Hello all,

My 85 IROC with a TPI 305 has a pretty nasty exhaust leak on the right side of the engine. I really havent given it a good look, but when I rev it up a bit I get a puff of smoke between the engine and firewall. I am thinking it may be an exhaust manifold gasket. Its not really getting any worse, but the raw exhaust is getting into the car through the vents and its starting to get to me!

The first question is, how difficult is it to remove the manifold? I have a compressor and full array of tools at my disposal. The only real problem I see is that with my luck every manifold stud will break in the head. I really dont want to deal with that in the garage on by back!

What do would you expect a good exhaust shop to charge to remove the manifold?

Second, are they any other parts in that area that could cause a leak?

Thanks!

 

Went through all the same questions with ours. Try first seeing if you have a loose exhaust manifold bolt. The stock manifolds dont have gaskets - I tried putting a gasket on our stock manifolds, having them resurfaced and none of it worked.
We ended up putting on a set of Headers.
There is a lot more to do if you put on headers. Let me know if you go that route and I'll save you some headaches down the road.

 

There has to be a gasket between the manifold and the head, doesnt there?

 

Yeah they do... Maybe some one before you installed them w/o or you got the wrong gaskets, but yeah they are supposed to have them...

The manifolds are a hassle to remove, but with some patience and a good assortment of tools to mix and match it should be doable. I think bolts seizing are more of a problem in aluminum heads, but you should definitely be careful none the less. On the few SBC's I've taken manifolds off of, the bolts to the head were always loose, like finger tight... Hence the source of the leak. The problem's were in the studs that mount the y-pipe to the manifold. They seem to seize up. I ended up having one of the studs strip out the hole in the manifold, but I was able to run a 1/4" bolt/nut w/washers... Could have drilled and tapped for a bigger stud, but why bother? The other hassle was mating the y-pipe back to the manifolds, but if you only take one manifold out it should'nt be a problem.

Anyway, if you do end up getting the manifold out, you can take it and give the mating surfaces a good wirebrushing/sanding, or whatever, just to clean 'em up a bit before reinstalling w/ new gaskets.

Also, the rear bolts to the heads may be a hassle, esp. on the passenger side with the A/C box...

 

I will check all the nuts and make sure everything is tight, but all I see is pain and misery if I try to tackle this one........

 

There has to be a gasket between the manifold and the head, doesnt there?



95% of the time they never put gaskets of the exhaust manifolds cuz they actually do a worse job of sealing than just bolting it straight to the head IMO.(headers need them though)

three things that could have happened are 1. cracked manifold 2. warped manifold 3. donut gasket where the y-pipe connects blew out.

The manifolds aren't the worst to take out, just make sure you prelube the bolts with a ton of WD-40.

 

How does the y-pipe connect to the manifold? I had heard there is no gasket there either, rather some type of sleeve......

 

OK, confirmed the leak is from the exhaust manifold gasket back near cyl #8.
The heat has turned the spark plug black! Plus I found my knock sensor is trashed and I didnt even see the wire for it.
I am just going to take it in and get it replaced. Then get a new knock sensor and find the wire!