Fun With Glow Plugs

joe_ · **Posted:** Sat Jun 18, 2016 3:02 pm

I'm in the middle of a timing belt/water pump/rockers/studs job, and I figured I'd might as well get the glow plugs replaced while the intake/valve cover is off. Unfortunately, I've run into a few problems.

Problem #1:
I'm noticing an orange powdery substance on the tips of the glow plugs. Is this normal, or is it dried coolant? I haven't driven this Jeep much since I bought it (only about 300 miles) and while I haven't noticed any signs of a head gasket leak, I don't know for sure that it doesn't leak.

Problem #2:
Glow plug #2 took a lot of torque to unscrew - enough that I was starting to consider swapping out the 3/8" ratchet for a 1/2". I remember someone saying they had overtorqued their outer head studs, slightly crushing the glow plug holes. I had torqued the outer studs to 120 ft/lbs per the instructions, but I loosened the nut on the closest stud just in case (removal torque was 98 ft/lbs, which was about the average amount the original TTY bolts required). That didn't really affect the glow plug at all; removing it stil took way more torque than it should have. Once removed, there was a pretty good amount of aluminum in the threads (center plug):

Installing the new one again required way more torque than it should have, and it wouldn't go in as far as the others. I pulled it back out, and it had some aluminum in its threads as well. Obviously the threads are pretty messed up and probably can't be trusted to hold the glow plug in under combustion pressure. What's the best way to fix this? Helicoil?

Problem #3:
Removal of glow plug #3 started off ok, but after about a half turn, it got real tight like #2. A couple turns later, and there was a snapping noise and the top of the glowplug got wobbly. The hex section snapped off of the threaded section, but was still held on by the inner wire. That clearly wasn't going to be very helpful, so I just broke it off the rest of the way. Has this ever happened to anyone else?

Does anyone have any idea what would cause the threads to bind like they did on plugs #2 and #3? These are the old style ceramic plugs, but they aren't originals as the date code is 04-10-07 on them. Should anti-sieze have been used on the threads or something? Any suggestions for removing the broken one, and repairing the threads? At this point I'm kind of tempted to buy a new head, but for the price, I'd rather try to fix this one first.

Thanks in advance!

- Joe

rankom · **Posted:** Sat Jun 18, 2016 6:28 pm

well i think you did ok at least you did not drop a valve , so you are in the GREEN ZONE , just remove your cylinder head and send it to the machine shop , they will do all the work , and you will install it in the back . it is just that easy .

WWDiesel · **Posted:** Sat Jun 18, 2016 9:35 pm

What a bummer, it has broke off and one of the few options is to remove head and take to a machine shop and let them drill it out and possibly re thread and install a helicoil. If you go this route or purchase a new head, be sure and use some anti-seize on the threads of the new glow plugs... :shock:

Got me scared to even touch mine now.... :roll:

jws84_02 · **Posted:** Sun Jun 19, 2016 12:03 am

Is it possible to run a tap down #2 at all? I can't really tell how far gone it is. As for #3, they make a glow plug removal kit for instances like that and it is somewhat common. You shouldn't even have to remove the head if you give yourself room to work

joe_ · **Posted:** Sun Jun 19, 2016 1:40 am

I'll check about the glow plug removal kit, but at this point even just dropping it off at a machine shop doesn't sound like a terribly bad option. Another thing I thought about is just running one of those spiral screw extractors down the broken plug, assuming I can get the remains of that center wire out of the way (it's fairly heavy gauge and runs right down the center of the glow plug).

If I'm running a tap down the #2 glow plug hole, I'm probably going to want to have the head off so I'm not dropping shavings in the cylinder, right? In that case, maybe I should just take it to a machine shop. Pulling the head won't be much work at all; I just installed the ARP studs and haven't put the valve cover back on yet.

jws84_02 · **Posted:** Sun Jun 19, 2016 8:20 am

Yeah good point. If you did leave it on the block you definitely should coat the tap in grease.

joe_ · **Posted:** Fri Jun 24, 2016 7:24 pm

I've got the head pulled and dropped it off eariler today to be worked on. The first place took a look at the broken glowplug and wouldn't touch it, but after talking to a few different people, I was referred to a shop that was willing to give it a try. I guess a local dealer drops off Isuzu heads to him with the same problem, and he said the majority if them are beyond saving. But he said many of the bad ones are due to people trying to drill it themselves and screwing things up worse.

I was thinking whoever had installed these had overtorqued them and damaged the threads, but the guy at the shop said this is normally just caused by the interaction between the aluminum head and steel plug causing corrosion (accelerated by the road salt around here). He definitely wasn't a fan of the Bosch plugs as the threaded area is bare steel as opposed to other brands, which I guess have a coating to reduce/prevent corrosion. Sounds like a thin coat of anti-sieze is a really good idea on these, especially for those driving in the rust belt.

joe_ · **Posted:** Fri Jun 24, 2016 7:29 pm

joe_ wrote:

These are the old style ceramic plugs, but they aren't originals as the date code is 04-10-07 on them.

Reading that again, I take that back; they just might be originals. I was reading it as April-10-2007 but it's probably 2004-October-07, especially considering Bosch is Europe-based.

joe_ · **Posted:** Fri Jun 24, 2016 7:42 pm

WWDiesel wrote:

Got me scared to even touch mine now.... :roll:

I wouldn't be too worried about corrosion in Georgia since you guys don't have to deal with road salt all winter. Just go slow and take your time. To be honest I'm sure part of the reason that one broke is because I was getting tired and frustrated, and I think I was pulling on the ratchet handle rather than turning it ... I don't think I was supporting the glow plug end of the ratchet with my other hand at all, so it was up to the glowplug to convert that pulling force to a twisting force. Pretty stupid in hindsight.

Ceearedeedriver · **Joined:** Fri May 06, 2016 8:44 pm **Posts:** 177

joe_ wrote:

WWDiesel wrote:

Got me scared to even touch mine now.... :roll:

I wouldn't be too worried about corrosion in Georgia since you guys don't have to deal with road salt all winter. Just go slow and take your time.

This is the key. Soak well in advance with PB blaster or equivalent. The last one I did had been in there 9 years and took most of the day to get out. If it feels too stiff then no more than 1/4 turn, spray some more penetrant, back it in and out a few times leave it for an hour and repeat. It will eventually come but just don't force them or you'll break them.

WWDiesel · **Posted:** Fri Jun 24, 2016 9:37 pm

Thanks for the encouragement; my glow plug day is coming and I got plenty of PB Blaster along with several other high zoot penetrants including the new CRC Freeze Off type.... :wink:

http://crcindustries.com/auto/?s=05002

Fun With Glow Plugs

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