Heat riser gasket???

[NOVAZ27]

My 84 Caprice 305 has an exhaust leak around the Heat riser area. After dropping the "Y" pipe down I noticed that there is not a gasket between the top of the heat riser and the exhaust manifold. I could not find a replacemant gasket on any of my local parts houses websites. The top of the heat riser appears to be machined flat while the exhaust manifold outlet has an inner beveled edge that would accept a donut gasket. Has anyone had any experience with the need for a gasket in this part of the exhaust? I could find a gasket, FELPRO #60771, for the 85-90 CAPRICES but not the 84.
The manifold uses the two stud configuration.

THANKS IN ADVANCED FOR ANY SUGGESTIONS.

[silicon212]

No gasket needed. Just make sure the nuts on the studs are properly torqued.

[j cAT]

Originally Posted by NOVAZ27

My 84 Caprice 305 has an exhaust leak around the Heat riser area. After dropping the "Y" pipe down I noticed that there is not a gasket between the top of the heat riser and the exhaust manifold. I could not find a replacemant gasket on any of my local parts houses websites. The top of the heat riser appears to be machined flat while the exhaust manifold outlet has an inner beveled edge that would accept a donut gasket. Has anyone had any experience with the need for a gasket in this part of the exhaust? I could find a gasket, FELPRO #60771, for the 85-90 CAPRICES but not the 84.
The manifold uses the two stud configuration.

THANKS IN ADVANCED FOR ANY SUGGESTIONS.

its been a while since I did this but I thought the flat heat riser to manifold surface had a metal gasket...the flare end uses no gaskets as well as the crossover pipes.....

most likely the flare end of the cat conveter pipe is worn/flange rusted badly causing the leak...

the motor mounts if defective will effect this part ...check the motor mounts especially the driver side ....

[Blt2Lst]

Wouldn't hurt to use some anti seize on the exhaust bolts upon reassembly just in case you have to take it apart again in the future..

[NOVAZ27]

Thank you all for the replies. All the information presented was invaluable to solve the problem. My Caprice's 305 "H" exhaust did not require a gasket/s period. I used PAR HIGH TEMP anti seize on the threads. I cleaned the threads with SPRAYON BRAND RUST BUSTER while running the nut up & down a few times.
F.Y. I.
A procedure that I learned when installing the "Y" pipe is to line up the short leg first. Which in my case is the passenger side. Gently snug it up then gently snug up the other long leg side. Check the alignment then torque them down evenly. The leak that was present around the heat riser is now gone. Forget using the air impact wrench. Unless you like replacing studs. Using an air ratchet wrench with low torque is ok for speed work.

THANKS AGAIN FOR THE INFORMATION

[j cAT]

Originally Posted by NOVAZ27

Thank you all for the replies. All the information presented was invaluable to solve the problem. My Caprice's 305 "H" exhaust did not require a gasket/s period. I used PAR HIGH TEMP anti seize on the threads. I cleaned the threads with SPRAYON BRAND RUST BUSTER while running the nut up & down a few times.
F.Y. I.
A procedure that I learned when installing the "Y" pipe is to line up the short leg first. Which in my case is the passenger side. Gently snug it up then gently snug up the other long leg side. Check the alignment then torque them down evenly. The leak that was present around the heat riser is now gone. Forget using the air impact wrench. Unless you like replacing studs. Using an air ratchet wrench with low torque is ok for speed work.

THANKS AGAIN FOR THE INFORMATION

so the exhaust leaks were the result of y pipe flanges rusted out ?

[NOVAZ27]

Rust was not the problem. I had to replace the exhaust manifold a couple of years ago on the passenger side after an encounter with an object that fell off of a trailer I was following. I am figuring the "y" pipe was misaligned & not torqued evenly. When the original repair was made it was winter time and even though I was working in the garage it was cold. The original repair held for about a year then slowly started to leak. Probably from shifting around slightly. This repair seems to be holding. Time will tell. The Caprice has 324k mi. on the od. She is a road car being driven 30-40 mi. daily so the exhaust gets hot enough to burn out the water/acids etc. that cause havoc with the pipes.

THANKS

[j cAT]

Originally Posted by NOVAZ27

Rust was not the problem. I had to replace the exhaust manifold a couple of years ago on the passenger side after an encounter with an object that fell off of a trailer I was following. I am figuring the "y" pipe was misaligned & not torqued evenly. When the original repair was made it was winter time and even though I was working in the garage it was cold. The original repair held for about a year then slowly started to leak. Probably from shifting around slightly. This repair seems to be holding. Time will tell. The Caprice has 324k mi. on the od. She is a road car being driven 30-40 mi. daily so the exhaust gets hot enough to burn out the water/acids etc. that cause havoc with the pipes.

THANKS

the road salt got to my Y pipe/heat riser flanges/studs..

on replacing with new pipe found pipe not exact like old ...had to retorque a couple of times when pipes hot ..then no more leaks...

the hardest part was the stud replacing...manifold lasted the full 380,ooomi...280,ooo the y pipe failed..