How would (or could) a poor seal between the exhaust manifold and the exhaust pipe impact performance, noise, milage?

How would it affect O2 sensor readings?

If a leak/poor seal did affect O2 sensor readings, would this impact fuel efficiency?

I disconnected the exhaust pipe from the exhaust manifold in order to replace my starter the other day. I found that one of the nuts, on one of the three exhaust manifold studs, wouldn't budge. The stud failed, twisted and broke with the nut siezed on it. There was enough of the stud extending past the pipe /gasket/ manifold to show that the bolt had not been fully tightened to begin with and that the pipe/gasket/manifold had probably not been sealed and probably leaked etc.

Cheers,

Thomas

 

It would affect all of the above. You need to get it out of there and replace it. It should also be throwing a service engine light code.

 

I just found 2 out of 3 nuts missing on my passenger side manifold to y pipe connection. I never threw any codes and the engine ran perfectly. I just had to replace the nuts and I was all set. In your case, you may be able to cheat and use one of those external repair clamps if you can't get the stud out. On our vehicles, this joint doesn't flex so the repair clamp should last.

 

DITTO, that leak will cause a loss in power, MPG and be hard on the cats so don't wait around, get it fixed.

 

Depending on which stud broke you can effect a temporary repair with a manifold c-clamp you can get at auto parts stores.

 

x2 ive had one on my jeepster for years

 

Thanks for the sanity check etc....

no SEL as of yet....

Ordered new gaskets, bolts, and studs last night.

I suspect I will end up having to remove the exhaust manifold and drill out the broken stud.

At first glance it looks pretty straight forward (famous last words). Is there anything that needs to be removed to get to the exhaust manifold bolts and remove the "starter side", even numbered cylinder side, exhaust manifold? (is that the "right side"?)

Can I reuse the bolts?

Should I use an anti-siezing compound on the new studs and nuts? Any recommendations?

Thanks very much...

Cheers,

Thomas

 

oh.... The stud that twisted off is the one closest to the engine block.

I hope I'm wrong, but I don't think the external clamp is going to work...

even if there is enough room to accomodate the clamp, I'll still have to grind off/ remove the remaining stud that extends past the downpipe flange. To do that, I'm pretty sure I'll have to remove the exhaust manifold.

I'm going to take another look to confirm... cross fingers...

Cheers,

Thomas

 

I have drilled out broken studs in place but it was a definite "pain in the arm" Best bet is to replace all the studs, nothing worst than putting it back together and having one go "tink" and fall out when you tighten it.

 

Well, the idea of the clamp is so you don't have to remove the manifold to use it. It doesn't have to go exactly where the stud is, assuming there's room.
Drilling out manifold studs can be a real pain to get it right. If you can't have the vehicle out of service for long I'd consider just getting a used manifold if you're removing it anyway, then work on the other one at your leisure and sell it or keep as a spare.