Hi All,

I have an 85 F250 Diesel with the 6.9 in it. 4 spd, Manual, 4x4 ...

My problem is that it keeps burning out glow plugs, all of them at once.

Here is the story. Sorry for the long post, I just want to get all the information in one place and avoid the "did that", "what happened when .." etc and save everyone's time.

I read around various forums and I'm well aware of the controller on the back of the engine and the relay on the passenger side inner fender having issues amounting to usually being stuck on and overheating the plugs.

The relay on the passenger side fender is new. The controller on the back of the engine is not.

I was using Bosch 80024 plugs not the Autolites or Champion ones that everyone on every forum spends so much time bashing.

When I first replaced the plugs, the original ones were real old, carboned up and burnt out. (Test light with clip on positive terminal to spade connector on glow plug with connector removed didn't light up, and they all showed infinite resistance with an ohm meter when testing between the spade connector and the threaded area)

So I at the time figured they had all burnt out slowly over time, and never got replaced as the truck was not running when I got it. (I have been driving it for about a year now)

In went the new plugs, the controller cycled as normal for about 10 seconds at first (it was -10c), then a couple of 2-3 second cycles. Truck fired up right away and I thought I was good to go. Took it for a 20 min drive around town and parked it for the night and plugged in the block heater.

The controller didn't cycle at all during this time.

The next morning, the truck wouldn't start. I checked all the plugs and they were all burnt out like the original ones.

I tested the harness going to the plugs and all 8 connectors showed no resistance between the relay they go to on the passenger side and the connectors (when disconnected from the plugs) At that time, there was no voltage on that side of the relay and the key was in the off position. No voltage to the plug connectors either.

I tested the connections on the controller connector. It has no voltage anywhere until the key is in the on position. Then two pins come live. The ground also tested good on the controller.

I figured something was activating the controller, so I bypassed it with a button that has to be held in to complete the circuit, which turns the relay on the passenger side on and unplugged the controller completely.

I tested the plug connectors, they have no voltage when the button is unpressed, and 12.5v when it is pressed. Figuring I solved whatever was making the controller go live, I put in another set of plugs and connected them. I checked each one with a test light as before and all tested good.

Pushed my button in for about 10 seconds, truck fired up, and I let it sit there and idle for about 20 mins.

I shut off the truck, plugged in the block heater and came back out every hour and checked both the plugs and the voltage going to them. They stayed cool and tested good. No voltage going to the plug wire side of that relay either.

I fired up the truck the next morning. It was pretty hard to start, but it did fire up. I went to work, parked the truck, no block heater this time. (About a 20 min highway drive) and when I came out that evening to start the truck, all the plugs were dead again.

I ended up using a bit of ether to start the truck, got it home and here it sits.

I don't know what is killing my plugs, they are getting voltage at some point, it sounds like its when the truck is driving but I don't know where that would be coming from unless I have some weird grounding issue that is activating the plug relay or giving power to the plugs some other way. I never see the plug light come on while driving, and it is on the same post on the relay as the plug wires.

The other thing I am wondering is that there are 6v and 12v plugs in the spade connector style. I wonder if this system is supposed to be a 6v system stock, but someone switched it to a 12v system, or if there is a resistor somewhere that was shorted causing the increase in voltage from 6ish to 12ish.

Anyone ran into this before?

 

I'd suggest updating the glow plug system to the 87-newer controller. The old one that screws into the cylinder head, when fails will remain on resulting in burnt out plugs like what happened to you. Be sure to use Motorcraft Plugs (Beru) only since the controller is designed for those plugs.

 

Hi, thanks for the reply. If I bypass the controller on the back of the engine and disconnect it completely so that now its just a really tall plug for the intake, whether it is faulty or not shouldn't matter at that point right?

Unless when operating normally it has a resistance in it that steps the voltage down from 12v to 6v, but even that doesn't really work because all it is doing is turning on the relay on the inner fender. So any resistor set to lower voltage should be between that relay and the plugs.

Does anyone know if the Bosch 80024 plugs are a 6v or a 12v plug?

I'd love to upgrade to the 87+ system, I just want to make sure that there is nothing aside from the controller or harness making things die.

Thanks again for your help!

 

in my experience, the bosch plugs are just as bad as the wellman, WAP, autolite, ac delco, and champion glow plugs .and they all cost more money than the MOTORCRAFT/BERU plugs.

 

Hi TJC,

Thanks for the info. That is one thing I haven't come across in my researching and it is one thing I was thinking of. But would crappy plugs not even last a day with the controller out of the picture?

I know each connector is getting 12.5v. I saw on another forum somewhere that one person swapped in ACDELCO 12V's which were used on olds diesels, according to him were a 12v self regulating plug that would not overheat.

