Hello All would I be out of line to try and place red copper high temp Permatex on the exhaust manifold to head seal to ensure a good seal? (1990 22re 4runner)

 

Ultra copper works great on exhaust manifolds.

 

I tried red high temp on my manifold-downpipe connection and it simply turned to grey ash.

 

It will burn off in no time if you are putting it directly on the exhaust manifold. I tried it when I was a kid many years ago. Why do you need sealant on the gaskets? They should seal just fine with the correct gaskets & torque.

 

I used that stuff when I was trying to seal up my exhaust better. It burnt off in the first mile and stunk like all hell just farted after eating anchovies and Mexican food for 3 days.

 

Downey recommends lots of copper coat for their header gaskets. But I agree if the gaskets are good and the surfaces are good, you shouldn't need anything. Problem is Downey's header flanges are not always flat.

 

Thanks for the advice. I am trying to stop what sounds like a possible exhaust leak. Here is the video of the sound. http://www.youtube.com/watch?v=hJKve5dr2-o . I had a local shop tell me to be wary of possible piston slap. I am considering taking off all belts and removing the exhaust manifold tonight, start it up and see if it still makes the sound. FYI the video is with the truck under load. It only makes the sound underload, or on the uptake of reving the engine.

 

kinda hard to tell from the video, try having a buddy stuff a rag in the tail pipe while it's running while you listen for a leak. It will sound like a hissing sound. Now don't stuff it in there so good that it hurts something, just have someone block it off for a few seconds.

You could also get an auto stethoscope, they are cheap ($5.00 or so @ harbor freight) You can listen to the block & see if that's where the noise is coming from.

good luck

 

yea I just got back from the auto shop with a stethescope
hope it works. Thanks

 

haha, oh good, then I'm not the only one

tried it when I had my stock manifold to seal them damned 2 doughnuts... yeah, that didn't work

 

The Copper RTV can often be used between the manifold and head because the head absorbs a lot of heat away from the gasket area, even in turbocharged applications. That is not the case further downstream where the downtube(s) connect to the manifold.

The downtube on my truck(as well as a previous '94 just like it) cracked all the way around the merge. I welded the heck out of it and it hasn't cracked for several years now. The new problem is that the nuts holding it on must have annealed or worn out from being removed multiple times and became prone to rattling loose, thus causing the donuts to blow out. I eventually lost all the originals completely and replaced them with 10.9 serrated flange nuts, but some of those fell off too, as well as one of the whole damn studs. I replaced all that, added some stainless split washers, and am now reduced to checking them about every 3000-4000mi.

 

lol, bought and installed a bone-stock manifold about 3 months after I got my 91, cause the original had a crack in it

came with new studs and nuts, and I added some stainless lock-washers

I never had a problem with the bolts working their way loose, strangely though, the doughnut gaskets would blow out after a week or two... I installed, literally, 5 sets... at $2 a peice, it's not like that was agrivating me, but they can be a PITA sometimes...

after the 5th set blew out, I just said screw it and let it leak

then I bough a header to get rid of that joint there... now the header gasket that came with the header has cracked and is leaking, and a stud holding it on has worked it's way loose I just can't win...

hopefully, if the weather's nice, I'll put the new gasket on tomorrow and put a new stud in, and see if I can get that agrivating noise to go away

 

On my camaro I used the copper seal stuff on all hot side surfaces and no gaskets. (minus header to head which I am using a factory gasket which is multilayered steel from GM). Works great.

 

I have a 01 Ford f150, I noticed a small hole in my Exhaust manifold, will permatex high temp hold the heat

 

No.. As mentioned above, wrong application.

Silicone melts at ~300°, ignites at ~500°. Your manifold will see temperature in excess of 600°.
(All temps given are celsius)

 

It is probably time for new exhaust manifolds.

Just so you know, this is primarily a Toyota Truck and SUV forum.