Proper Header Gasket Sealant - from where?
 

Anyone know where I can get the right gasket sealant for re-attaching my headers? None of the stuff from Halfords tolerates more than 350C which is useless for our cars.

What headers do you have? If standard single scroll Subaru ones, the right gaskets are the solid ones you can buy from main dealers, and any number of other places.

It's high temperature sealant 'gunk' I'm after for between the headers and the exhaust manifold. not gaskets themselves.

Do NOT use gasket sealer with turbo cars at all. The stuff goes rock hard, then little bits of it go whizzing through your turbine blades.

Why on Earth would you require this???

Brand new genuine header gaskets will do the job as it did leaving from factory..

Providing somewat decent respectable headers....

If ebay jobs and you've already fitted with gaskets and blowing well then come back to cheap headers...

When it comes to sealer my opinion is if it did't leave subaru with sealer in this area of the car why are you looking to use it.....

header gaskits are fine.. i re-used mine when i had my headders off to port and polish them!

try some blue tac if you not going to use gaskits, you will have the same effect!!!

Ok I watched the Subaru engineer put some gunk stuff around the headers before they put them back on the car on two separate occasions. I'm going to assume, no offense, that they're the experts so I'm going to do it their way. So can someone PLEASE tell me what they're using?

Use that sh*te at your peril. There's a few people posted on here that know more then ANY main dealer mechanic and by that I mean people with over 25 years of building motosport engines and one in particular that churns out plenty of 500+bhp scooby engines. Heed their advice!!!

Particulalry the part where it's stated that bits of this sh*t will break off and go through your turbo. If that happens at best it will cost you a turbo at worst it will cost you an engine.
Buy proper gaskets they will do the job perfectly regardless of what power your putting out!!!!!

I would also add that I've seen some main dealer mechanic working practices an they were dreadful. They dont know best at all!!!!

Ah, assumption, the mother of all f**k-ups. I think you can assume pretty safely that Alan is much more of an expert on the proper building of Subaru engines than your common or garden garage mechanic - Subaru dealer or otherwise. He's perfectly correct; putting liquid gasket on the pre-turbo side of the exhaust is a dull idea.

Are you sure the engineer wasn't putting anti-seize compound on the studs? If you're sure it was sealant on the mating faces, then it is correct to assume that these particular "engineers" are far from experts.

The obvious answer in these circumstances would be for you to phone the garage and ask the individual(s) concerned what they were using.

- Never thought of that ;) Take your time....

This guy has built race engines for a long while and also has an excellent reputation in the Scoob community, however he shall remain nameless since apparently my eyes deceived me.. Suffice to say I'll go with the consensus and not use any.

Hello,

Actually it's my car we're discussing, though the same procedure had taken place on aXeL's car a few weeks prior.

The headers were in 3 parts having been ported and were being put back on the car. The standard gaskets were still in place but the chap used some sort of white sealant 'gunk' on all the joins before re-attaching to the car.

Niether of us considered this anything other than the normal way of doing things, having no experience at removing/refitting headers ourselves. I did comment at the time (to aXeL) that you'd have to be damn careful with that stuff as you'd not want it sucked through your turbo. I had faith that the technician was doing a good job based on his past work and reputation.

Members comments here warning against this practice do make perfect sense, however I do find it odd that a very well respected and experienced independent Subaru technician would make what appears to be such a novice mistake.

It's very likely that the headers will be off again at some point as we both feel that there's more to be had from porting. We're now more confident and feel we can undertake the removal and re-fitting of the headers ourselves which we'd previously left to the Subaru tech - hence the query regarding the 'gunk' he used, assuming this to be part of the 'proper' method.

So, bottom line, when refitting the headers in the future we'd simply ensure that all contact surfaces are clean with no need for any sort of gunk?

Cheers,

G.

All you need is when that stuff is squeezed between the two faces a big lump of it squeezes inside of the headers. Eventually this blob (probably a couple of mm in diametre) hardens, gets brittle and eventually breaks off. It then gets sucked through your turbo which will be spinning at well over 100,000 rpm Imagine the damage that's going to cause. Your car, your money, your choice.

