: Exhaust leak/tick

09-25-11, 03:28 PM
I've been hearing this for a while from cold start until a few minutes into the drive. Always assumed it was manifold to cat or cat to exhaust flange. Nope. Finally had the brilliance to check this, and this is what I found.


The thing that bothers me most is this exact bolt on this side exhaust manifold (driver's side) had done this exact thing on my 95 Fleetwood that I traded in for this car. Those are known for doing this. I had assumed something that underwent a clean sheet design (notice the split flange of the manifold) wouldn't have stupid manifold bolt issues, unless this is just my lucky day.

Any advice for the best way to remove the remainder of this bolt and replace it? Headers are not happening, so don't go there, please...

I assume the manifold has to be dropped to access the protruding piece of bolt. I was thinking maybe disconnect the cat from the exhaust, which would hopefully free up the manifold to drop a few inches down, giving me access. Then I'd use one of those female screw extractors. Ideas?

09-26-11, 02:21 AM
You dont wanna change due to emmisions?

In anycase you will need to remove the cat bolts than remove the other bolts holding up the headers.

I would give them all a good spray of WD-40 and then try and get them off. I would also get a new pair of gaskets and keep the other spare for the other side if its needed.

Try and get the ARP header bolts, they are stainless and use a dab of anti-seize so they dont get stuck in the heads as well. Also a dab of red loctite for the nut side and torque them to 18lbft starting from the center...

Have fun and make sure you plan on a 2-4 hr job when doing this...

09-26-11, 08:43 AM
Should I hunt down a manifold to cat gasket? I recall them not being available seperately but magically some C5 P/N does work. Anything for the cat to exhaust? The car came with a Magnaflow so I don't know what's in there. Is it not possible to leave the cat on the manifold and disconnect at the mid-pipe? Or will I not have enough room to maneuver the manifold away from the head if I do that? I probably won't be doing this for a while so I might as well collect data.

Any sources for the ARP bolts? Or are they studs?

09-26-11, 09:09 AM
The manifold to cat gasket is a ring, not a regular gasket. The cat to exhaust is a donut gasket and I'm sure they left that on there to mate the magnaflow you have. I believe you are thinking of that donut that can't be replaced but a corvette part number is the exact match.

I'm almost positive I've seen people that have removed the cat and manifold together as one so there should be enough room. If you are going to separate the two, make sure you let some penetrating oil soak on those cat/manifold studs/nuts for at least a night. Mine were a major PITA and ended up having to grind the nuts off.

09-26-11, 09:18 AM
That's kinda why I was hoping to drop the manifold with the cat on it...but I guess I should plan for the worst. I'm sure mine will be worse than yours were (109k, 2 years older). I'll probably do this on a lift which may help somewhat.

What size exhaust bolts do these use? Is it still 3/8-16 or something metric by now? Why stainless instead of Grade 8/10.9?