Is there a hi-temp expanding foam on the market?

Hello, I have a small hole in the exhaust manifold right where it attaches to the engine -- actually a small piece of the gasket is missing. There's a little space in there that would seem ideally suited to accept a dollop of foam. The foaming insulation at the hardware store can only deal with temps below

200 degrees. Is there anything out there with a higher temp rating? (JB Weld works okay, but doesn't seem to last) Thanks!!!! Fred
Reply to
Fred Mann
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Anything but replacing the gasket will be short-term.

Reply to
Brent P

Reply to
dave AKA vwdoc1

What Brent said. If the manifold is warped it should be surfaced, or if you're chea^H^H^H^Hfrugal I have heard of people using fine solid copper wire to "o-ring" the gaskets.

nate

Reply to
N8N

No. A foam would not work well over a wide temperature range, because the gas inside the bubbles would expand and contract a lot.

You might consider red RTV, but really the solution is to replace the gasket and do it right.

--scott

Reply to
Scott Dorsey

Unfortunately, everything is so rusted that it would be a massive undertaking to do it right. Not worth it to me. I may try the red RTV though. Thanks!

Reply to
Fred Mann

If it's severely rusted, any filler you put on is going to adhere only to the rust, not to the metal underneath. And the rust is not a solid substrate and will not hold it on very well.

That is part of why the JB Weld is not working.

--scott

Reply to
Scott Dorsey

Start soaking the hardware with penetrating oil now (NOT WD-40) and invest in a MAPP torch (or oxyacetylene, if you think you might be doing this a lot.) also some 6 point sockets and bolt-outs if you don't have them.

Is the manifold held on by studs or bolts? If studs, run a die down the threads before you try to remove the nuts. Use the die "backwards" so it cleans the threads right down to the nuts. If the mfgr. of your vehicle was throughtful, they used copper or brass nuts which will burn right off with a hot enough torch without damaging the studs.

nate

Reply to
N8N

"Fred Mann" wrote in news:hZ0Vj.34898$3v1.19189 @bignews3.bellsouth.net:

the only way anything will hold is to get it into the crack. JB weld will be your best bet, if you can get a vaccume in the exaust using a vacume cleaner or better a vaccume pump and pull the stuff into the crack using the internal vaccume. anything else is a waste of time. (other than the correct fix of course.) KB

Reply to
Kevin

Furnace cement ought to work. Get it from a place that sells wood stoves. Follow the instructions for filling cracks. Give it a full day to dry. You have to make sure you get all the moisture out before you get the temp above boiling or it will crack.

-jim.

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Reply to
jim

Reply to
none2u

I just noticed that this was posted to the VW group - what kind of car are we talking about here? This might be the excuse you need to swap to a dual outlet manifold/downpipe combo if it's an A1 :)

nate

Reply to
Nate Nagel

Yes I hesitated to offer the advice because it probably won't work if not done correctly. Furnace cement will definitely take the heat - a lot more heat than a car exhaust usually gets. And it expands at the same rate as iron so heat and expansion aren't a problem even if you get the exhaust cherry red. It won't work on tin exhaust parts that flex but for filling a crack where it is rigid and there is no flex it shouldn't be a problem. Of course there is a bit of skill to applying it correctly so that it adheres and locks itself in. It won't work on furnaces and stoves either when not applied correctly.

-jim

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Reply to
jim

I think I'll try this next ... if there is a "next" . I JB welded it a few days ago ... maybe it will hold more than a few months. I don't drive that much. And by the way, the car is a 1983 VW Rabbit GTI. And the rust problem is limited to the nuts and bolts - the manifold seems to be fine. The nuts are starting to look like something off of an excavated sea wreck. I don't think I have the tools or patience to do it right. Thanks again for all of the help!!!

Reply to
Fred Mann

HEAT is the fastest way to attack those nuts. Sears sells some "rounded-nut" sockets that should work for you.

If you remove the intake manifold, that should give you more room to do it above the engine. ;-)

Some shops can do this for you and they won't charge that much. I personally like the studs replaced if they are too horrible. And install new brass self-locking nuts. JMHO

Reply to
dave AKA vwdoc1

JBWeld will not handle the heat. Period. They explicitly say on the package not for exhausts and that its only good to 500 degrees, and honestly, I don't even believe that. The exhaust there is probably closer to 1000 degrees. There is a product called "Hi-Temp Lab-Metal"

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which is supposed to be good to 1000 degrees. Honestly, even that may not be enough. As with anything, it is strongly recommended the surface is clean, dry, oil-free, and sanded so it is rough to promote adhesion. They also claim you need to slowly heat it to 425F and then keep it there in order to reach the claimed 1000 degrees. I think you might stand a chance of doing that with a heat gun. I think using the engine to do it would be unwise.

(Disclaimer: I am in no way associated with Alvin Products or any distributor of it. I have never seen, much less used one of their products in person. In short, I'm not endorsing its use, only pointing out its existence)

Reply to
<blah

the easiest and best way would be remove the head and then do the repair. So much faster...

Reply to
Lost In Space/Woodchuck

The red high-temp RTV works on exhaust manifolds. It survives the heat. However any exhaust gasket repair like that it won't stay put for too long.

Reply to
Brent P

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