Small Block Chevy Exhaust Manifold Bolt Sheared

[QueBota]

Question on one of my own this time.

94 K1500 Suburban (230K), exhaust leak rear passenger side. Manifold bolt sheared off, still protuding partway up
the exhaust manifold bore. I thought I might have gotten lucky and the bolt had just backed out. I noticed
the retainer between the adjacent bolts had rusted away. Tried to thread in a new one, no luck. Got out
the inspection mirror, looks like it sheared off about 1/2 inch or so above the head.

Would like to fix this without removing the exhaust manifold if possible, the remaining five bolts are crusty,
I would be suprised if they all came out without shearing.

Anyone ever blew out the remaining bolt with the manifold still on?

Would be relatively easy to fix with the manifold off, although the passenger rear offers the least amount of
access. I think there is enough bolt left to grab it with Vise Grips.

I was thinking of trying to make a centering jig based on the diameter of the bore of the manifold mouniting hole.
That way I'd have a shot at drilling (left hand bit) into the center of the bolt and hopefully backing it out.

What do you guys think?

Thanks,
Dave

 

[deerefan]

Had a similar issue and ended up removing the manifold. If you replace the bolts, you can use heat to loosen. I soak them in penetrating oil and let sit overnight. Of course I dont use heat when I do this!! Also, try this when engine is warm, maybe 15 min after running. Bolts may loosen some.

 

[QueBota]

Really hoping to do it without pulling the manifold if possible.

Need to find a good welder/fabricator and see if they can perform the trick. I have seen it done many times on the bench and also in the vechile with the heads still on. OxyAcetylene torch, heat the offending item until it is just about molten, kill the flame and blow out the metal. Usually need to run a tap afterwards to clean out whats left.

Not sure if that can be done working through the mounting bolt ear. It would have to be the passenger rear, not a lot of room to work.

I just finished up replacing the water pump, ps pump and lines less than a month ago. Thought I was good to go through the winter.

Thanks,
Dave

 

[dodge man]

I did one on a 383 in a Dodge Challenger years ago. I ended up pulling the head, drilled it out and installed a Helicoil. It took a lot of work but it was for a show car so I painted everything and detailed it while I was at it, so I had other reasons to tear it down that far. I'd say it will be tough to get it out, those things always seem to rust in place really bad.

 

[LindenBruce]

Is this one of the bolts holding the manifold to the cylinder head? If so, you are prolly going to have to remove the manifold to gain access to the broken bolt. There prolly is not enough room to work on it otherwise. Can you post a pic? B.

 

[tcartwri]

The manifold will crumble from the heat of the torch, before you even get the stud hot enough to put the Oxygen to it. There is an electrical way to do it, but you will have to bring it into a shop that has the equipment. Google EDM stud removal.

 

[tcartwri]

BTW; the gasket will have blown out, so you will be removing the manifold anyways. Just putting a new stud in, will not solve your leak. Warm the engine up before you try to take the others out.

 

[QueBota]

Thanks guys, didn't think about the gasket blowing out.

Looks like the manifold is coming off.

May drive it as is for a while, it ticks a bit at cold start and is pretty quiet once the head/manifold warm up.

I have a 3" exhaust with very low restriction, that may be helping a bit.

Dave

 

[tcartwri]

There's one other thing. This is a flat tappet motor, and 230K miles is allot for original lifters. Are you sure you're not hearing lifter tic....

 

[QueBota]

Definite exhaust tick, you can hear it with stethoscope and feel it if you put you hand down there.

Looks like it's going to be a PITA to fix, looked it over again last night. Not a lot of room between the firewall
and inner fender well, acess from the below not very good either. No way I can afford to pay someone to fix
this, around here it would be about $500.

Also going to have to remove the three bolts holding the Y pipe to the exhaust manifold. Those look worse than
the exhaust manifold bolts, very thin and not much left of the bolt head. On the plus side at least I have a chance
of heating and lubing them from the engine compartment side.

I think I'm going to try the jig method first just for the h#ll of it. Need to find a 1/4" deep socket that most closely fits the
bore of the manifold mounting hole. Then I'm going to fill the deep socket with JB Weld or something similar. After it harderns
I will try to drill down the center of the socket using a drill press. Then I hope to place the socket in the exhaust manifold bore
a try to remove the broken bolt with a left hand drill bit. Nothing to lose trying that, if it doesn't work Y pipe will have to be separated
from the manifold and manifold will have to come off the head.

Thinking ARP or something similar for the replacement bolts. Truck has 230K on it, I'm the third owner. 1st owners were an older
couple who used it sparingly and maintained it well (have all paperwork). Second owner was an elevator repair tech, he maintained it
very well (have all paperwork).

Very solid truck, engine, trans and transfer case are all good. Front end needs rebuilt. I have replaced most
of the bolt on parts and the radiator. Weeping oil cooler lines are on the short list. Plan on keeping this as long as possible.

My son will be driving it as soon as he gets his liscense, engine is a little tired, thats a good thing. He won't be breaking any
speed records. Should be safe in the event of any accident.

Thanks,
Dave