Of course we all see miracle cures like that on forums and it usually turns out that person did other stuff to resolve that problem which they fail to mention and if ACDELCO falls under the garbage category, then I'll avoid them.

In your experience, when people have bypassed a failed controller and just run a button or switch to apply 12v to the relay do the glow plugs still burn out?

I really hope I am not coming across as an A-hole here, I have been working on this truck for 4 weeks now, it started when the IP decided to digest itself, I installed a new one and fixed a bunch of air intrusion stuff then the weather turned cold and glow plugs became my pain.

I really appreciate any help you guys can offer. I have always looked at this forum for ford answers, its the most accurate and reliable source of information I have found so far.

 

i have seen and heard of off brand glow plugs burn out after one start many times.
most of the time it is autolites though.


seeing as you have the controller disconnected and bypassed with a momentary contact pushbutton, i don't think they are energizing while driving, but that nay be possible. what i would do before putting new glow plugs in is mount a temporary 12 powered light somewhere in the truck where it is readily visible, and hook one side up to a glow plug wire and the other side to ground. then take it for a ride and look to see if the light comes on.
if it don't come on i would say it may have just been bad plugs.
here is a good site for the proper plugs for your 6.9
6.9 Liter Diesel Motorcraft Glow Plugs - Ford 6.9 Liter Diesel Motorcraft Glow Plug - Diesel Filters,Additives,brake rotors, and brake pads for Chevy, Dodge and Ford Diesel Trucks
one thing to remember with the push button glow plug system, is that you may only need 5 seconds glow time to start, so you can modify the glow time to suite your needs.

 

Thanks for the additional info, I'll do that and let you know. Once I know its not turning on when driving, I'll order those motorcraft plugs.

Thanks!

 

no problem!!
and please let us know how you make out.

 

Hi All,

I didn't give up on this one, it just became one of many things I ended up replacing on this truck over the winter.

I replaced the whole wiring harness for the glow plug system and my truck continued to eat bosch plugs even with the glow plug controller eliminated. I managed to get some good-ish plugs in a bunch of parts off a guy who was parting out a truck like mine so I figured I would give them a try.

I solved my glow plug problems by getting a set of dual coil self regulating ones from the states. Cost for those plugs worked out to about 1/2 of what I was paying for a set of Bosch ones. I replaced my glow plug controller with a hold in button in the cab and since then my glow plugs have not been a problem and my truck has been running well for a couple months now.

Thanks again for all your help!

 

Did you end up putting motorcraft plugs in??

 

He probably used the autolite 1109's that have been mentioned a few times.

 

Why not spend the extra $1 each and have peace of mind??

 

My Autolite 1109 dual-coil plugs have had a rough life, and they are still lighting up every morning on the stock '85 controller with the old style glow plug system.
I bought them for my first IDI, it ran for a month until the head gasket blew. I pulled them out and they sat in a drawer in my toolbox totally exposed to the elements, had wet tools tossed on them, rattled around like that for about 6 months.
About 2 weeks after the head gasket blew on my first truck, I found my current truck and ran it until it lost the head gaskets 2 winters ago.
While doing the head gasket job, I replaced the Motorcraft/Beru's with my Autolite 1109's because I had 1 of the Beru's break off in the head. Ended up bring the head to a machine shop and they drilled it out. It was pretty nasty...
After 6 months of sitting in a toolbox esposed to the elements, I threw all 8 Autolite 1109's on the battery charger. Each one was tested for 10 seconds on the first round. I let them all cool. Then the second round I tested them for 20 seconds. I let them all cool. Then the third round I tested them for 30 seconds. I let them all cool. At this point, none were swollen and they were all lighting up with the same pattern. I tested them all again for 1 minute. I let them all cool. Then the last time I held the charger on them for 2 minutes straight and they all tested fine. After cooling, they were installed in the engine.
In grand total, they have about 30k miles on them, been swapped between 2 trucks, they've been paired with an original IP and Injectors, another used IP and matched injectors, and finally a brand new rebuilt IP and all brand new BB code Injectors.
Fires up every morning. Because they are actuall a 12v plug, on the cold mornings (down in the single digits Farenheit) I have to cycle 2 times because the factory 83-86 controller just doesn't light them long enough.
I may end up wiring in a push button, but they work fine as is, so I may not.

It's not uncommon for my truck to start 10-20 times a day. I've gone thru 2 used starters and I'm getting close to finally killing this one in the truck. I have 1 more used starter to use up, then I'll go looking for more used starters or bite the bullet and buy a new one.
I'm just saying that the truck starts often enough to wear out starters and my glow plugs fire reliably every time.

That's my Autolite 1109 story...I'm not pushing the plugs on anybody, just sharing my experience.

 

Thats fine for you, but they aren't going in my IDI.

 

No worries, just sharing my experience. Not trying to be a salesman or anything.