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SStar · 03-01-2014, 09:15 AM

My tow vehicle is a 2007 Yukon, 6.0 2500 XL. About all I use it for is to tow the Airstream, and have been quite satisfied with it in the time that I have had it. But now the problem, I recently noticed a ticking noise when starting it cold, which went away as it warmed up.
I have the extended warranty so I took it back to the GM dealer where I bought it. It was diagnosed as a broken exhaust manifold bolt that was allowing an exhaust leak. The warranty rep was contacted to decide the repairs. The dealer wanted to install a new head, the warranty folks want to remove the head and send it to a machine shop to extract the bolt, which we will go with.
Neither the dealership mechanics or the warranty folks seem to be very familiar with this problem or the solution. In talking with a couple of local independent mechanics, they both tell me this is a very common problem with any GM V-8s, including diesels, that was built in the past fifteen years. A little research on-line tends to bear this out, with some engines having several broken bolts.
My question, I know there are a lot of GM TVs in use by forum members, has anyone had this problem? what was the solution? Does anyone have any info concerning a recall? I would appreciate any and all input.
As a final note, the local mechs both recommended that any GM vehicle be checked for broken bolts. Thanks!

perryg114 · 03-01-2014, 09:44 AM

It is common on many vehicles. The practice is usually to drill out the old stud and put a new one in. Most of the time, they can be removed the vise grips if the stud is above the surface or they can be drilled out. It is not fun to do, but it can be done. What you don't want to do is break off an easy out off in the stud because that will be too hard to drill out. I would replace the studs with stainless steel ones that are less likely to crack. If the leak goes on for a long time, it will pit and erode the gasket surface and worst case is a new head in that case.

To drill out a stud, you start with a small bit and drill into the stud and gradually go to a bigger drill bit. When you get close to the threads, most of the time, it will break loose without damaging the threads in the head. Worse case is a heli-coil to fix the threads. Sometimes you get lucky and the stud is loose and an easy out will work fine. All too often, the stud is corroded in there and you will just break off the easy out in the stud. It is best to replace all the studs at the same time, especially if the head has to be removed.

Perry

SStar · 03-01-2014, 12:48 PM

Thanks for your input, seems simple enough if everything works as it should. I never realized it is a fairly common situation for the bolts to break. I have owned numerous GM vehicles and never had the problem, or just didn't know it. If i ever trade for another used GM you can bet I will check to see if any of the bolts are broken. In all actuality this may have been broken when i I got it, I have only put about 12k miles on it.

**GCinSC2** · 03-01-2014, 01:09 PM

I have not had to deal with a lot of broken bolts, some but not too often. I did run into a NASTY situation a while back during a transmission R&R. I broke 3 bolts clean off on the transaxle mount, U G L Y.

The bolts went into aluminum and had a healthy "patch" of locking compound on them. Machining would have been pretty rough. Now what. Rust wasn't the real issue it was that locking compound.

Fortunately enough of the bolt was still sticking out that we were able to put a nut on the broken bolt and CAREFULLY weld it on to the broken bolt. This gave us a new surface for the wrench but it really helped by melting the locking compound bond of the bolt to transmission case. Yes, we were real careful about the location of the ground clamp.

walt c · 03-01-2014, 03:57 PM

SStar,
I learned a trick from my dad many years ago,and it works! Stick a washer over the broken stud or bolt and weld them together thru the hole in the washer. The broken bolt/stud can them easily be removed either while its still hot or waiting until its cold. The process apparently loosens the stud/bolt by running electric current thru it,not the heat.....walt...tulsa,ok

overlander63 · 03-01-2014, 04:47 PM

Depending on which bolt has broken, I simply drilled the center of the bolt and unscrewed it using a screw extractor. They really do work, though it would be best to completely remove the manifold for better access.

Jim Foster · 03-01-2014, 05:22 PM

Some extractor sets come with short, left hand turn drill bits. Sometimes when drilling out the broken stud, if it is not too tight, it will unscrew while the hole is being drilled using a left turn bit. I sold such sets and bits when I was a SnapOn tool dealer and have seen studs come out as the hole was being drilled. Sometimes you get lucky.

