85 6.9 glow plug killer

[we287gn]

So Fellro you have given. Me some options on glow plug set ups. Recently. I have been unhooking the controller from the relay after I get it running..and I believe I still have lost my glow plugs again.
Is being on too long the only thing that can kill a new glow plug??
Thanks

[Fellro]

The only thing besides junk glow plugs is having power applied too long, making them heat up too much. Now if ether or such were sprayed in after the glow plugs had heated, it would definitely case damage to them, as well as motor problems potentially.

[we287gn]

Originally Posted by Fellro

The only thing besides junk glow plugs is having power applied too long, making them heat up too much. Now if ether or such were sprayed in after the glow plugs had heated, it would definitely case damage to them, as well as motor problems potentially.

Hi Fellro .I put this last batch of plugs in and have not used ether.
So I thought I was hip to the problem...the controller would cycle like it should , it just wouldnt stop cycling...I thought for sure I found out what was killing the glow plugs for the previous owner..I also figured as long as I ran under the hood and unhooked the controller from the relay I would stop any premature glow plug failure.. (once it was running)
Apparently this is not the case..I have managed to kill all the plugs. the funny story is this happened to the last two owners..ANd the controller had been replaced..
So even though the controller never stopped cycling it would switch on and off the proper amount of seconds..It never left the plugs on continously.
I will most likely still wire a switch in, but at this point I need to understand what killed them ? ALL? unless cycling on and off even at the correct intervals on a warm/running engine would do it??? its possible that could have happened.
Want to be certain before I go dump more cash on glow plugs
BTW i had 4 AC delco and like 2 motor craft and 2 others came from NAPA i think..Now they are all dead
Thanks in advance for any help
PS I think I am having and alternator problem as well...The field seems to be putting a drain on the battery and I am getting flickering lights..not sure if thats the regulator or the diodes/alt itself..the onboard ameter seems to read fine, have to put the volt meter on it

[flareside_thunder]

Have you tested the "dead" glowplugs out of the truck? Hook hot to the connector and ground the thread body, if its hot, they're good. DO NOT TOUCH THE ELEMENT TO FIGURE OUT IF THEY'RE HOT. I would bypass the controller, like I have, completely.
http://www.oilburners.net/articles/glowplugbypass.htm

[Fellro]

The glow plugs do not need to be on any more than to start it, and then a little bit after. If they continually cycle, it will shorten their life just like starting it and only running it for a short time for a lot of times would. They will generally heat up and burn out if held on continuous, regular constant cycling really isn't much different, and if you consider the heat of combustion in there as well, it is pretty warm.

The ground side small terminal probably is just for the light, hadn't thought about it. That is not the proper way to control the relay though, and really, not that effective. If done correctly, the ground side will have no effect, as it grounds through the base, that little wire is not enough capacity to handle the duty of energizing that big relay. The glow plug relay works just like the starter relay/solenoid on the fender.

[we287gn]

Originally Posted by flareside_thunder

Have you tested the "dead" glowplugs out of the truck? Hook hot to the connector and ground the thread body, if its hot, they're good. DO NOT TOUCH THE ELEMENT TO FIGURE OUT IF THEY'RE HOT. I would bypass the controller, like I have, completely.
http://www.oilburners.net/articles/glowplugbypass.htm

Hi Flareside ..I havnt tested the plugs out of the truck, but I am pretty certain they are toast.I am bypassing the controller now.But it did not matter this last time around. 4 new AC plugs worked this chili morning and they were gone this afternoon...i am starting to think there is an engine condition causing this??? and they were mixed some AC some other brands..so i dont think its a brand issue

Originally Posted by Fellro

The glow plugs do not need to be on any more than to start it, and then a little bit after. If they continually cycle, it will shorten their life just like starting it and only running it for a short time for a lot of times would. They will generally heat up and burn out if held on continuous, regular constant cycling really isn't much different, and if you consider the heat of combustion in there as well, it is pretty warm.

The ground side small terminal probably is just for the light, hadn't thought about it. That is not the proper way to control the relay though, and really, not that effective. If done correctly, the ground side will have no effect, as it grounds through the base, that little wire is not enough capacity to handle the duty of energizing that big relay. The glow plug relay works just like the starter relay/solenoid on the fender.

