Engine heat melting exhaust gaskets

[pawnthatdude]

Hi all,

I've got an 97 FZJ80 with 188k miles which is fairly new to me. About 4 months ago, I got a exhaust leak in both of the front ends of the Y pipe. The PO had a custom exhaust setup, and I took it to Boulder Muffler to have it looked at. He said the gaskets and flanges used were not the right ones and were bound to fail. He replaced them with the correct design for the application. Then recently, I started hearing (and smelling) another exhaust leak. I took it back, and it had melted all three gaskets on the Y pipe. He replaced them all for free.

I don't think this is a problem with the exhaust, so I am looking for reasons why the engine is either running way too rich or way too lean.

Some obligatory Mud research has pointed out a number of causes, but I am not really sure where to look first.

Some maybe relevant info:
I always run 87 octane gas. I mostly drive it around town and up and down a steep canyon road where I live, and I get 10-12mpg.
No CEL ever
Starts up easily and doesn't run rough. Idle has a very slight rumble every few seconds at a stop light.
No problems with loss of power anywhere in the RPM range.
Temperature gauge always in the center, even on a full day of driving.
I don't believe the HG was ever replaced.
The exhaust leak smelled like exhaust + fuel.
No other weird smells now that it is fixed again.
During the original exhaust leak, the passenger floor board would get noticeably warm. Enough to keep a burrito warm on a long drive. Even when it wasn't leaking, if I drove for many hours in moderate temperatures, the floor board/right side of the center hump would get a little warm.

Any advice would be helpful.

 

[Tools R Us]

Incorrect flanges, those are known to be problematic.

 

[Heckraiser]

You want a toyota exhaust gasket, they had them in stock at Boulder Toyota a couple weeks ago, if not, they can get them in a day or two. It is a round metal "donut" style gasket with crushable material in the middle. Anything else will eventually fail.

Your temperature paranoia is unwarranted, these are always super hot, and we all have the "heated passenger floor" luxury feature.

Boulder muffler, that brings back memories. They helped me to get my '84 pickup to pass emissions almost two decades ago before I just gave up and started registering my trucks in the mountains

:edit: wait, not sure if I read your post correctly... is your y-pipe also custom?

 

[inkpot]

I would tell Boulder Muffler to fix THEIR problem!

 

[pawnthatdude]

Incorrect flanges, those are known to be problematic.

Interesting. Do you have any more information?

You want a toyota exhaust gasket, they had them in stock at Boulder Toyota a couple weeks ago, if not, they can get them in a day or two. It is a round metal "donut" style gasket with crushable material in the middle. Anything else will eventually fail.

Your temperature paranoia is unwarranted, these are always super hot, and we all have the "heated passenger floor" luxury feature.

Boulder muffler, that brings back memories. They helped me to get my '84 pickup to pass emissions almost two decades ago before I just gave up and started registering my trucks in the mountains

:edit: wait, not sure if I read your post correctly... is your y-pipe also custom?

I believe they did replace the gasket with the type you are describing. He never mentioned it being Toyota specific but it's exactly what you describe.

The Y pipe is custom, built by a shop elsewhere in Colorado.

I would tell Boulder Muffler to fix THEIR problem!

I don't think this is their problem. I had the original leak before I even brought it there. I paid a very reasonable amount for the first gasket and flange change, and he just replaced the gaskets again totally for free. If the flanges are wrong I am all ears, but the shop is obviously not trying to scam me by doing free work.

 

[danthman114]

you can find Toyota ones on amazon for a decent price... its where I got mine

 

[Heckraiser]

The Y pipe is custom, built by a shop elsewhere in Colorado.

.

This could be your problem.

 

[inkpot]

Interesting. Do you have any more information?



I believe they did replace the gasket with the type you are describing. He never mentioned it being Toyota specific but it's exactly what you describe.

The Y pipe is custom, built by a shop elsewhere in Colorado.



I don't think this is their problem. I had the original leak before I even brought it there. I paid a very reasonable amount for the first gasket and flange change, and he just replaced the gaskets again totally for free. If the flanges are wrong I am all ears, but the shop is obviously not trying to scam me by doing free work.

If a new gasket and flange set did not fix it for the long term on the first attempt, then I would not expect just replacing the gasket again to last any longer than the first new gasket set.