I had a #6 glow plug go bad on my 2004 LLY (P0676 DTC Code). After reading lots of threads about horror stories of twisted off glow plugs, I decided to do some research. I spoke with a friend who is a tech at a GM dealership and he confirmed that they twist off in the head "all the time." He described a method of getting them out with drill bits and easy outs. This did not sound appealing to me. Note that my truck has 230,000 miles on it and I am not the original owner. I assumed that these were original glow plugs but I can't say for sure.
Here is what I did and it worked PERFECTLY. I sprayed them all down with Kroil, which is supposed to be about the best penetrating oil you can buy. Anyone that has used it says it is many times better than PB Blaster. I can't verify this, because this is the first time I used it.
I sprayed all four driver's side glow plugs with the Kroil (2,4,6,8). Since #6 was the culprit and also the easiest to get to, I went after it first. I allowed the Kroil to soak for about an hour and then tried it with a socket and ratchet. The glow plug wouldn't budge. I was sure it would twist off if I put any more nuts behind it. Next I went after my 1/2" drive cordless Ridgid impact driver. I impacted it lightly until it spun right out. I couldn't believe how great this worked! I decided to replace the other 3 glow plugs on the driver's side since I already had the wheel well out. They all came right out as well with the cordless impact and an extension. I installed the new ones with some anti-seize so that next time it will be even easier. I would recommend to anyone to use the electric impact method. The key is to start very light and work your way into it. If you go after it full-throttle you will likely break one. I got this idea from an internet search where a British company sells a low-powered air impact for this purpose. No one in the US sells such a beast. A cordless impact and some finesse is all you need! Keep in mind for the driver's side glow plugs you will have to disassemble the down pipe and steering shaft to get access to all of the glow plugs. They are both really easy to get out of the way, adding only about 5 minutes to the whole job.
I am going to wait to do the passenger side glow plugs until one of them goes bad and then I will do all four of them at the same time as well. I can't believe no one has posted this idea before because it works so well (at least if they have posted it I couldn't find it in any searches). Share with your friends!
Here is what I did and it worked PERFECTLY. I sprayed them all down with Kroil, which is supposed to be about the best penetrating oil you can buy. Anyone that has used it says it is many times better than PB Blaster. I can't verify this, because this is the first time I used it.
I sprayed all four driver's side glow plugs with the Kroil (2,4,6,8). Since #6 was the culprit and also the easiest to get to, I went after it first. I allowed the Kroil to soak for about an hour and then tried it with a socket and ratchet. The glow plug wouldn't budge. I was sure it would twist off if I put any more nuts behind it. Next I went after my 1/2" drive cordless Ridgid impact driver. I impacted it lightly until it spun right out. I couldn't believe how great this worked! I decided to replace the other 3 glow plugs on the driver's side since I already had the wheel well out. They all came right out as well with the cordless impact and an extension. I installed the new ones with some anti-seize so that next time it will be even easier. I would recommend to anyone to use the electric impact method. The key is to start very light and work your way into it. If you go after it full-throttle you will likely break one. I got this idea from an internet search where a British company sells a low-powered air impact for this purpose. No one in the US sells such a beast. A cordless impact and some finesse is all you need! Keep in mind for the driver's side glow plugs you will have to disassemble the down pipe and steering shaft to get access to all of the glow plugs. They are both really easy to get out of the way, adding only about 5 minutes to the whole job.
I am going to wait to do the passenger side glow plugs until one of them goes bad and then I will do all four of them at the same time as well. I can't believe no one has posted this idea before because it works so well (at least if they have posted it I couldn't find it in any searches). Share with your friends!