Well My relay definately is not grounded by the base like the starter solenoid is...I mean the base is grounded to the chasis, but its not making the conection for the solenoid .it wont energise if the small ground terminal isnt on.. not sure if this is correct but the controller wire is no bigger thats supplying the 12v to switch it on...anyway like stated above I havnt used the contoller at all, rigged me up a button and it doesnt matter got one cold start out of 4 new plugs and they are all now gone.
Really has me baffled
Again wonder if this is an engine thing or electrical...cant see how it can go wrong..
Two of the plugs were swollen at the tip again as well
Again thanks for all the help, hopefully can figure this out soon
BTW new regulator and alt seems to be charging fine...so far fingers crossed

[Fellro]

You can use a simple resistance meter to find if they are burned out, no continuity means they are burned out. The wire size to the small terminal side is not an issue, as it does not draw much amperage through to simply move the contacts inside the relay. Some relays like that require the ground terminal like you describe, so may be the case here. In the case of a starter solenoid/relay, it is used to keep from turning the vehicle over if either the clutch isn't depressed in the case of a manual with a clutch safety switch, or an auto not in neutral or park.

Engine conditions won't cause the tips to swell, that takes enough heat to cause other significant damage. By any chance has the glow plug harness been replaced? I mean the heavy wires that go to the glow plugs themselves. The original wires on these trucks were a resistance wire, and will burn out the glow plugs if a full 12v is applied. I don't recall the actual value, but I want to say they are only 6v plugs. I do know that if somebody replaced the original wiring, it will kill plugs very fast. I have heard suggestions of finding military spec plugs, but not always the easiest to do. Military vehicles tend to be spec'd at 24v, so you can apply a full hit on them, and not burn them up. I have no clue where to find such, or if they exist for IH motors.

[we287gn]

Originally Posted by Fellro

You can use a simple resistance meter to find if they are burned out, no continuity means they are burned out. The wire size to the small terminal side is not an issue, as it does not draw much amperage through to simply move the contacts inside the relay. Some relays like that require the ground terminal like you describe, so may be the case here. In the case of a starter solenoid/relay, it is used to keep from turning the vehicle over if either the clutch isn't depressed in the case of a manual with a clutch safety switch, or an auto not in neutral or park.

Engine conditions won't cause the tips to swell, that takes enough heat to cause other significant damage. By any chance has the glow plug harness been replaced? I mean the heavy wires that go to the glow plugs themselves. The original wires on these trucks were a resistance wire, and will burn out the glow plugs if a full 12v is applied. I don't recall the actual value, but I want to say they are only 6v plugs. I do know that if somebody replaced the original wiring, it will kill plugs very fast. I have heard suggestions of finding military spec plugs, but not always the easiest to do. Military vehicles tend to be spec'd at 24v, so you can apply a full hit on them, and not burn them up. I have no clue where to find such, or if they exist for IH motors.

interesting stuff on the mil spec plugs..i do have 86 shop man here and it states they use a 6v plug for a quick heat....not sure on the harness it does look original, i am getting a little drop after the harness but maybe less than a half of a volt, so pretty much 12v getting to the glow plugs..
did a little searching online , it seems i am not alone in this problem not just 6.9 ..some 7.3's toasting all the plugs in short time...most answers were use only beru/motorcraft plugs....but i have a hard time swallowing that one only because i owned an 86 and never changed glow plugs in the 4 yrs I had it and previous owner replaced only a few over the years and he always deals with whatever napa gave him...think they may have been champion ..not sure..but defiantely mixed bag..
on my 85 this is something that happed to the previous owner as well..and he has owned the truck since new, it was only in the real later years that the glow plugs started letting go like this, but i will try to investigate the harness idea..thanks

[flareside_thunder]

How long did you hold the button down for this morning?

[we287gn]

Originally Posted by flareside_thunder

How long did you hold the button down for this morning?

I held them.on for.apx 6-9 quick.seconds in fear of leaving it on too long..I got those numbers frok the 86 shop manual.
Also called my bud who was the previous owner of my old 86 that never had trouble.he sId he used autolite and champions. And in 4 yrs of owning it I never had a glow.plug issue
As of right now I am not buying into the brand thing..too wipe em.all.out..mixed bag of brands..there is something else going on.here..
I was reading about the injector timing being.off.but I know.nothing about or have the special tools to.check.it