Headers - Silicone gaskets?

[-Nemesis-]

I've been chasing my tail with an air leak since fitting my new headers (twice.) I've tried the composite gaskets that came with them, and the old stainless Toyota ones, though the OEM ones are dirty and a bit bent at one corner.

Instead of shelling out the big bucks for new ones; Does anyone know how well it would work just using the good Permatex Copper Silicone which is designed as a high temp gasket replacement? Without using any other gaskets. Or would I be better off fitting the steel ones with the silicone to hit any gaps?

 

[stevechumo]

I've been chasing my tail with an air leak since fitting my new headers (twice.) I've tried the composite gaskets that came with them, and the old stainless Toyota ones, though the OEM ones are dirty and a bit bent at one corner.

Instead of shelling out the big bucks for new ones; Does anyone know how well it would work just using the good Permatex Copper Silicone which is designed as a high temp gasket replacement? Without using any other gaskets. Or would I be better off fitting the steel ones with the silicone to hit any gaps?

I've been told by a guy from www.turbocity.com that it works.

 

[Zuffen]

I suspect your headers aren't flat along the mounting flange.

Why not run a straight edge over them as Toyota MLS exhaust gaskets are pretty good at sealing warped headers.

If one pipe is low (and this is most likely the problem) you can try to straighten it or add gasket material to try and fix it.

 

[-Nemesis-]

I've refitted since this question with the steel gaskets and copper silicone, the noise has resurfaced again already. I also think the manifold flanges are warped.

Do you know of anyone in Syd who can pressure test headers (off the car)? I think there may be more leaks around some welds too. I guess you get what you pay for after all.....

 

[Zuffen]

Who built the headers?

 

[-Nemesis-]

They're from the states, made to suit a Tundra. Brought here and modified by Venom in Qld to suit the 4Runner/Surf conversion (to clear the steering column.) They certainly look the goods.

He's happy to look over them, but he's in different state from me and without the headers in my car I have no transport

 

[gloverman]

I see this all the time with cheap stainless turbo manifolds. I have seen them up to 3mm of bend in the mounting surface. We always machine them before fitting. Listen to Rod - check the face for warpage. Silicon with a MLS gasket is not a good idea as it is differcult to get the silicon between the layers to seal it all up. To get them to seal you will need clean surfaces , flat surfaces , good gaskets (my choice) or good sealant and good strong bolts , flat hardened washers ( spring washers are bad on exhausts) and do the bolts up nice and tight. Good luck

 

[-Nemesis-]

What sort of noise can be expected through headers, compared to the cast manifolds?
My engine had no audible shim noises as I adjusted them late last year. Should the valvetrain be almost intrusive of the note from a 3" exhaust it's that loud? Or is it more likely the small weld leaks i'm suspiscous of? I think its more of a tftftftft type sound than a ticketytickety heheh...

 

[stevechumo]

What sort of noise can be expected through headers, compared to the cast manifolds?
My engine had no audible shim noises as I adjusted them late last year. Should the valvetrain be almost intrusive of the note from a 3" exhaust it's that loud? Or is it more likely the small weld leaks i'm suspiscous of? I think its more of a tftftftft type sound than a ticketytickety heheh...

If the headers leak, it'll sound like tftf....I just had that problem fixed so I know how it sounds like.