[ron cozzo]

I have an exhaust leak on my 67 YS 400 GTO with standard cast iron manifolds. I can see the tell-tale black streak on the block behind the number 4,6 exhaust ports. I managed to put on a new steel gasket without totally pulling the manifold, and I cleaned the head and manifold surfaces well. It still leaks. Is there a trick to removing the exhaust manifold with the engine in? I'd like to check the manifold for flatness. I can't even get the center two bolts all the way out before they hit the engine crossmember. Even with all the bolts detached from the head, I can't move the manifold more than an inch or two in any direction. Also, the car has A/C, one more obstacle. Any advice on curing the leak or removing the manifold would be appreciated. Finally, I'm not completely sure it's the exhaust gasket. The area with the black streak is also near the head gasket. I did a compression check and got 192 and 186psi for the no.4 and 6 cyl's. Could I have a significant leak with those readings? Sorry so long.

[ron cozzo]

I have an exhaust leak on my 67 YS 400 GTO with standard cast iron manifolds. I can see the tell-tale black streak on the block behind the number 4,6 exhaust ports. I managed to put on a new steel gasket without totally pulling the manifold, and I cleaned the head and manifold surfaces well. It still leaks. Is there a trick to removing the exhaust manifold with the engine in? I'd like to check the manifold for flatness. I can't even get the center two bolts all the way out before they hit the engine crossmember. Even with all the bolts detached from the head, I can't move the manifold more than an inch or two in any direction. Also, the car has A/C, one more obstacle. Any advice on curing the leak or removing the manifold would be appreciated. Finally, I'm not completely sure it's the exhaust gasket. The area with the black streak is also near the head gasket. I did a compression check and got 192 and 186psi for the no.4 and 6 cyl's. Could I have a significant leak with those readings? Sorry so long.

[RPM]

192 and 186 psi compression readings are close and don't indicate any cylinder leak. Your exhaust manifold most likely is warped and this can be fixed once you get it out. You may have to lift one side of the engine to get it out The way I have done this is to use a sizzors jask under the oil pan and put a block of wood between the jack and the pan. Remove the passenger side motor mount bolt and loosen the drivers side bolt. Lift the engine up (tilt it) about 1" to 1-1/2". You can keep the bolts in the manifold as you bring it towards the rear of the car and out. You may have to first remove the oil filter and maybe remove the filter adapter.

[Half-Inch Stud]

Yea.

Or, try a steel-reinforced header gasket.

Do not use the white asbestos gaskets - they just blow out.

H.I.

[ron cozzo]

Thanks for the replies RPM and Half Inch Stud. Sorry to waste your time but I solved this awhile ago. I thought for sure that I had posted the resolution to this problem. I hate when people don't post the result of their problems, now I'm one of "them". Anyway, here is what I found. I was positive it was either the exhaust manifold to block, or the head to block that was leaking, because of the location and shape of the black streak that I was seeing on the side of the block. I got under there with the engine running (an uneasy feeling) and ran a piece of vacuum hose around these areas with one end in my ear. It turned out to be nothing more than the exhaust pipe flange was leaking at the manifold attachment. The pipe was at a bit of an angle going to the manifold. Loosened it up and put a floor jack under the pipe to seat it against the manifold, retightened and all is well.