My father had a mid 80's Olds and he complained about exhaust fumes in the car. He even taped over the interior vents. I was over at his place and he complained about it to me. I could hear the tapping sound and told him, exhaust manifold gaskets. He took it to several shops, they said: lifters.

I told him the gaskets were bad and leaking, evidenced by the fumes in the car. He finally convined some repair shop to fix it and guess what, manifold gaskets.

Since your car has a double firewall and rubber gaskets like my 300SE, and no gasket is perfect, I still suspect the manifold gaskets. A clogged cat would also cause your problem with a swooshing sound since the cat(s) might be clogged.

Exhaust gasses are converted by the cat from mainly CO to CO2 and water. The cleaned exhaust gasses also have a sweet smell to them. If your car interior smells sweet like that, then the leak is after the cat.

Get someone to cover the pipe outlets with their hands and check for leaks in the rest of the system.

Good luck. Report back.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.