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84 c30 with a 6.2l glow plugs wont work

Reiter1001

Chasing rabbits
Messages
12
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11
Location
Pa
Thread starter #1
I have a 84 c30 with a 6.2l the glow plugs wont work on their own I bypassed the thermo switch on the passenger side every thing else is new relay, controller ,glow plugs. If I ground the relay they work great I think I must have a ground problem any idea where I would find any and all grounds I'm out of ideas any help would be appreciated
 

Jaryd

Love my 6.5
Messages
889
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1,188
Location
Hodges, SC
#2
I wanted to post the link in the technical library for the grounds sticky but it won’t open.

I’m assuming the 84 6.2 is close to my 6.5 grounds except for the PCM ground.
Passenger side head at the back is a couple grounds, ground strap from block to frame is near starter, ground going to body is behind passenger battery, I think there is one on the firewall to. Probably a few more that I can’t think about right now. Need to TAKE APART and clean every single ground that you can find. Dirty grounds causes all kinds of problems on these trucks.
 

Will L.

Well-Known Member
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Boulder City Nv
#3
Welcome.
//As mentioned above, remove and clean the grounds to the engine. This problem would have me removing the controller and cleaning it's mounting also.

A word of caution- only use AC Delco 60G or Bosch 80034 as they as self limiting plugs.
 

WarWagon

Well it hits on 7 of 8...
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8,609
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3,278
Location
AZ
#4
Bypassing that switch in combo with a bad ground can have the glow plugs come on at full temp and 65 MPH. This blows the glowplugs in half and impacts into pistons. We had a bad switch on ours nearly take out the engine. Don't bypass that switch.

Quick and dirty fix is getting a 1993 controller and retrofit it in. The 1993 is self contained vs. the unreliable mess your year is.

Otherwise get the flowchart for the assumed round thread in controller you have.
 

Reiter1001

Chasing rabbits
Messages
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11
Location
Pa
Thread starter #5
Thanks for the help guys but I started the truck today and it's all working I think the new controller may not be a choice part but it's working for now
 

Reiter1001

Chasing rabbits
Messages
12
Likes
11
Location
Pa
Thread starter #6
Bypassing that switch in combo with a bad ground can have the glow plugs come on at full temp and 65 MPH. This blows the glowplugs in half and impacts into pistons. We had a bad switch on ours nearly take out the engine. Don't bypass that switch.

Quick and dirty fix is getting a 1993 controller and retrofit it in. The 1993 is self contained vs. the unreliable mess your year is.

Otherwise get the flowchart for the assumed round thread in controller you have.
I'm actually putting a toggle switch in place of the head temp sensor so I can switch off the glow plug system when the engine reaches operating temp
 

Will L.

Well-Known Member
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7,746
Location
Boulder City Nv
#7
Leroydiesel.com sells a solenoid that attaches to the controller perfectly. If you are going manual instead of automated, thats your key along with those plugs I mentioned. Non regulated plugs can overheat, swell, break and destroy the engine.
 

Reiter1001

Chasing rabbits
Messages
12
Likes
11
Location
Pa
Thread starter #8
The systems all new except the glow plug temp sensor in the right head they are obsolete or at least I cant find new replacements for it I bypassed it for diagnostic purposes all I'm doing is replacing it with a toggle switch the system will still work own it's own after it warms up I'll flip the switch and shut them off for now. But the next time they fail I will switch to a manual system probably should have this time but I just purchased it and it has been sitting for years so far I had to replace the injection pump and the glow plug system but I'm still chasing demons in just about every system probably all ground issues I'm sure. Should be able to drive it by the end of the week maybe
 

WarWagon

Well it hits on 7 of 8...
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3,278
Location
AZ
#9
@Reiter1001 I see what you are doing now. IMO I would convert it to full manual with self limiting plugs, now. I do not know how modern self limiting glow plugs would handle actavation on a hot running engine in the failure mode I described for the auto system. The early 90's plugs put a hurt on the engines. So instead of Band-Aids on an unreliable system just KISS. Again its risky to mess with this system when its not working properly. Yeah full manual and move on to other things it needs...

If you want to restore it I have some of those sensors around. No idea if they work.

Simple full auto system that doesn't use that obsolete sensor is 1993 that mounts to the head and has cut out sensor built in.

@Will L. Is the relay for the round controller similar to the 1988 or so on up design? Not sure Leory's part would work with the round thread in style I think this year has.

How about some pics of this rig!?
 

WarWagon

Well it hits on 7 of 8...
Messages
8,609
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3,278
Location
AZ
#10
To be clear a bad connection to power or ground "resets" the controller. At reset it assumes cold start and cycles the plugs unless the temp cutout on the pass head says no. The temp cutout fails NBD. except if the engine is running and the controller has no way to know.
 

Reiter1001

Chasing rabbits
Messages
12
Likes
11
Location
Pa
Thread starter #12
@Reiter1001 I see what you are doing now. IMO I would convert it to full manual with self limiting plugs, now. I do not know how modern self limiting glow plugs would handle actavation on a hot running engine in the failure mode I described for the auto system. The early 90's plugs put a hurt on the engines. So instead of Band-Aids on an unreliable system just KISS. Again its risky to mess with this system when its not working properly. Yeah full manual and move on to other things it needs...

If you want to restore it I have some of those sensors around. No idea if they work.

Simple full auto system that doesn't use that obsolete sensor is 1993 that mounts to the head and has cut out sensor built in.

@Will L. Is the relay for the round controller similar to the 1988 or so on up design? Not sure Leory's part would work with the round thread in style I think this year has.

How about some pics of this rig!?
I'm goin to start a thread detailing my restoration I'll post a link to it if I can I'll post some pics here to
 

Reiter1001

Chasing rabbits
Messages
12
Likes
11
Location
Pa
Thread starter #13
@Reiter1001 I see what you are doing now. IMO I would convert it to full manual with self limiting plugs, now. I do not know how modern self limiting glow plugs would handle actavation on a hot running engine in the failure mode I described for the auto system. The early 90's plugs put a hurt on the engines. So instead of Band-Aids on an unreliable system just KISS. Again its risky to mess with this system when its not working properly. Yeah full manual and move on to other things it needs...

If you want to restore it I have some of those sensors around. No idea if they work.

Simple full auto system that doesn't use that obsolete sensor is 1993 that mounts to the head and has cut out sensor built in.

@Will L. Is the relay for the round controller similar to the 1988 or so on up design? Not sure Leory's part would work with the round thread in style I think this year has.

How about some pics of this rig!?
Here the link to the restore thread
https://www.thetruckstop.us/forum/threads/84-c30-crew-cab.47680/
 
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