Broken Duramax Glow Plug #8
I know this network likes to focus on hard to diagnose issues and complex electrical concerns, but sometimes we face good old fashioned mechanical issues. I will start off by saying I personally own the vehicle in this discussion. The other day my wife let me know the MIL was illuminated on the truck and the glow plug light would not go out. It was a 90+ degree day so I suspected I had a glow plug issue. After scanning and diagnosing the concern, I found the #8 glow plug had come to the end of it's useful life.
The #8 glow plug is on the driver side of the truck and it is cantered towards the bulkhead (firewall). If you are familiar with these trucks, you will recall the engine is tucked neatly under the cowl. So needless to say, this glow plug is NOT in a easy to service location. After removing the inner fender liner, I blasted the glow plug with penetrating oil and then my favorite concoction of ATF and acetone. I attempted to remove the glow plug using a universal joint and a 24" extension without success. I continued to soak down the glow plug, heat cycle the engine, etc. Unfortunately, the glow plug was seized in the cylinder head and head of the glow plug eventually snapped off.
I began the mad search to see if anyone had any success removing a broken #8 glow plug, and almost every credible resource I looked at stated the cylinder head needs to come off. Being determined to find a better way, I found out that a glow plug extractor kit exists. The price of the kit ranged from $40 to $350. All of the kits looked exactly the same (b…d on the pictures). I rolled the dice and purch…d the $40 kit from my favorite online retailer. 2 days later, I had the kit in hand and ready to go.
Unfortunately, there was no easy way to access the glow plug at the correct angle. The cab was blocking my 90 degree drill and I was dead in the water again. After sleeping on the situation, I recalled how I used to have to lift the body off the early GM S10/S15 trucks to access the top 2 transmission bolts. I called up a buddy who is also a tech at a local Ford dealership and we proceeded to jack the crew cab up off the frame. The only things we needed to do was remove the master cylinder from the hydro-booster, separate the intermediate steering shaft, and disconnect the parking brake cable. We lifted the body high enough to slip a 4x4 block between the frame and body mounts. This gave us enough clearance to drill out the glow plug. The extractor kit worked flawlessly and it was the best $40 I had spent in a long time. The only downer of the entire process was I ended up installing a tread repair coil to the head. My drilling skills we not absolutely perfect. I would have likely been able to do the repair without the thread repair kit had I lifted the body high enough the first time.
Ultimately, the entire job cost me $150 in parts and about 10 hours of labor. Obviously, in the future I could do this job in 2-3 hours at very most now I know the tricks. I wanted to share my story in an effort to help someone else in the same situation. 2-3 hours is much better than pulling the head. Feel free to reach out to me if you have specific questions.
I have had good luck getting those engines warm before attempting to remove the glow plugs. Have not broken one since I started warming up the engine first
That tool looks prettty handy though. I will purchase one just in case. For 40 bucks it’s worth it to have in the arsenal.
Thanks for sharing.
There is no feeling like when something this drastic happens to your own vehicle. Great job seeing your way through.
Let me start off by saying I don’t work on diesel engines if I can help it. Maybe 1 a year and i don’t do anything in-depth at that. Yesterday I had my neighbors truck in for a MIL. Glow plug circuit code P0676. Number six had an open glow plug. I replaced all 4 on that bank. I have heard these glow plugs like to break but I haven’t had that happen to me the 3 times in my career I have touched glow plugs on these engines.
I did replace number 8 and can easily see how getting a tool in there could be difficult.
Thanks for posting this tip.
I should also add that this truck spent 5 years living in the Michigan winter salt and 2 years in the of Virginia winter brine. This truck also has 150K on the odometer. I feel like I take good care of the truck, but that salt/brine are a serious killer. I used to tell my students to ALWAYS pull ALL of the glow plugs and apply anti-seize. #8 is tough and #4 require the separation of the intermediate shaft. Neither of those things I did... So the moral of the story is an ounce of prevention is worth more than a pound of cure.
Number 4 came out without the shaft removal. I couldn’t get a socket on an extension on it. I used just a socket on a ratchet behind the steering shaft to break it loose and then unscrewed it. I would think that the shaft would have to come out to use the extractor tool though.
The shaft is held together with 1 bolt. Remove the bolt and separate the shaft. I did not know that at the time or I would have done that long ago. Thankfully, #4 came out very easy. Great discussion and hopefully some good tips for others in the future.
Hi Kevin. FWIW, if you mention your tip to anyone with later model Duramax engines, make sure that they also know that the glow plugs are ceramic and are remove, discard and replace..... It can get expensive
Thanks Martin, that is a great tip. I was not aware that starting in 2017 the glow plugs are one and done. I looked up in SI and it clearly states the glow plugs, if removed, must be replaced. I priced them out, and they are not too hateful, but none the less, it would be a pricey adventure if you chose to go down that road. Thanks again!
That kit is very similar to one I have and have used more than I care to remember on Mercedes. I know the feeling of laying in bed pondering over what the next move is to avoid head removal.
Good job! Did you have to use a reamer or some kind of drill bit to remove carbon buildup from the small diameter section that goes inside cylinder? We had the misfortune on one where the glow plug set a code, we removed it (didn't break) installed new one, and the code was still there. Recheck work, remove new glow plug and it now comes out without the small tip attached, only the small diameter section stayed in the head. Daaaaannnnngggggg! After much discussion we removed both cylinder heads and head them all redone with valve grinding and everything, client was kinda keen to have all that done luckily. We looked at tool kits for quite awhile too but were just not sure if any of them would be up to the task that we were now in neck deep..? Does anyone know if there is anything available which would have helped us out in this case?
So the tip broke off upon installation, just with shear twisting force. Then after it was broken it likely was forced even tighter in with press action due to threaded portion of plug not being tight yet. Apparently with long time use the old glow plugs will attain a slightly smaller diameter from all the heat cycles. This allows carbon to build up right against the tip. Then when a slightly larger (new) plug is installed it starts in then wedges tightly enough that it eventually will twist right off. Noticed later there is tsb regarding the possibility of this happening and GM has a specially made small diameter reamer that can reach way inside there to cut loose the carbon.
That whole job was more excitement then I care to experience too frequently.
Hi Maynard, thanks for reading. I did not use a reamer on the glow plug hole. I know about the cleaning kit that is required when doing injector service, but I was not aware of a reamer that is used with the glow plugs. From what I have read, it looks like the reamer is only used with L5P Duramax. Regardless, it sounds like I need to sit in on some Duramax update training.
As for broken tips in the cylinder head, I am not aware of any procedure to extract the tips. If sucked into the cylinder, the tip will destroy the piston, valves, and possibly the cylinder head. I am glad you had an understanding customer. That is usually not the c…. My biggest fear through this entire adventure was pulling the head. I have a drive-on lift at home, but do not have access to a side post lift. I know it is possible to pull the head without pulling the cab, but I also know trying to pull the heads on a 12 y/o truck that lived in harsh conditions is a recipe for disaster (and many bloody knuckles).
We have had good success pulling the injector out and blowing compressed air to blow broken tips out if the cranking compression doesn't work, which in most cases it does.