[Skidmark]

I looked for this answer in the archives, but didn't see anything even though I'm sure it's been covered many times.

Anyway been chasing lifter tap / exhaust leak wasn't sure which one it was so I put a shop vac exhaust in one tailpipe and blocked the other one. Sprayed soapy water on manifolds and down pipe connectors. Wow, I was surprised to find both manifolds leaking on all four corners and both down pipe connectors. Amazingly the tap wasn't that loud. I'll be getting the graphite gaskets to replace the metal ones in there now.

I've got a 72 Lemans w/400 auto in it no ac at the moment.

Has anyone removed the manifolds with the engine in the car? I can see the intermediate steering shaft might be an issue.

[tom s]

Actually you don’t have to remove all bolts,I leave the 2 ends in and remove the rest.I VERY carefully notch the end holes so the gaskets can be slid down and rest on the end bolts.Start the others in and TQ them down.I have not don’t that on RAs but have done Long Branch and D port headers.The Remflex gaskets crack and break EZ so you have to be VERY careful.Tom

[scott70]

I recently replaced my exhaust manifolds with RARE oversized Dport manifolds and installed 3" headpipes. I removed the oil filter adapter , the starter and Zbar Pulled out manifolds and installed new ones and didnt even have to jack the motor up or anything. This was on my 70 gto.

[Sirrotica]

I've replaced dozens in the chassis. You'll want to remove the motor mount bolts, and raise the side you're working on. As the engine is raised on one side it also rolls exposing the bottom of the head making it much easier to get at the bolts, and also chase the threads with a tap, preferably a bottom tap. Jacking up one side at a time maximizes your working room, If I'm working on the ground, I use a bottle jack, and appropriate wooden blocks. On a lift I'd use a floor jack, and a length of 2x4. I also use short pieces of 2x4 blocks to put in between the motor mount and frame in the event something shifts, and the engine were to drop, you don't want your hands pinned in between.

The steel shim gaskets last a heckuva lot longer than header gaskets do, so I'm not sure why you want to substitute header gaskets. If you want to seal them up tight, coat both sides of the steel shim gasket with high temp RTV, let it sit about 15 minutes to skin over, and install the gaskets. The RTV seals any minute irregularities in the head, or the manifold. I'd also coat the bolts with Never Sieze before installing them into the head. I've worked on Pontiacs since 1970 when I graduated from high school, and auto mechanics at the local vo tech, I have years of job related Pontiac experience. That would be how I'd repair the problem you describe on my own, or a customer car, but it's your car, and your choice. It's not a simple job, nor easy, but I believe I've given you the best way I know how to do it, from past experience.

Hope that helps you carry out your repair efficiently.

[Skidmark]

"The steel shim gaskets last a heckuva lot longer than header gaskets do, so I'm not sure why you want to substitute header gaskets"

Oh, I didn't realize the graphite gaskets were for headers only. I won't use them in that case. I'll try what you do and see how it goes.

Thanks for the help.

[Skidmark]

Originally Posted by scott70

I recently replaced my exhaust manifolds with RARE oversized Dport manifolds and installed 3" headpipes. I removed the oil filter adapter , the starter and Zbar Pulled out manifolds and installed new ones and didnt even have to jack the motor up or anything. This was on my 70 gto.

Thanks, glad to know I don't have to pull the engine.

[Skidmark]

Originally Posted by tom s

Actually you don’t have to remove all bolts,I leave the 2 ends in and remove the rest.I VERY carefully notch the end holes so the gaskets can be slid down and rest on the end bolts.Start the others in and TQ them down.I have not don’t that on RAs but have done Long Branch and D port headers.The Remflex gaskets crack and break EZ so you have to be VERY careful.Tom

Thanks Tom.

[Baron Von Zeppelin]

If its a 72 engine with 72 model heads , it probably doesn't have any bolts on the outer ends of the manifolds .
Those are crazy

[Skidmark]

Originally Posted by Baron Von Zeppelin

If its a 72 engine with 72 model heads , it probably doesn't have any bolts on the outer ends of the manifolds .
Those are crazy

It is 72 w/ 7k3 heads. So missing the outer ones.

[Bruce Meyer]

If you were leaking at the exhaust flange there is a good chance the metal shim gaskets were rattling around messing up the gasket surface. Ive seen several Pontiac heads where the exhaust flange needed to be milled a bit to make them flat again. Check to see how the flanges on the head and manifold look before you reassemble. If they are messed up you might have to run header gaskets instead of the metal shim gaskets. Personally I never run the metal shim gaskets due to this problem. I run Fel-Pro header gaskets and never had a problem since.

[Skidmark]

Originally Posted by Bruce Meyer

If you were leaking at the exhaust flange there is a good chance the metal shim gaskets were rattling around messing up the gasket surface. Ive seen several Pontiac heads where the exhaust flange needed to be milled a bit to make them flat again. Check to see how the flanges on the head and manifold look before you reassemble. If they are messed up you might have to run header gaskets instead of the metal shim gaskets. Personally I never run the metal shim gaskets due to this problem. I run Fel-Pro header gaskets and never had a problem since.

Thanks Bruce, I'll definitely check everything out after disassembly. I know like anything else there's a million ways to skin a cat, some guys swear by the thin metal gaskets. I checked out the remflex to see about using on factory manifolds. I might use them if not I'm going the same route as you.