# Leaking exhaust manifolds on 67 GTO 400



## xkeots (May 16, 2009)

After doing a body off my 67 GTO convertible I am now doing the redo. Test driving, retighten one, etc. I put a new exhaust in and had my auto His/Hers 400 tranny rebuilt, I found that my exhaust manifolds to the motor are leaking. I was able to remove the right side and have my machine shop plane down the exhaust as it was warped. One center bolt snapped. I was hoping for a temp fix that all of the other bolts and new gasket would close the leaks, wrong. I also have a bad leak on my left side with frozen bolts. 
Am I better off removing the motor ir leaving it in and pulling both heads, bring them to my machine shop, let them remove and re tap the holes and clean the valves and heads? Then replace them. Anyone out there with experience on this? 
When the exhaust wasn't in, it was so loud I couldn't hear the manifolds, niw I do.
ThNks
Jax
67 GTO


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## Goat Roper (Oct 28, 2014)

Soak the broken bolt with Kroil if there is any of it sticking up strike it flat with a file, center punch it then drill for an easy out.
Soak for a couple of days adding a little each day.
You may need to use an angle drill to drill it.
I wouldn't remove the heads unless you think they need to be rebuilt.
I never reuse manifold bolts, they get stretched and the metal gets fatigued from heating and cooling.
Order a new set from Ames and always use anti seize on manifold bolts before reassembly.
Also order the locking tabs, factory is 4 of them one on each end some guys use one on each bolt.
To remove them always tighten them a bit until they move before backing them out.


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## BearGFR (Aug 25, 2008)

Next time I have to fight with my headers, I'm going to replace at least two of the bolts on each side with studs, probably one on each end of the head. Trying to hold the header up and get a bolt started when you can't see anything is just not as much fun as it used to be.... 

Bear


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## geeteeohguy (Feb 2, 2008)

Studs are a great idea....especially if you use brass nuts. Me, BTDT on these, and I would pull the heads and have them repaired unless you are super good with an angle drill and broken bolt removal. I have done this 'in car' and it is VERY hard to see if you are centered on the broken stud, and it is very hard to evenly center punch and drill a jagged and broken stud with the steering shaft, A-arm shaft, etc. in the way. And if you miss your mark, you are pretty much going to pull the head anyway. This kind of work is never any fun, especially the second time. Keep us posted. What Goat Roper said applies IF you have some bolt left proud of the head, that you can work with. If so, I would definitely go that route, and use some heat from a propane torch, too. Tiny little vice grips are your friend here.


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## PontiacJim (Dec 29, 2012)

Here is a company that makes a tool for precise drilling & removal of broken exhaust bolts. The down side is I don't see anything specific to Pontiac heads. However, what may be able to be fitted to the Pontiac head is what they call the* Bushing Clamp*. It has a hardened bushing that guides the drill straight. It has a slot in the middle of the tool and it might be possible to run an adjacent bolt from the exhaust side that is good so you can tighten the Bushing Clamp in place over the bad bolt to be removed. You might get away with only having to lift your engine to get at the broken bolt.

In any case, you may want to check out their system just to see how it works as it may give you some ideas. They state they can custom build a tool for your application, but it may cost, so you would have to weight out the cost of the tool versus the head removal & installation plus the machine shop work - it may balance out. Then once you use the tool, sell it on the forums as "used" and recover some of your money back. Check it out here: Bushing Clamps


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## Goat Roper (Oct 28, 2014)

PontiacJim said:


> Here is a company that makes a tool for precise drilling & removal of broken exhaust bolts. The down side is I don't see anything specific to Pontiac heads. However, what may be able to be fitted to the Pontiac head is what they call the* Bushing Clamp*. It has a hardened bushing that guides the drill straight. It has a slot in the middle of the tool and it might be possible to run an adjacent bolt from the exhaust side that is good so you can tighten the Bushing Clamp in place over the bad bolt to be removed. You might get away with only having to lift your engine to get at the broken bolt.
> 
> In any case, you may want to check out their system just to see how it works as it may give you some ideas. They state they can custom build a tool for your application, but it may cost, so you would have to weight out the cost of the tool versus the head removal & installation plus the machine shop work - it may balance out. Then once you use the tool, sell it on the forums as "used" and recover some of your money back. Check it out here: Bushing Clamps


That is a cool looking tool.
If I can get a good center and hole started I have used an oak block drilled in my drill press putting it on the bit and sliding it down to the surface to keep the bit centered on the bolt.
Also reverse bits should be used, I have had broken bolts back themselves out after drilling the pilot and going to a larger bit.


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