Exhaust Question

[tomking]

My 73 Manta has the stock manifolds on it and it sounds like it's leaking. I replaced the I/E manifold gasket but that didn't change anything. It sounds like it is exhausting into a can, putt, putt, putt. Having never heard a leak at the gasket where the heat riser connects to the bottom of the intake manifold, and not being able to detect the leak anywhere else, I am guessing the gasket between the two manifolds is shot and leaking. Any ideas from those more experienced? I dont want to charge into that job unless I am pretty sure that is it, for obvious reasons. If I do however I will install one of the home made sprint manifolds and abandon the heat riser connection. Thoughts??

[yellaopelgt]

Not that I really have any clue as to what I talking about but....whats the thought of spraying some really soapy water on it when its cold, starting it up,and looking for bubbles????SORRY.... if its the INTake the ol w-d-40 thing would work in opposite( car would rev up)

HTH Joe

[opelbits]

Tom-

I, too, have never had a problem with the intake to exhaust manifold gasket.

On my Manta, though, I developed a leak on the head pipe. It was on one of the two down pipes, but on the side facing the other pipe. You could hear it, feel it, but not see it.

Any chance the head pipe/manifold flange is warped/distorted?

[BMWonly]

I just had the same (or similar) problem with my GT. I could hear a leak in the manifold area. Replaced intake/exhaust manifold gasket as well as manifold to downpipe gasket, with no success.
Took it to a muffler shop, they saw that one of the 2 downpipes right at the flange to the manifold had a crack inside.
It's now welded, installed, and quiet.

Dieter

[tomking]

My kadett wagon has a cracked headpipe but doesnt make the same sound. The Manta sounds like it is farting into a can, not that I have ever done that and know precisely what it sounds like, but that's the way I would describe it. I will look again for a cracked headpipe. If I can get to it it should be easy to weld up. Thanks.

[guyopel]

Tom
One way to check for exhaust leaks is to use a 3 to 4 ft.
rubber fuel line as a listening device ..Hold one end of the hose to your ear and use the other end to move around the exhaust sys. at gasket areas that may be leaking . HTH
John

[tomking]

Guyopel, I tried the hose trick you mentioned and it sure pinpoints the location doesnt it? It is around the backside of the exhaust manifold between manifold and engine. I am afraid it might be a cracked manifold since there is no gasket back there. Another big job now.

[BQS4]

Guyopel, I tried the hose trick you mentioned and it sure pinpoints the location doesnt it? It is around the backside of the exhaust manifold between manifold and engine. I am afraid it might be a cracked manifold since there is no gasket back there. Another big job now.

Tom;
Here's another thing to consider, it could be the gasket between the headpipe and the exhaust manifold has blown out on the back side, the side towards the motor.

[tomking]

Gene I had installed a new manifold gasket a few weeks before but that didnt fix the problem. I resigned myself to pulling the intake/exhaust manifold to fix the problem. I have never been able to loosen all the bolts on the exhaust flange to downpipe and I was dredding that. I put the Manta on my lift and went after the six bolts and low and behold all 6 came loose! A good beginning for sure! Lowered the car and drove it outside to continue. When I pulled the I/E the problem showed clearly. Although I had installed a new I/E gasket it was still leaking between the exhaust manifold and head at 2/3 position. I had torqued down the bolts so I suspected that exhaust manifold was warped. I had prepared a new homemade sprint manifold and had stainless bolts for the downpipe and proceeded to install everything. That has cured my exhaust leak and wasnt so bad since all the bolts came loose; that was the first time taking 6 or 8 apart that they have all come loose.
I will just keep the offending I/E combo together and fly cut them to true them up.

[BQS4]

Tom;
I have driven enough Opels over the years and miles, that when you have an exhaust leak that cannot be spotted, but, definitely heard, 90% of the time it's the gasket between the headpipe and exhaust manifold. It's a horrid thought trying to remove those 6 bolts, but, sometimes Lady Luck smiles your way and makes it easy. Glad you got it done!
Gene

[tomking]

Gene it wasn't the downpipe flange leaking, it was at the head to manifold gasket, on the 2/3 exhaust even though I had installed a new one a few weeks before which didn't cure the problem. I suppose the exhaust manifold was warped since it didn't leak when I installed the new exhaust manifold.