs.
Next step is to run a wire from a power sorce to a push button.
Run the wire through the firewall and over to the passenger side inner fender well.
Right behind the battery you will see a round relay that has 4 wires hooked to it.
2 large ones and 2 small ones.
The small ones are purple close to the engine and black close to the fender, remove the purple wire and hook your wire from the push button there.
The large wires should be red on front that goes to the battery and orange ( there are actually 2 orange wires) on the back that goes to the motor.
Another thing to check is the orange wires going to the motor go through a connector close to the dip stick. This connector will get a bit of corrosion inside and the large amount of current the glow plug system draws will melt the connector. Once this happens your best bet it to cut the wires off close to the connector and use a split bolt to connect them. Tape it up good and no more problems with bad connections.
You can get a copper split bolt wire connector at most hardware stores in the electrical department, you want a small one that will handle 4 #8 wires.

 

You are so RIGHT!

I didn't keep my 86 long enough for this to happen. If I had I would have designed a much simpler temp/timing circuit. Sometimes automotive engrs make things WAY too complicated!

 

Thanks guys! I replaced all 8 glow plugs, the old ones I pulled out were a mix of Champions, Bosch and.....Autolites All came out ok, and I replace they all with Beru/Motorcraft.

One small update, the truck wont start, if I plug in the block heater she fires right up but trying to do it with just GPs doesnt work, its cool here and the truck hasnt moved in a week. Problem is the GP light only stays on for 1 second and it should be on for about 8 I think...Maybe rick is right about my contacts being messed up? I can still here them "click" on and off in unison with the WTS light.

Rick, can you give me a little more detail on hooking up the meter to test if the GP's are infact getting power when I press the button? I have an Ohmmeter and a test light...

Dave, electrical jargon doesnt work well with me heh, dont know crap about it...I am going to print off what you;ve said and a friend to explain it to me. I think I could follow step-by-step but the main problem is the previous owner and all this wild wiring he has done

-Joe

 

Joe,

This is probably a good time to get yourself a good digital multi-meter if you don't have one. They're not expensive and you should be able to get one at Radio Shack or any auto parts store. It doesn't have to be an expensive one.

What you want to do is check your battery voltage when the glow plugs are powered up.

You'll have to have someone turn on the key while you check your battery voltage so you can see what the terminal voltage is under load.


Then connect the volt meter to one of the plugs (connect the volt meter negative lead directly to the neg-lead of the battery) and determine the voltage being supplied to the plug. It should be the same. If it's a lot lower, you have a poor connection somewhere in the form of a burned relay contact, corroded conector, or poor ground connection.

Those glow plugs can draw around 20A each (8 glow plugs draw 160A) so a poor connection or a burned relay contact will dramatically reduce the voltage at the plug. The glowplug controller time on is determined by coolant temp. The lower the temp the longer the controller supplies 12v DC to the glow-plug power relay.

I went out into the garage and found the old solenoid I removed from my 86. I had taken it apart to clean up the contacts inside while I was obtaining a new solenoid.

It has 2 small connections with #10-32 nuts on it and 2 large connections that are probably 5/16" NC nuts. The larger connections are for 12v power directly from the battery and the other one goes directly to all 8 plugs.


One of the small connections will be 12v power coming from the controller and the other one will go to directly to ground. (If there's only 1 small connection for power from the glow plug controller, then the solenoid is grounded internally and you only need to supply 12v+ to it with a momentary switch or button) You can bypass the controller by disconnecting the 12v wire coming from the controller and connecting it to 12v directly with a momentery toggle switch or push-button switch.

THIS IS A FAIRLY DANGEROUS WAY TO POWER YOUR GLOW PLUGS!

BECAUSE, Holding it on too long runs the risk of burning up a plug(s). Some plugs if burned up, MAY swell to the point of being IMPOSSIBLE to remove without breaking off in the precombustion chamber leaving pieces of the burned plug in the chamber or in the cylinder. Newer manufacture plugs don't do this I'm told.


I would never operate my glowplugs this way. I would replace the controller if required. I never had to do this on my 86 though. I just replaced the solenoid.

Any 12v starter solenoid will work to replace the power relay. That is what I replaced my glow plug solenoid with. I did not replace it with the ford part. Starter motors draw FAR MORE current than glow plugs so the solenoids are rated for far more amps!

