Exhaust Leak

[eForce]

I can't seem to find my leak. I've replaced both manifold doughnuts and all smaller manifold doughnuts at the manifold. Could it be leaking at the top of the tubes near the head? Do doughnuts go up there too?

1965 Monza, 110 HP

[azdave]

The metal tubes press fit into the heads. No sealer or such is used. If they fail, the aluminum could erode away and that would cause a leak but I've never seen that myself.

Can you lay under the car while it's idling? If so, do a test by partially blocking the tail pipe (to help make the leak worse at idle). Next step is to take a long hose 3/8"to 1/2"scrap rubber hose and hold one end near your ear and move the other end around the exhaust parts until you hear the pft-pft-pft sound get much louder.

FYI...
If you fully plug the tail pipe on a well sealed exhaust system it should cause the engine to die soon after plugging it up. If it keeps running, it's a sign the exhaust gases are escaping somewhere else.

[eForce]

awesome trick. Found it. Thanks.

[cad-kid]

awesome trick. Found it. Thanks.

Do tell - Where was the leak?

[eForce]

right at the seam of the muffler on top

[cad-kid]

right at the seam of the muffler on top

Very sneaky