For LT1 owners with cracked exhaust manifolds...

[Gorgon]

I recently changed the right exhaust manifold on my 95 vert due to a crack in it. I've heard of quite a few LT1's that have this cracked manifold problem and it seems to typically be on the right side. Anyone with a similar situation that is looking to replace the manifold with the stock replacement needs to be aware of some items.

I ordered the replacement manifold from GMPartsDirect.com which is GM# 12554232. This part is an updated manifold from the original 12554231 that came on the car. Below you will see the two manifolds side by side. You will notice that there is a flange on the old manifold that is not on the new one. This flange was part of the seal between the manifold and the exhaust pipe. The new manifold requires a doughnut gasket to be purchased that plugs into the bottom of the manifold before installing. I never noticed the difference between the two and installed it without the gasket. Needless to say it was a little louder than i expected.

The gasket I purchased from my dealer was GM# 15713154. I sent GMPartsDirect an email about the gasket and how it wasn't available through their site and they informed me that that part was replaced with updated part GM# 15170285. Anyone looking to do this job themselves please be aware of the extra gasket purchase. All in all the job was cheap to do (~$95 for the manifold and $18 for the gasket) and relatively easy to do. The left side will be much harder as the ASR and A/C compressor need to be removed.

And since the car has 96k miles on it I chose to do both manifolds and also change the plugs. It's about that time with the mileage and you need to remove the plugs to do the manifolds anyway. Pics below show new and old manifold and crack in old manifold. I removed the heat shield from the old manifold to get a look at the crack.

EDIT: I guess it might be obvious, but please don't forget the gasket between the manifold and the head, GM# 12552470. These are ~$10 from GMPD.

Leon

[Rain]

Thanks for the post, the corrected info, and the pics - Know many of us will be in that boat one day -

Rain

[Gorgon]

Looking at the receipt from my dealer purchase, they did indeed sell me gasket GM# 15170285, the updated gasket. Also, while changing these out the local Corvette specialist recommended changing the bolts/nuts connecting the manifold to the cats, 3 each per side.

Bolt - GM# 10220453
Nut - GM# 10255857

Ordering the nuts/bolts is a pain. The dealer dinged me $2 for each nut and each bolt totalling about $24. Ordering through GMPartsDirect isn't any better. They sell the nuts in a 5 pack only (you need 6) and the bolts in a 10 pack. You figure it out.

[B17Crew]

This is a great heads up!

B17Crew