SStar · 03-01-2014, 05:56 PM

Great info, sounds like it is coming from real hands on experience. I just checked my daily driver, a 1/2 ton silverado. All of the manifold bolts are in place. Looks like it could be a pure pain to work on especially with drills and welders. Good thing I have mechanics for friends! I suppose the welding would be easiest with a wire welder.

overlander63 · 03-01-2014, 06:02 PM

I probably should mention I have a 90 degree drill which makes it a lot easier to get in the tight spots to drill out those studs. The drill is really handy, but not cheap. In some cases, by the time you by all the special tools to do the job, you could almost pay somebody else to do it.

gandttimes · 03-01-2014, 06:37 PM

I wonder how many of us went out and checked the driver's side rear exhaust manifold bolt of their GM 6L while holding their breath?
I know I did. Mine was OK. Whew!
George

overlander63 · 03-01-2014, 07:18 PM

Quote:

Originally Posted by gmeikle

I wonder how many of us went out and checked the driver's side rear exhaust manifold bolt of their GM 6L while holding their breath?
I know I did. Mine was OK. Whew!
George

While it's not uncommon, it's not something that happens often.

Jim Foster · 03-02-2014, 12:16 AM

Quote:

Originally Posted by overlander63

I probably should mention I have a 90 degree drill which makes it a lot easier to get in the tight spots to drill out those studs. The drill is really handy, but not cheap. In some cases, by the time you by all the special tools to do the job, you could almost pay somebody else to do it.

Funny, I have always looked at it the other way around. It may cost nearly as much to buy the tools as to have the work done by someone else, but you then have the tools. Most tools are good for more than that one task.
Once I bought a wire feed welder to use while building our Street Rod, thinking that I would sell it when the job was finished. Well, that was 22 years ago. I still have the welder and now wonder how I ever got along without it.

dznf0g · 03-02-2014, 06:11 AM

Jim, I have always done the same thing. Buy the tools, do it the way I want it done, and I'll have the tool for the next time. However, I'm trying to recognize age and accept aging gracefully. I don't get on the house roof anymore...well not much. balance isn't what it once was.

SStar · 03-07-2014, 08:57 AM

I got my Yukon back from the dealer yesterday, everything looks good, I checked the right side and all was intact. and The repair to the left side was more extensive than was first thought. The head was removed and sent to a machine shop to extract the broken bolt. The exhaust manifold, heat shield, manifold gaskets, head and valve cover gaskets were replaced. Several hours labor was incurred. I was lucky, my deductible on the warranty was $100.00, the dealer is working with the warranty company for the balance. I was highly impressed with the way that the dealer handled the situation.
After talking with the dealer and several independent mechanics, I would highly recommend checking your vehicles, especially the V8 GMs for broken manifold bolts on a regular basis. If you catch it early it might be a simple repair to extract and replace the bolt before it develops into an exhaust leak.
If you have a vehicle that is going out of warranty soon it would be advisable to give it a good look over for any problems that need attention.

Jammer · 03-07-2014, 10:40 AM

Broken exhaust manifold studs are a common problem on any engine. I've had a couple of them replaced on my pickup, and fixed some on an old 1968 tandem-axle dump truck, and on tractors. Also happens on sedans. Not unique to GM by any means.

It is rare that the head has to be removed for such repairs, though it does happen.

perryg114 · 03-07-2014, 11:23 AM

Did they replace all of the studs/bolts? If they put the old ones back in you will be in the same boat soon. Also stainless steel bolts won't break like steel ones will.

Perry

Quote:

Originally Posted by SStar

I got my Yukon back from the dealer yesterday, everything looks good, I checked the right side and all was intact. and The repair to the left side was more extensive than was first thought. The head was removed and sent to a machine shop to extract the broken bolt. The exhaust manifold, heat shield, manifold gaskets, head and valve cover gaskets were replaced. Several hours labor was incurred. I was lucky, my deductible on the warranty was $100.00, the dealer is working with the warranty company for the balance. I was highly impressed with the way that the dealer handled the situation.
After talking with the dealer and several independent mechanics, I would highly recommend checking your vehicles, especially the V8 GMs for broken manifold bolts on a regular basis. If you catch it early it might be a simple repair to extract and replace the bolt before it develops into an exhaust leak.
If you have a vehicle that is going out of warranty soon it would be advisable to give it a good look over for any problems that need attention.