Exhaust gasket replacement failure.

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nephlyte

FABO Gold Member
FABO Gold Member
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Location
Corpus Christi, TX
Well, i am not a very skilled exhaust mechanic. But i plan to be on the next round of trying.

After reading this: http://www.slantsix.org/articles/manifold-install/types-mounting.htm I realized i made a series of mistakes. So i might as well list them so we can get that out of the way.

I did not finger tighten the exhaust to manifold (heatriser) bolts.
I failed to use anti-seize compound on any part of the whole assembly
I did not modify the head riser gasket even though my car is from 1966.
I did not use a torque wrench.
Other obvious mistakes:

Broke off a stud - this i should be able to fix cause theres still some thread left. But there is another broken stud flush with the head i didn't do, but will not be able to do anything about.

I didn't use all metal lock nuts on the manifold to exhaust pipe bolts. I don't know if its stock, but mine just has bolts going through both and nuts on the other side. I think there is thread in there, but i don't know if thats how it supposed to be. Either way, those bolts backed off on my way from Corpus Christi to San Antonio and i was running an open manifold by the time i got here.

I fixed the exhaust pipe bolts, so the car is running acceptably well. Otherwise, there is no real issue with the car running. Near the broken off bolts, there is no exhaust leaks (i'm sure that will change soon enough). But there are tiny leaks at indeterminable areas. Because the exhaust manifold is largly out of view, i can't see exactly where there is smoking coming out, but its clearly coming out at the heat riser gasket.

To complicate the matter, inspection is up and i need to get a new sticker. They will never pass me with some exhaust coming out of strange places under the hood.

Its a lot of problem, i know. But now i have a few questions before i tear back into this.

Will an auto parts store have those studs? I noticed they were diff threads on each side and i'm sure the length is important. If an auto parts store won't have them, where could i get some? I'd like some new ones so i don't risk breaking more.

What do i do about that broken off stud that flush with the head? Its the one closest to the firewall, which is a big problem. I'd rather not take out the engine or the head to get at it.

Does anyone know a place in San Antonio, TX to get an easy going vehicle inspection?:-D

Just in general, is there any other notes i should make before starting agian. I probably won't start 'till the weekend. We'll see how it goes. Thanks in advance.
 
The busted off stud can be gotten out pretty easy. Start with a small drill bit in the center (use a punch to mark the center) then work your way up so the hole is one size smaller than the stock threads the run a tap to clean out the threads. You may want to go one size bigger than stock just to make sure all the bad threads are out. You can get new studs at any hardware store, I get mine from the local Ace Hardware because they are stronger than the cheap ones that Home Depot or Lowes sell.

When I lived in Richlands/Jacksonville NC we had a back woods garage that would pass our cars if the lights and horn worked and we gave him a case of beer.
 
"Next, you'll want to carefully prepare the surfaces for the new metal inter-manifold gasket. The current stamped steel replacement gaskets are poorly designed and tough to persuade to make a good seal so clean and file flat the contact areas. The old, long-obsolete "problem solver" gasket (a thicker metal-asbestos-metal sandwich material gasket http://www.slantsix.org/articles/manifold-install/inter-close.jpg) was much better at sealing a worn and pitted surface. My experience has taught me that unless you have reground these surfaces or have a brand new intake and a brand new exhaust manifold, this all-metal gasket simply will not seal on a worn surface. This is the place to use High Temp. RTV Silicone. I use copper high-heat RTV from the parts store or Chrysler Mopar High-Temp RTV to help ensure a seal"

If you cant find the "problem solver" gasket try some of that copper gasket spray on both sides of the crappy thin metal one. Let it ste up and spray it on thick and give it a few coats each side. I have done this in the past with pretty good luck.
 
www.pentastarparts.com.au has the gasket you need to seal an old manifold. It is a composite gasket that is graphite coated and will seal most anything. They also have an intake/exhaust to head gasket made from the same material. Search the website for hotbox gasket and/or intake gasket. They can have one to you in around a week even though they are in Australia. There is a box to check on the website to get prices in US dollars.
The broken stud is fairly easy to remove. The stud is 5/16" so I just drill a 1/4" hole and retap for 5/16-20. The end holes will be into the water jacket so remember to coat the threads on the new stud with some sealant or you will have a water leak. Bolts and nuts on the exhaust flange is not that uncommon. My '66 Valiant is like that and the manifold I pulled off a '70 truck is the same way. Put them together with hardened lock washers and you will be fine. Hope this helps.
 
Alright, took everyone's advice. It feels nice and sturdy now.

Once i got it off, i realized that there was no leaking on the exhaust/intake gasket itself. The only leaks were at the heat riser gasket and the exhaust manifold to pipe gasket. Luckily, my bicycle had two flat tires when i needed to get to the store. So, after a 2 hour walk to the store and back on this cloudless 90 degree texas day, i continued.

So, i put some high temp goop on the heat riser and exhaust pipe gasket, replaced that broken stud i was talking about, put the gaskets on and bolted it all up, using the right order.

Now i have to take a break for school stuff and couldn't start it right away. Usually, i just start it up up to enjoy my success, then i had a thought.

That high temp goop says that it will cure in 12-24 hours. If i let it cure, would that make the seals stronger? If so, that could be a 12 hours well spent.

Any thoughts?
 
player, i'm with you on that stupid little flapper.

Next time i have to do this, i'm gonna punch that little ***** out and weld the holes shut. It has no purpose south of the mason/dixon line.
 
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