Headers - Chasing the leak

[-Nemesis-]

Update, see latest post


I've been chasing my tail with air leaks since fitting my new headers (twice) on the 1UZ. 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 (in there now.)

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 as a back up to hit any gaps causing that annoying tftftftf sound?

[Harb]

Yep, we used to use the Hitemp stuff......red oxide in color on Nascar headers that would glow red hot , and never once had a leak......go for it

[Harb]

Oh yeah, no gaskets..... nothing just Silastic

[-Nemesis-]

Ahh that's good to hear. Do you use a heap of it around each exhaust port or just run a bead around the outer edge of the manifold plate?

[Harb]

Try you best to stop it heading into the exhaust port....shame to upset the flow in that area, but sort of smear it so its thinker towards the outer edges if you know what I mean......
Then make sure you let it cure before you start her up and blow it out....
It ends up looking a bit messy, but as soon as it drys , and after a run, a screw driver round the outer edges will clean up the excess

You won't have any probs, as long as the Header flanges are not 1/8 inch away from the head in places

[-Nemesis-]

Thanks for the tips mate. By cure do you mean leave it a day or so before starting?

[Harb]

Might not take a whole day, but the longer you leave it the better..... if you need to use it, let it idle for a while to get the joint hot and it will soon go off no problem...... should be right by the time you get to the first set of lights...... then you can tromp it

[want33s]

Lots of cars don't use a gasket on the exhaust manifold at all.... EG:253 & 308 holdens.
If you have the head and extractor face machined you don't need a gasket.
Usually just the tinfoil type gasket will do but the pink paper type are better if you can get them, especially for extractors.
If you have persistent leaks then your extractor face is probably warped.

**Don't use ANY silicone on an exhaust flange on O2 sensor equipped cars unless the silicone manufacturer states it's OK.**

[Harb]

yeah the silastic or permatex brand stuff is marked O2 sensor Ok on the tube....well the stuff I have is anyway, but it is worth reading the tube to make sure, they would make cheaper versions I would recon

[chunks]

Have you checked the face of the headers with a straight edge? They might be slightly warped and need machining.

[PGS 4WD]

Use permatex ultra copper as it is o2 safe and higher temp.

Joel

[CRUSHU]

[quote="want33s"]Lots of cars don't use a gasket on the exhaust manifold at all.... EG:253 & 308 holdens.
If you have the head and extractor face machined you don't need a gasket.
quote]

On 253 308 304 and efi Holdens, you SHOULD run a gasket with extractors, but NO gasket with manifolds.
the extractor flange is not thick enough to prevent warping, wheras a manifold would take quite some heating to warp.

[-Nemesis-]

Have you checked the face of the headers with a straight edge? They might be slightly warped and need machining.

That's my main concern and will check today. I have no scientific tools though. Is a flat bench or a solid spirit level enough to find a warp big enough to cause a leak?

I've got two tubes of the Copper Permatex ready to go. Just gotta get into it, half the nuts can only be accessed with the open end of a spanner, about 1/8th turn

[-Nemesis-]

Well it's heaps better, but i'm sure they're still leaking. If there's no evidence of valve train noise in an engine, then after fiiting extractors it shouldn't be so loud that its louder than the engine almost hey? I'm thinking they're still farting a bit.

When I had them out (I had to rush to re-fit them to get to Rover Park) I put the extractors on a tile in my house (1 tile is bigger than the whole manifold flange) and on both of them they could be rocked from side to side. The middle section (middle primaries) seemed higher than the outsides on both header flanges, they could be rocked by about 1mm towards either end. Does this mean they're both warped?

Can anyone suggest where I can take these bloody things (Sydney - West) to get them totally checked out? And get the faces machined etc.....
Can they pressure test headers?

[Harb]

yep they can.......pressure test the that is.
Even someone with a modded radiator pressure tester and a spray bottle of soapy water could rig up something....

As far as machining is concerned, any half decent engine reco place with a surface grinder should make short work of that.

Having said that 1mm is not much, and I am suprized the bolts didn't pull it straight and tight.

Harb

[-Nemesis-]

Well I think it'd be closer to 2-3mm now that I think about it. Could easily rock them side to side and they'd bang the tile....

Though i'm not convinced it's the flange totally. I found some leaks in the primaries which a shop hastely tried to fix. There's a chance they're leaking elsewhere.

I guess I could try the stethoscope hose trick.

[shakes]

Have you checked the face of the headers with a straight edge? They might be slightly warped and need machining.

That's my main concern and will check today. I have no scientific tools though. Is a flat bench or a solid spirit level enough to find a warp big enough to cause a leak?

I've got two tubes of the Copper Permatex ready to go. Just gotta get into it, half the nuts can only be accessed with the open end of a spanner, about 1/8th turn

use your straight edge(make sure it's straight), and with your shed as dark as possible shine a torch up from behind it, any major hole's will show up with light coming through the gaps.