I removed the muffler to replace the gaskets in an effort to rid the popping on decel. Won't re-install until tomorrow because I decided to clean up muffler apply a coat of heat resist paint. Out of curiosity I started the car with just header/exchanger to see if popping still existing - it did. Does this mean my leak is before the muffler gasket (exhaust manifold gasket) or is this typical without muffler installed . BTW - there was clear evidence that the exhaust was escaping at least at one of the the muffler gaskets as you could see black residue on the bottom outside edge of the gasket (no seal).

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Are you sure the leak isn't at the head to exchanger area?

Also, be sure you get the surfaces nice and even befoore you reinstall

I'm not and frankly thats what i'm worried about . I guess I'll find that out if I still have popping after exhaust/muffler gaskets are installed. I have cleaned up the surfaces - tx

Really not a hard job to change those. No need to worry

You definitely have a heat exchanger/muffler leak on the left gasket.

Buy new gaskets. Cheap from Pelican or AA.

Maybe you need new nuts/bolts/washers?

The popping will disappear. Never supposed to reuse a gasket, even if you use it for a week.

They crush and cause leaks after tightening down even once.

We are talking less than 10 bucks for new ones.

John

thanks john. new gaskets in hand. bill

I'd pull the heat exchangers too and change the copper O ring gaskets. Before re-installing anything carefully flat file the gasket surfaces so they are flat and clean! On the Heat changers carefully maintain the same plane of the surface. Usually all these surfaces get distorted by torqueing on the bolts over and over again until they are not flat causing leaks.
To remove the Heat exchangers spray the nuts with PB Blaster one day, then again the next day and then carefully loosen em in a back and forth motion to not snap the exhaust studs. GO SLOW! Use lots of PB Blaster to keep the rusty suckers from binding and snapping the studs...
Then pull out the copper gaskets and install the new ones and don't over tighten the new copper nuts and snap a stud.
Use all new nuts and bolts on the muffler to Heat exchanger, I like to use Stainless ones...

Great advice

and this is much harder than it sounds! I am doing the same right now, trying to remove the old shot 75 he. and replace with 74 system, but cant get these things off PB blaster and all, and i am afraid of breaking off the exhaust studs!!! Good luck with yours,

phil

I know i'll get flamed for this, but I actually put some of that high temp orange sealer on both sides of the gasket last time I did mine. Helps keep the vibration down in the joint and keeps things nice and tight. Never had a leak again from there.

Easy peasy...yeah right . I'll give it a go. Thanks for the directions