All,
While doing my first rear diff fluid change this weekend I had the misfortune of breaking on of my cover bolts. Yes I was using a Torque Wrench and yes it was correct. I would like to offer a warning to Check your bolts for cracks! I am certain this bolt was cracked from the factory.

I “snugged” the bolts with a regular wrench then went back and torqued them to 15 ft-lbs and then to 25 ft-lbs. When I went to torque this particular bolt it sheared off almost instantly (before the 15 ft-lbs which is half the mfg spec.). For those of you who have broken a bolt, when have you ever broken one in the center of the bolt and not at the head (when the head is touching)? Also when you shear a bolt, the sheared section is shiny. In this case the bolt only had a small shiny portion the rest was black like the coating on the bolt. So I recommend that you all check your bolts to make sure that you don’t have a cracked one.

Sorry about the Rant !!!

Please feel free to add your opinions on this topic.

Now I have the joy of removing the broken bolt or pay the dealer $200.

 

I had the same thing happen to 3 of my rear cover bolts. I posted this awhile back and had nothing but replies of it must have been incorrect torque or that oil had been on the threads. I did have some blue loctite on the threads but no oil and my torque wrench is calibrated once every year by Snap-On. I agree that there is either a bad batch of bolts that have poor tensile strength or that they are cracked or overtorqued from the factory. Just out of curiosity what was the build date on yours...mine was Jan 17.

Paying the dealer $200? Not sure why this would be? As far as removing the bolt...it is fairly easy once the head has snapped off as there is no more tension on it. Just drill a hole and use an easy out. I was able to get mine out just with a reverse drill bit...didn't even have to use the easy out.

Glad to know that it isn't just me!

 

CRXsi, bolts !!! That is out of control. My truck was built in July I think.

I was not using any lubricant other then some rear diff fluid. I know there was nothing in the treads as they went completely snug with just finger tight. Luckily it is not leaking at the moment so I am going get back to the shop (an hour away) this weekend and drill it out. We have the left handed drill and the easy-outs. three

 

Yup...3! The threads in the diff housing were clean and dry. Like I said...since I'm ****...I used blue loctite on the threads (not enough to hydro lock it, just a little) and used a 3/8 torque wrench calibrated for my work once per year. I did like you...steps. the first once started to break at 15ft-lbs. I backed it out and replaced it. The other 2 broke while going to the final torque. I was able to get them both out with a reverse drill bit. The front diff cover was OK with no issues. I will likely just replace all the bolts when the next diff service is due as a precaution.

Like I said...glad to know it wasn't just me. It would be interesting to follow a trend and see if it is common on 04.5 trucks built within a certain period. Might just be the guy on the assy line at that time was a gorilla and had been overtightening all of them.

 

I read several threads about broken cover bolts, but since I got through my 1st axle fluid change OK, I figured I was out of the woods... wrong.

When I was changing them again around 30k, I broke one off in my front differential cover. I was using a torque wrench, and it never came close to reaching specified torque. I think it broke right at the head.

Anyhow, the reverse drill didn't back it out, but it came out very easily with a spiral flute type extractor.

The bolts have a kind of brittle feel.

Next time I think I will see if I can find a complete set of replacement bolts.

 

The first time I pulled the cover I noticed the bolts were installed with red loctite. If I put them back as they were I surely would have broken them. I spent about 30 minutes wire brushing all the crap out of the threads and had no trouble installing and torquing them.

Pete

 

You'll get a more accurate torque reading if the threads are lubricated prior to installation.

 

So did I.

Mine had stuff on the threads that appeared to be form-a-gasket or something similar, which I did wire brush off. The threads were clean, but one broke anyway.

 

I use an air ratchet to remove and install them, never broke one

 

I'm thinking of buying some allen head screws to replace the factory ones. I don't want to press my luck that next time make break one. They look cool.
The last time I change the oil I sucked it out. The first time I looked inside everything was clean. The dealer told me they just suck it out.

Pete

 

Dc has the wrong torque specs. for those bolts from what I've read here. Their are only a couple things I torque on a vehicle, and that cover is not one of them. How many shops you ever see torque rim bolts, next to none, but that's one thing I do torque. I also bet you won't find one dealer that will torque that cover back on either, but they might say they did. I know this because I was a GM tech . for about 12yrs., and saw this crap every day. O'h the lies we would tell
the customers, I hope I go to heaven,the man made me do it.

 

I use a cordless impact to install them. Never broken one and no leaks. Takes a "mechanics feel" not to overdue it.

 

Same here................

 

I am glad not every one had the same problems I did. Like I said it was a bad bolt from the factory and it was probably a fluke. I just wanted to make every one aware of the problem in hopes that I can prevent some one else from having it. I know that these bolts are strong and should not break that is why you can get away with tightening them with an impact wrench.