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Discussion Starter · #1 ·
I am pretty sure I have a leak in my exhaust manifold, by the sound I am hearing. Seems to be loudest when the engine is first started cold. My question is can I wait to replace the manifold gasket? I had a motorcycle that had a hole on the pipe close to the head. Someone told me that when I turn it off, cold air rushes in and can warp the valves. Is this true? And can it happen to the Z?

I want to wait until summer to do it when I plan on replacing the head with a good used one. Do it all at once. Because my cam is worn very bad I found that the easiest way would be to replace the head with a good used turbo head. Most of the Z's I see at the junk yard don't have the kind of wear mine does to the cam. Also much cheaper, about $100 at the place I go to, just waiting to find a turbo head there. Sorry for the long post...
 

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Discussion Starter · #2 ·
> I am pretty sure I have a leak in my exhaust
> manifold, by the sound I am hearing. Seems
> to be loudest when the engine is first
> started cold. My question is can I wait to
> replace the manifold gasket? I had a
> motorcycle that had a hole on the pipe close
> to the head. Someone told me that when I
> turn it off, cold air rushes in and can warp
> the valves. Is this true? And can it happen
> to the Z?

> I want to wait until summer to do it when I
> plan on replacing the head with a good used
> one. Do it all at once. Because my cam is
> worn very bad I found that the easiest way
> would be to replace the head with a good
> used turbo head. Most of the Z's I see at
> the junk yard don't have the kind of wear
> mine does to the cam. Also much cheaper,
> about $100 at the place I go to, just
> waiting to find a turbo head there. Sorry
> for the long post...
i just had the same problem...i decieded that i would tackel the prob my self and i saved my self a lot of money....
ok with the L28ET it is inportant that you get it fixed asap,( my oppinion ) because you will run into problems that will endup causing more problems that will endup in deductions from your wallet... how long has it been leaking??? how loud is it?... check your block for exauhst soot...
if you decide to replace the the gasket your self let me know and i will talk you through it, because the exhaust and intake gasket are 1 piece... you will need to remove the intake manifold and exhaust manifold...
contact me via ICQ 11603581
jeffB Tallahassee FL
 

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> I am pretty sure I have a leak in my exhaust
> manifold, by the sound I am hearing. Seems
> to be loudest when the engine is first
> started cold. My question is can I wait to
> replace the manifold gasket? I had a
> motorcycle that had a hole on the pipe close
> to the head. Someone told me that when I
> turn it off, cold air rushes in and can warp
> the valves. Is this true? And can it happen
> to the Z?

> I want to wait until summer to do it when I
> plan on replacing the head with a good used
> one. Do it all at once. Because my cam is
> worn very bad I found that the easiest way
> would be to replace the head with a good
> used turbo head. Most of the Z's I see at
> the junk yard don't have the kind of wear
> mine does to the cam. Also much cheaper,
> about $100 at the place I go to, just
> waiting to find a turbo head there. Sorry
> for the long post...

Leslie, I had a similar problem on my 81. After talking to a few z people I was told it is common for the exhaust manifold to warp on z's. They said it was no problem to take it off and shave it down. My local dealer said they've done several over the years and would run about $150, unless a stud was broken. Well, getting in there a stud was broken and it cost more.

Anyway, point is don't just change the gasket, check to see it is not warped. I'm not sure if that was a problem on the '83's but my guess is they're all prety similar. I would not wait until a stud breaks off in there. It did fix my problem.

Good Luck,
Randy
 

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> Leslie, I had a similar problem on my 81.
> After talking to a few z people I was told
> it is common for the exhaust manifold to
> warp on z's. They said it was no problem to
> take it off and shave it down. My local
> dealer said they've done several over the
> years and would run about $150, unless a
> stud was broken. Well, getting in there a
> stud was broken and it cost more.

> Anyway, point is don't just change the
> gasket, check to see it is not warped. I'm
> not sure if that was a problem on the '83's
> but my guess is they're all prety similar. I
> would not wait until a stud breaks off in
> there. It did fix my problem.

> Good Luck,
> Randy
I have an exhaust leak too, I've been driving my 80 280ZX with the windows down. Did I read right, I must take the intake AND the exhaust manifolds off to change the exhaust manifold gasket? Can any of you shead some light on this for me?
Thanks Steve
 

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Discussion Starter · #5 ·
you're not going to warp a valve unless the leak is extremely bad. i would pinpoint where the leak is coming from because z's will leak in some other spots. the exhaust flange gasket will leak at the downpipe and also the pipe itself will crack in half where the two pipes become one. you can't see it because the shielding is in the way. z's do have manifold problems though, they can warp and break the bolts off on the ends. happens to almost every car. but it can take years before a leak actually develops. of all the z's i've seen, i can't remember one leaking at the manifold itself, it was always that downpipe cracking.
 

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> you're not going to warp a valve unless the
> leak is extremely bad. i would pinpoint
> where the leak is coming from because z's
> will leak in some other spots. the exhaust
> flange gasket will leak at the downpipe and
> also the pipe itself will crack in half
> where the two pipes become one. you can't
> see it because the shielding is in the way.
> z's do have manifold problems though, they
> can warp and break the bolts off on the
> ends. happens to almost every car. but it
> can take years before a leak actually
> develops. of all the z's i've seen, i can't
> remember one leaking at the manifold itself,
> it was always that downpipe cracking.

Yep, my 72 warped the ends on the exhaust manifold and broke off the studs. It's just a result of the dissimilar metals used in the head and exhaust manifold (along with the fact that the manifold's rather long which makes it more vulnerable to warpage) I found if you replace the studs with Socket head grade 12.9 bolts which are tons stronger in clamping power, It effectively prevents them from popping off again. (so far so good anyways). This coupled with having it ground flat again at a machine shop will cure the problem if that's what it is. But like it was stated, it could be the pipe itself too or any of the other gasketed sections in the exhaust system.
 

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Discussion Starter · #7 ·
> I am pretty sure I have a leak in my exhaust
> manifold, by the sound I am hearing. Seems
> to be loudest when the engine is first
> started cold. My question is can I wait to
> replace the manifold gasket? I had a
> motorcycle that had a hole on the pipe close
> to the head. Someone told me that when I
> turn it off, cold air rushes in and can warp
> the valves. Is this true? And can it happen
> to the Z?

> I want to wait until summer to do it when I
> plan on replacing the head with a good used
> one. Do it all at once. Because my cam is
> worn very bad I found that the easiest way
> would be to replace the head with a good
> used turbo head. Most of the Z's I see at
> the junk yard don't have the kind of wear
> mine does to the cam. Also much cheaper,
> about $100 at the place I go to, just
> waiting to find a turbo head there. Sorry
> for the long post...
Leslie, if you are going to change the head anyway, that would be the time to replace the intake/ exhaust gasket, and r and r any broken studs. If the studs on the end of the head are broken, you can bet your manifold is warped.
By the way, we have P90 heads in stock, right now.
call if interested. thanks, Joe 1-800-533-5659
 

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If the leak is on the gasket...

would that make a gasket stuff work that they sell at auto stores. I can see my leaks because mine shoots out black smoke all the time. And One other thing, how come air comes out so hard from my exhaust? Is it normal for Z's? It comes out stronger than my uncle's '75 Celica, 74' 911, '84 928S and Ferrari Mondial.
 
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