My 99 Silverado( 5.3) developed an exhaust leak which I attributed to a blown gasket around the manifold/head mating surface so I ordered new ones to put in,a job I intended to do today.Once I started at the job I noticed broken exhaust bolts,2 on the drivers side where I noticed the sound(leak) coming from and one on the passenger side.The real problem I can see from a preliminary inspection is that one of the bolts broke off almost flush with the head from what I can tell with a depth gauge (piece of wire) the other 2 have enough left that a stud extractor should HOPEFULLY get them out.And as fate would have it the one that broke off flush is the very back one on the drivers side #7 cyl with next to no room to work on it(*^&#@ explicative X 4).What am I up against here am I going to have to take the head off to get this f ' in bolt out or has anyone successfully removed one still in the engine?I know this is a loaded question as I don't have pics yet and nobody can see what I'm up against here but hopefully someone has seen a similar situation.

I've had good luck on cast iron heads center punching and using a 5/16 inch carbite steel drill and retapping with a 3/8 inch bottoming tap.
I have had problems on aluminum heads. The drills want to wander I've taken them to a machine shop and they fill the hole up with mig wire.
If you have a good spot and drill straight you could try an easy out but be very careful and don't break it off. You also can try an angle drill with a left hand drill bit.
I tried to talk Lisle into making a hole saw with an ID about .005 larger than an 8mm diameter stud. I checked and the smallest hole say I can find is 1/2inch saw.
Then supply a tap and thread insert. I really think it would be a big seller.
You just might consider a valve job I really think you will have to pull the head.
The only other option I can think of is using a drill bit guided by the manifold which would be still in place then using an heli coil.
None of the options are good so try what you think will work.

yea i agree your options are'nt that good.best to just pull the head on the 1 thats flush but then you'll talk yourself into pulling both!!!Good Luck

You can go through the wheelwell,pull the fender lining out and be careful of the cilps holding it in.do not drill in too far,one is a coolant passage and coolant will come out.

[quote=327chevy]My 99 Silverado( 5.3) developed an exhaust leak

the broken exhaust bolts are an interesting problem with your vehicle...why do you think this occured ?


I have replaced cross over pipes and exhaust manifold bolts with drilling out the old rusted studs 3/8-16....using a 1/4 drill bit drilling out the stud is not difficult if you can get access..90deg. drill??? the manifold is much harder than the stud so it should stay in proper position, using the smaller 1/4in drill bit will keep it from binding and breaking off....use cutting oil and retap holes....use high strengh grade 8 studs not 3...


on the depth of dilling place a collar around drill bit to limit penitration..

good luck

I am thinking the bolts are breaking off from fatigue but am not 100% sure on that;I have been told that there is a difference in expansion rates from the aluminum head and steel bolt so mabey I'm not giving the engine proper warm up time before driving to work.As it is I only have to drive about 2 miles to work so a lot of the time the engine is just nicely getting up to temp when it is shut off for the day.
A 90* drill may do the trick for me I really don't want to have to take the head off right now as I am rather pressed for time and don't want to tie up my truck for a couple of days.If anyone has had a chance to look at the area I'm referring to on their own truck you'll see as there is next to no room to get at the very back bolt on the drivers side and I'm not sure taking the inner fender liner out will even do much for me but I'm willing to try anything.

We have an arc welder with a special rod, sorry cant remember the name. Basically you hold a nut on the out side of the hole, fill it with the welder and the rod, and the flux only lets it weld to the stud. Sorry its vague but its out there and better than pulling the head.

I would appreciate more information. I could see it working on a cast iron head but think it would melt an aluminum head. Is this correct please reply.
Is this a mig welder with a flux core or a DC reverse polarity welder. Or is it a buzz box.

I believe this to be an inherent problem in the earlier model years (1999-2002?) as the manifold bolts are smaller in those years than the later model years. I have a broken one on the drivers side. I know several people on this board have had this same problem. Let me know what fix you go with!

Sincerely,
Matt

The more I've been looking into this problem I see that it is quite common especially the rear ones.It seems the most common fix is to weld a washer to what's left of the bolt and then a bolt to the washer so it can be turned out "hopefully".

The more I've been looking into this problem I see that it is quite common especially the rear ones.It seems the most common fix is to weld a washer to what's left of the bolt and then a bolt to the washer so it can be turned out "hopefully".



this welding to the remaining stud another stud/nut to what is left then while the weld is still hot attempt to remove....

[quote=327chevy]My 99 Silverado( 5.3) developed an exhaust leak

the broken exhaust bolts are an interesting problem with your vehicle...why do you think this occured ?


the broken manifold bolts are extremely common on 99-2000 5.3 motors. 2001 they changed to a larger bolt and haven't had the issue anymore. same issue has plagued the earlier 6.0l. if the bolt did break flush with the head we have always had to pull the head at out shop. no way around it. sometimes you can get lucky with the ones still sticking out but the chance of it breaking is pretty good. may i recomend alot of PB rust penatrator.

Probably the most amazing rod they have is the MG-600 rod which is
designed for stud removal. It is a special high strength alloy
rod coated with a special flux. If a stud is broken off down in
a hole, one simply pushes the rod down on the stud. The flux
flows out and protects the threads from the metal. The metal builds up
until it protrudes from the hole. It is allowed to build up a bit
more, then a nut is laid down over the protruding alloy and welded to
it. Then the nut is turned, removing the stud. Supposedly the alloy
is strong enough not to break before the stud comes loose. They claim
it can also be used to remove broken taps and drills. They say this
rod can also be used to weld things like automotive springs!

http://yarchive.net/car/welding.html

found them, I have used these rods and they work but you need an arc welder.