If you need to replace the controller, I found this link:

http://www.o-f-i.com/index.php?pid=12 <copy and="" paste="" this="" url="" into="" your="" browser="" )="">

copy/paste the above in your browser. I have no afiliation with the above company. There's a multitude of companies that sell those controllers. Find the cheapest one that will ship cheap!



Hope this helps!

Rick








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Rick, just a quick update for you.

Last night I went and tried to start it, just for the heck of it I guess. I jumped in, and wow, the WTS light stayed on for 8 seconds. I thought "great!" and turned it over, well she roared to life for about 1 second (first time shes started without blockheater/ether assistance). I know its not air leaks because she runs like a champ once shes running.

Anyways, I am going to test to make sure power is getting to the plugs tonight, just thought I would throw this out there to see if it narrowed down my options. The problem seems to be sporadic, the light stays on for 1 second one day and 8 second the next even though the air temps havent changed.

I will report back in the morning!

-Joe

 

Great!

It appears that most of the GP's are glowing at the right time now! This *could* be an indication of the relay intermittantly working. The timing circuit should not affected by the power relay. If it was burned contacts in the relay it would still "click on" for the correct time for the ambient temp, but no current would be going to the plugs.

It sounds like your timing circuit might be intermittant. That's the little screw in device mentioned by someone earlier in the pax side head near the firewall that is actually a thermostatically controlled solid state relay that provides 12v power to your GP plug power relay. I never did have to remove mine but if I remember correctly they are sealed and must be replaced if defective. I know a lot of them did have problems back then.



RM

 

Sorry on the 86 it is not a solid state controller. That is the 87 and later controller.
The 83 through 86 controller screwed into the rear of the passenger side head.
The end of the controller was in the coolant jacket to sense the coolant temp.
That is why I said it is better to run the manual control than trying to get it out.

It has been rusting into that hole since the truck was built in 1985 and has never been moved. If you try to remove it, and it breaks off, you have to take the head off the engine to get it out. You have to get it out to plug the hole or all the coolant runs out through the controller after it breaks.

To remove and replace two heads on the engine takes about 22 hours of solid wrenching with air tools and a helper. The difference between one head and two heads is about 2 hours. The passenger side head is the hardest one to do in the truck.

 

Dave,

Don't be sorry! I was the one that was wrong! I don't remember ever trying to remove it though. Is the actual part that screws into the head metal or plastic?

Once you get it out you could just put a pipe plug in it's place if you didn't want to replace it. What a bummer if it breaks!


It's impossible to tell from the schematic what's inside.

http://www.intellidog.com/dieselmann/glow2.jpg

I just assumed that it was a simple RC timing circuit that does the timing. (the R being the integral temp sending device(resistor). You would have to use a switching transistor or SCR etc to turn the power relay on and off....This is probably how the 87+ works....How does the 86 work then?)
[Possibly a little bi-metal set of contacts that actually heat up and open after a few seconds.... the colder the ambient is the longer they stay closed?]


In any case it appears that Joe's problem might not be the controller.


I have been toying with the idea of putting a 6.9 or 7.3 in my 55 F-600. A neighbor has offered me an E4OD out of a super duty and I think properly rebuilt that E4OD would work well in my old truck behind a 6.9.

It appears that I would need to build a better glow plug controller though....and mount it in a better place than in the back!

 

Update for anyone whos following my thread

Last night I did some tests. First, I took my test light, clipped the ground wire on the neg batt terminal and then touched the GP connector, it didnt light (it shouldnt)...then had my girlfriend hit the GP button and the light lit up for as long as the GP's were on. Problem is, its only getting the power for about 1 second as usual. I can hear the relay click on, then off...

So it sounds like my controller is going bad, I guess my only option is to bypass it and control the glow time manually???

Cant wait to get this solved and have my truck back,

-Joe

 

Yes,

Unless you could remove your old controller easily (and evidently you wouldn't want to try very hard unscrewing the old one for fear of breaking it off in the head!), You'll have to just bypass the controller and use the "push-button" method. You sure don't want to have to pull that right head!! (that's probably what would have happened to me if I tried it!)

We're lucky to have people on here have "been there/done that"


Good luck!


Rick