First LBZ problem rears it's ugly head!!!

[madmatt]

Got a call from my old dealership the other day to come and check out this LBZ they just got in. Had two miles on it, an SES light and a awefull rattle/knock. they had checked the codes and found a P0??? something or other for the glow plug circuit. They went through their diag and found the #2 plug had blown a tip.....into the cylinder :eek: Quick call to GM got me the dreaded "another one???" answer. It seems the glow plugs are staying on to long and melting the tips off and getting real nasty in the cylinders. Got the engine out and it's getting a new piston and rod, head, injector, bearings, and of course a set of plugs. I wouldn't get alarmed and start trading'em as GM is aware and is addressing the problem. They've sold a bunch of LBZs and failures have happened but appear to be limited.

[rjschoolcraft]

What glow plugs are they using? We in the 6.5 world have found self regulating plugs that can stay on indefinitely. Maybe I'm just dumb, but this seems obvious... Reduced compression. Needs longer glow for cold starts. Need to use a self regulating plug. We've been modifying our glow circuits for years for longer glows on the 6.5.

[gmmerlin]

Originally posted by madmatt:
Got a call from my old dealership the other day to come and check out this LBZ they just got in. Had two miles on it, an SES light and a awefull rattle/knock. they had checked the codes and found a P0??? something or other for the glow plug circuit. They went through their diag and found the #2 plug had blown a tip.....into the cylinder :eek: Quick call to GM got me the dreaded "another one???" answer. It seems the glow plugs are staying on to long and melting the tips off and getting real nasty in the cylinders. Got the engine out and it's getting a new piston and rod, head, injector, bearings, and of course a set of plugs. I wouldn't get alarmed and start trading'em as GM is aware and is addressing the problem. They've sold a bunch of LBZs and failures have happened but appear to be limited. They need to check the wiring to the GPCM! Especially the large battery feed wire. These can loosen at the connector and cause the GPCM to power up the glow plugs..there is a PI about that for the LLY.
The LLY and LBZ are the same engine

[madmatt]

GM didn't have a fix yet. Said it was most likely going to be a programming change and he acted as if it was containted to a certain few vehicles. it was the first I had heard of it. Can't check any wiring now the engine is on the ground at GMs request. They never mentioned a bulletin nor could I find one.

[rjschoolcraft]

Originally posted by ronniejoe:
What glow plugs are they using? We in the 6.5 world have found self regulating plugs that can stay on indefinitely. Maybe I'm just dumb, but this seems obvious... Reduced compression. Needs longer glow for cold starts. Need to use a self regulating plug. We've been modifying our glow circuits for years for longer glows on the 6.5. madmatt,

Any comment?

[madmatt]

I'm not real famialiar w/ the 6.5 and their glow plug systems so I can't really compare but the way I understand the LBZs operate w/ just the glow plug controller turning the plugs on and off as commanded by the ECM. No self regulating plugs that I know of. I left the dealership before i got to play w/ the LBZ very much.

[gmmerlin]

Originally posted by ronniejoe:
What glow plugs are they using? We in the 6.5 world have found self regulating plugs that can stay on indefinitely. Maybe I'm just dumb, but this seems obvious... Reduced compression. Needs longer glow for cold starts. Need to use a self regulating plug. We've been modifying our glow circuits for years for longer glows on the 6.5. Since 2004 with the LLY, the DMax has used a 4.7volt fast heat glowplug system..these glow plugs heat up to 1900 degrees F in 2 seconds.
The LLY and LBZ use the same system in 2006. One of the differences is the 06 MY engines have a new thread location for the GPs.
the GPCM controls and monitors the glow plugs.
This is one of the reasons the DMax has such a short cold start wait.

If the large 12 battery feed wire is loose, this will cause a voltage drop and will cause the GPCM to turn on the glowplugs.

[markrinker]

I want to check my truck today. Where is this wire, what color is it, and what do I look for?