...thinking I might pull 'em off again and give them a clean to be sure. I can see how this could be a definate bad thing! Didn't think to comment to the tech at the time as he had my trust. Certainly taking on board what you're saying though dazdavies, cheers for your input.

Cheers,

G.

So there goes my theory (hope!) about it being anti-seize. As a matter of interest, did your man use this gunk in addition to regular metal gaskets, or instead of them?

Either way, whipping the bits off and making sure the mating faces of the joints are clean wouldn't be a bad idea. If the car's been started I'd probably have a look down the pipes with a torch too to make sure nothing's already made its way along.

At end of day different mechanics have different ways of doing things and this chap's obviously got his own ideas. May be that he's "used this stuff for years and never had a problem", but the bottom line is that Daz's comments are bang on. Using this stuff is asking for trouble on a turbo car, and provided your gaskets are in good nick you simply don't need it to get everything sealed.

Some aftermarket gaskets are toilet btw, the cheap single layer stamped ones that are around are a complete waste of money. If this is what you've got, it's worth getting some real Subaru ones.

I suspect the guy was using silicone based sealant which would just melt if it dropped into the header.

Hi,

In all honesty not at all sure what the gunk was, it could well be a silicon based sealant as Simon suggests. If that simply melts then maybe not such a problem, still anything remotely solid hitting the turbo, even if melted, doesn't sound healthy. Note: the stuff appeared to be a white, rather thin and slightly oily looking paste, though I didn't get a close up look at it.

Splitpin: to clarify, all existing metal gaskets were in place, the gunk was added in addition to these.

I freely admit that this sort of thing is new to me. My plan was to let the garage take off the headers first time so i) I could see how it was done, and ii) If there were any problems (siezed bolts etc., which there were) then it could be readily resolved. Having the garage refit them afterwards having checked my porting efforts was also part of the plan.

I'll have a word with the tech next time I see him and query exactly what he was doing and what it was he used - maybe things will make more sense then.

Cheers,

G.

That sounds a lot like regular Holts-type exhaust paste, which is the type that dries solid and cracks.

JGM may be right about the composition of this stuff, but even if he is, it still doesn't make sense. As you already understand, material of any sort making its way through the exhaust system is volunteering for trouble.

Aside from anything else, None of these compounds will properly withstand the temperatures on the inside of the manifold (as Axel found out before starting this thread) so on that level, they're useless. On the other, you don't need them to seal the system up, the gaskets alone are fine, so they're useless and unnecessary.

You seem to be panicking over nothing imho.
You dont want silicone sealant in the engine but it is used throughout.
Little is fine etc.
Actually the exhaust gas gets v hot but the flanges / gaskets are considerably colder and will not melt silicone sealant as I have tried it on my own car on stubbon header leaks.
It was intact after 20k miles

the stuff is called three bond and is available from Subaru.
It's now only available in big tubes so costs plenty and there are a few versions so research which one is right.
Its a liquid gasket paste and its the same tackle thats used on engine builds and as long as its used sparingly no one complains about the block faces.
Sure if you put it on with a spade then its going to squeeze out, but a thin smear thats well back from the port? come on

http://www.wurth.co.uk/catalogue/pdfs/UK-CD_05_2016.pdf

Although usually I've been known to use Wurth Silicone RTV (OS sensor safe).

Use sparingly, your not icing a cake! ;)

Threebond goes hard enough to cause catastrophic damage if it goes through a turbo.

Three bond is good for flat surfaces not patterened ones like exhaust gaskets unless of course used in quantity which of course would cause issue.

I would NEVER use ANY kind of sealant pre turbo full stop!!

Sure I understand Daz, but I was letting the OP know the right tackle to use if so required.

I am currently porting a set of standard headers. I am in the process of flatting all the gasket faces to within a couple of thou and plan to rebuild the cross section part without any gaskets but with a very thin smear of sealant. If used sparingly I don't see it being a problem.