Sherl

Can someone say me whats the gasket between Exhaust Pipe and Catalytic Converter? I suspect mine is probably leaking so I would replace both the exhaust gaskets. Also is it a DIY or pay a shop to do it? I suspect the car is from California and look okay on the Cats, the bolt might be stuck deep. So.

Also can i apply a JB weld and seal it off instead of replacing the gasket otherwise?

Moarpower

Its not too bad if the bolts get stuck post cat. Pre cat is hell on earth.

jaaa

Amen. But if your car has the leaks like mine did, it was on the top side of the flange on the rear part of the cats.

Sherl

Part number for L and R gasket's then? 1998 LS400 and California if that matters

jaaa

Just a hint for when you do it, use liberal amounts of Permatex Ultra copper both before and after the gaskets. That is what ultimately stopped my leak.

Sherl

So instead of the gasket sealer I need to use this? Thank you!

jaaa

First time I did it, I bought new gaskets and put a little Permatex Ultra Copper on(still had leak). Second time I tore it apart, I reused the gaskets and used a lot of the sealer. I took pictures of the after shot if you're interested.

Sherl

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Yes and part numbers?

jaaa

On this thread around post 127 and 128 you should see pictures of what I was talking about. As to part numbers, I just went to Lexus and ordered them there. I also have a 1996 and think the numbers changed for the 1998. You could also just go to AZ. I don't think the quality of the gasket matters as much as using liberal amounts of the Permatex.https://www.clublexus.com/forums/ls-...w-owner-9.html
The reason I don't think the gaskets matter that much, is that the first time I changed out my gaskets to fix the leak- the leak was actually much worse after I had cleaned up the flange of corrosion and installed new gaskets.

Sherl

Thank you. Is installing a gasket is easy Job here? I don't have any power tools apart from a rachet set.

jaaa

Two bolts hold the rear part of the cats on both sides, so you would need to take off 4 bolts(and one in the rear if you wanted to take the Y pipe off entirely. If I remember right I had to cut off one of the bolts because I rounded off bolts on disassembly. Probably depends on how rusted those bolts are as to whether you could handle this.

Losiracer2

I have to agree with this. I think I need to go back into my post cat gaskets and add this. I just added two new rear FelPro gaskets (made in Japan) and my 99' still has a sputtering when initially started up, but when warm its slightly less but still present. I think I need to slather this stuff on to help seal the gasket better.

This stuff might be better though. The copper stuff only goes to 700F intermittent. This stuff goes to 2000F, Permatex Muffler & Tailpipe Sealer

https://www.acehardware.com/departme...4aAnoBEALw_wcB

Sherl

Does it require settling time? Like over the night before I can start using my car again.