What do you engine builders think about using copper RTV for headers instead of gaskets?



John

 

Hi John. I just used the Copper RTV on my stock manifolds and it is still setting up. I will fire it up tonight. It is very thick and I liked the application. I have a thread ""exhaust mainfold improvement"". I will let you know.
The jerks at the auto stores act like it is from mars. I asked an application question and was berated for being a stupid idiot. " You can't use RTV on exhaust manifolds, come on buddy" then I asked him to read the package "For exhaust manifolds" then he says " no real mechanic uses that crap" As I started for the door I said "must be why your working here" I think its good stuff but tonight I will light er up.

 

on my old truck, we would have to change the gaskets out ever few months, we even tried doubling them up. which helped alot, but still would eventually go out.. we use the copper rtv last time we changed them and they havent leaked any yet, and that was about a year and a half ago i think? something like that. which is a heck of alot longer then it ever lasted before

 

Lots of people use the Copper RTV on exhaust gaskets. I've never bothered although I have used in on the front and rear edges of the block in lieu of those cork intake manifold gaskets. I've also used Blue RTV with no trouble.

There is a theory that exhaust gaskets should be installed dry (at least one side) to allow movement of the manifold relative to the head as the expansion of each is different due to temperature being higher in the manifold. I tend to discard that theory as I can only see it working if the exhaust manifold bolts are left loose, and that's a bad idea.

Keep in mind the copper stuff isn't that much more resistant to heat then the regualr stuff (despite the package claims), or so some reasearch showed I no longer have the source for.

Also, despite the time to set-up as being a few hours, wait at least 24 hours for full cure before flashing your enigne up.

 

Did you follow any particular procedure when using the Copper RTV?

I had headers installed on my 360 a few months back, and notwhistanding all the claims by the mechanic they leaked from the first time I drover her. I have the 360 out and am putting a 410 in, and we are thinking about either double gaskets or Copper.

 

I never use any RTV or silicone or anything other then gaskets, on my exhaust. I hate using it period, it makes cleanup amess. It has its place, but My opinion is not on an exhaust...

I have never had them fail. I have seen stock ones fail, but they had many many miles on them, just did a chevy with over 200000 miles, his finaly failed...Broken stud bolt.( in the back of course)

My opinion is, there is no reason they should, exhaust is leaving the cylinder, and passing threw the exhaust manifolds or headers. If the gasket, blows out prematurly, then there must be to much back pressure.
suspected to small of opipes, or muffler issue's.

It is kinda like water pipe, and sewer pipe... Water pipe has pressurized water, a sewer pipe has water the flows out, no pressure..

 

Just returned from Advance Auto, and only found two hi-temp rtvs. Red was too 650º and copper to 700º. I am sure the temps will be much higher.

Any suggestions?



John

 

No, temps shouldn't be that high, especially if you only coat the cyl head side of the gasket.....hmmm....maybe on the metal side and towards the head (which may be backwards from the instructions). Don't forget, the heads are water cooled, it is only the manifold that gets very hot.

Anyway, maybe read the following thread (especailly what Stockman says in his post):

https://www.ford-trucks.com/forums/4...ld-gasket.html

 

Sorry this is off topic a little- I have never tried RTV on headers but on my big block powered boat with over the transom headers which see's sustained high RPM use- much more than most car engines will ever see- I only use header gaskets that are wire mesh reinforced. MR Gasket 5910 is the number I use and they last for several season's. Regular paper gaskets only last one season at best.

Just my 2 cents

 

The thread makes me wonder, about grade 8 bolts, and how brittle they would become, from constantly heating them up... I realize regular bolts would also be in the same heat, but Grade 8 would become brittle, good luck taken them off with out brakin um, then try to drill them??

I have heard of Grade 8 in the manifolds, or header collector, but would reccomend usein brass nuts so you can atleast torch them off, if you needed to...

I do agree with milling the manifolds... absolutly.

 

I have heard of copper RTV being used on headers. I have never tried it, but have one concern to using it. I just spent this weekend pulling my headers and changing out the gaskets with a high quality set. My question is how hard will the RTV be to scrape off the heads and headers? The old gasket material I was working with scraped off pretty easy, but this may cause some problems on aluminum heads avoiding scraping into the aluminum and gouging it up.

 

RTV is easy to remove...you can even rub it with your thumb and it will ball up and come off.

I use Mr. Gasket header bolts....I think P/N 917. For cast iron manifolds, I'd use studs and nuts. Muffler shops carry some that are an alloy and won't rust, nuts to go with them are usually brass. WARNING: Never use heat to loosen the alloy studs/nuts. The studs will twist off / shear easily with heat applied.

Grade 8 bolts are overkill for exhaust manifolds. Grade 5 probably are too, but I never go less than Grade 5 on anything to do with the engine.

Grade 8 bolts shoudn't get brittle. I think it's the so-called Grade 9 bolts that are brittle. I sort of think Grade 9 is a fictious number and not recognized by SAE.

I use Never-Seize on steel exhaust bolts, but sometimes letting them rust in place helps keeps them from coming loose....LOL.

Back to the original post, RTV can't hurt, and can possibly help, but I really dont' think you need any if you go with a quality gasket. Only exhaust gasket I ever had fail was from me forgetting to do the final torque. I did one side, and forgot the other.

 

Question is using rtv instead of header gaskets.

I have bolts.

thanks


John

 

I wouldn't use it in lieu of gaskets but I have used it with gaskets. I went through major issues with the headers on my Cougar (I won't bore you with all the details here) and since I can't get them off with the engine in the car I took many measures to make sure they finally sealed including using copper RTV on both sides of Fel Pro 1485 gaskets. I can't say for sure that the RTV was a major help but it certainly didn't hurt. I just pulled the engine oout and tore it down last week and there was no sign of any soot escaping the sealing surfaces of the heads or headers. In fact the gaskets looked good enough to reuse, not that I would. I used the same gaskets on my pickup with RTV. Two years after installation I had to remove the right header to replace the starter. Since I was in a gas station parking lot I reused the gasket without adding any RTV and it still hasn't leaked six years after that. I guess when it comes down to it I believe a good gasket and fasteners are the way to go.

 

Just tested my truck after the cure period on the RTV. It is completly sealed. What a difference with no exhaust leaks. I will use the stuff again. It was easy to use with a basic gasket. I took the truck out on the interstate and cruised at 70 for over 30 miles. Drove back roads on the way home. No issues.
Oh, I am real happy about it!