PB blasted the Y pipe nuts and they came right off from below.
But I have a problem. The connection from Y pipe to exhaust manifold is supposed to be with double threaded studs into the exhaust manifold flanges, and then nuts holding the Y pipe on.
On my truck someone used incorrectly sized bolts into the front two flange holes instead of the studs, and stripped the holes. They used nuts on the top side to hold them in.
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So I can thread in the new studs for the back flange, but on the front flange I need another solution. The old (incorrect bolts) were not even the right thread pitch, so they stripped the inside threads of the exhaust flange completely. The new studs won’t thread in.
I’m afraid there isn’t enough metal there now to even retap them to the correct size. They seem to have been widened. So I might have to go up a size.
Or replace the exhaust manifold completely.
On a related note, I have struggled solving a problem of exhaust fumes inside the truck. Maybe this front flange didn’t have a good connection and is the culprit. Maybe replacing the manifold is a good idea.
Anyone want to sell me a manifold?