Good Experience Changing the Glow Plugs and Relay

Well I knew it would probably be a good idea to go ahead and change out my glow plugs and glow plug relay. The truck started great after it warmed up but was hard starting in the morning. Sometimes I had to crank and crank the truck. Let off, recycle the ignition, and then crank again before it would start. I went to O'Reilly and got the AC Delco 60G glow plugs and the BWD GPR1 glow plug relay.

All the old plugs came out really easy with none of them being swollen up. I did find out the second glow plug from the front on the passenger side was not hooked up. The glow plug was in there but the wire was not connected. I went ahead and pulled out all the old ones, shaved down the heads on the AC Delco plugs, and installed them.

The glow plug relay gave me some trouble. For one the BWD relay does not mount the same way that the one on there did. It needed much longer screws which did not come with the kit. So to get it mounted up so I could get the truck to the store I zip tied it on snugly. It's less than two miles to the Home Depot where I can get the screws so I'm sure it will be fine. I just ran the zip ties through the mountine holes and secured it to the plate on the firewall.

After I hooked the batteries back up I got in to see how it started. I got home at around 5:30 pm and this was about 2:30 am so it was plenty cool. No drag at all and the truck started right up. I barely had to crank it at all. So all in all I would say it went well. As soon as I attach those screws to more securely mount the relay it should be perfect!

I need to do that to my M1008. It cranks a long time in weather below about 40. I hope mine goes that easy.

the hardest one to access when I did mine was the pass rear, I reached thru the wheel well with about a 24'' extension all the others were uneventfull.

As soon as I attach those screws to more securely mount the relay it should be perfect!

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That's the toughest act, really! These zip-tie jobs tend to stay!

Cheers,
Mark

Yeah that rear passenger plug was a pain. I used deep socket and a ratchet. I just reached in under the battery tray and felt my way through it. Of course I have long arms and I could just barely reach it so if I'm sure most people would have to get a little more inventive.

I just changed mine out yesterday. I started on the driver side and worked my way around finishing on the rear pass. side. Wouldn't you know it, that was the one swollen one that won't come out.

I'm doing research now to figure out a course of action. Switching out my other 7 fixed my starting woes however, so I'm happy about that for now.

ClockworkSkin said:

I just changed mine out yesterday. I started on the driver side and worked my way around finishing on the rear pass. side. Wouldn't you know it, that was the one swollen one that won't come out.

I'm doing research now to figure out a course of action. Switching out my other 7 fixed my starting woes however, so I'm happy about that for now.

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If your glow plug system is "stock"(24v) , and you have one bad glow plug, you are at great risk to damage the other 7 new glow plugs. Don't start your truck again, until you replace that last one!

If you temporarily resupply the glow plug relay with 12V+ from the front battery, you can start it without fear of burning out your new glow plugs.

There are a couple of tools availible that help with removal of swollen glow plugs. I have also had luck removing them, just by using a small set of visegrips on the gp, and running the engine warmed up good, then unscrew the gp and let it sit in the hole with the swollen end plugging the hole, with one hand I push in against the visegrips and let the explosion of the cylinder, pop it out(runnng the engine). The key is to get the gp good and hot and let it "pop" out several times. It will sound like your shooting a shotgun, if done right! Yes this is slightly dangerous, wear gloves and eye protection.

Good luck!

Doghead. I think you're right. It's been a week and I'm having starting problems again. I'm very green when it comes to mechanic work and the learning curve has not been friendly to me.

I'm in the process now of pulling all new plugs and testing them. I'm afriad that I may have made a mess for myself.

Once I figure out which plug is good and which is bad, I want to test the relay. Is the voltage at the the orange wire what I'm looking for? It clicks and I have 24v at the red wire, however the voltage at the orange wire spikes and I get a reading as high as 15v. I'm sort of confused as to what this should be. It's it's higher than 12v does that mean that GPR is bad, or the resistor?

Yep, I got 7 of them out. All bad. I'm going to order a new set tonight. Before I put them in, I would like to know what I need to check to make sure that I don't go down this road again. I've been reading the forums, and the TMs and thoroughly confused. As always, thank you to everyone for sharing their knowledge.

I used the Wellman 070's from INDUSA dist, did a bypass of the resistors and installed a new GPR. If you are going to be slave cabled or slave cable someone else you should have the resistors. I figured I will use jumper cable(s) I have absolutely no use for a slave cable, and why risk more than 12v coming to the GPR then to my GP's! Doghead says a bad resistor can burn out plugs by allowing to many volts, also if you have a bad connection on even just one plug (OR having one not connected at all) this can destroy a set of GP's real fast. In the future I am connecting a standard size 1/4 inch female connector on the GP wires and using Wellman 050's. <--- these are cheaper than AC 60G's preference is all. If you remove the Resistors: disconnect the lead wire to resistors at 24 buss block, remove cover to resistors, take the wire off side closest to GPR, drill out eyelet slightly, remove nut on diamond shaped 12v block (next to GPR) slide wire/eyelet onto bolt, install that nut you removed. DONE yes you draw the load of engaging gp's from front battery, if your so inclined rotate your batteries ever so often (6mo.) I drive enough to charge battery(ies) I'll have batteries tested every so often at ex. AAP to see If I will ever need to rotate batteries.

what is this resistor you speak of and where do i get a new one... just in case... might as well just go ahead and replace it

The resistor is the big black box looking thing attached to the firewall directly behind the air cleaner. It is only available through the military supply system or surplus unless you get a used one.

It is not always a failing resistor that causes the glow plug failure, it is failing glow plugs combined with the design of the resistor that causes the problem.

The resistor is designed to work with the resistance of the glow plugs to pull the voltage down to 14 or so volts. If one glow plug's resistance is missing the other plugs get more voltage. This causes them to burn out and lowers the resistance more increasing voltage, wash rinse repeat until all 8 plugs are dead.

At this point, 24V is now being supplied to the glow plugs, and by design, the voltage sense wire to the glow plug controller card. Prolonged application of 24V to the controller card causes a transistor to break down and fail, burning out the card.

Later,
Joe

DO THE BYPASS AND YOU WILL GET 12 VOLTS TO 12 ZOLT GLOW PLUGS