Just finished up my valve stem seals on my 85. Went with the advice of a few that said don't use gaskets, only RTV and not too much.
Well I guess I listened too well and probably didn't use enough as both leak pretty badly now
Just what I feel like doing again.

 

I've never substituted RTV for a "gasket application" unless it was no longer available. I've seen it done a multitude of times and generally there's been issues.

 

here's where I got my "information"
http://forums.corvetteforum.com/c4-g...placement.html

 

I've also seen guys saying they used just RTV posting on here a few times, but have never agreed with it... If you wanted to put a little RTV on the gasket to help seal, "maybe" but straight RTV, ..It may work sometimes, but definitly not all the time..The biggest mistake some guys make it tightening the valve covers down to tight. It warps the gasket... Go down till they just start to compress the gasket, , then a tad more, you can always tighten them up a little more it they leak......WW

 

off to the store and a couple hrs work tomorrow I guess

 

One thing I have seen work fairly well is to use RTV or some other sealant to secure the gasket to the valve cover,( valve cover must be clean and dry) then put the valve cover onto the head and tighten..The only thing I've ever used straight RTV for is the china walls on our engines, but "The Right Stuff" works better........WW

 

Heard someone say to do that and leave overnight. thanks

 

I don't have an '85 FSM but I do have an '84 and it does certainly call for RTV. Does your '85? Does it make a difference in the product? Maybe. Whose product did you use?

 

http://shop.advanceautoparts.com/p/p...ontent=general

 

sorry to hear the RTV didn't work out for you - it's a bummer you have to go thru the VC thing a second time. most likely, I was the forum member that recommended the RTV, but I must say, I have used it in the past, without issues. it is very important that you follow the correct procedure for it's application. it is the only method as called out in the FSM.

here's my quote from the referenced thread -

I should have noted to "let it cure 24 hours BEFORE starting the engine"

note - there is a groove around the perimeter of the VC's flange surface. follow that groove when applying the bead of RTV, especially the bolt holes.

again, sorry to hear you have to go thru this a second time. it sounds like you may go the gasket route this time. if you do, the 85's VC's are not designed for gaskets, so my may have to use a gasket "tack" product on the flange. on my 90, I used permtex, high tack, spray-a-gasket sealant, #80064, along with the fel-pro gaskets. it works like a mild contact cement that holds the gasket in place while installing the VC. basically, spray a couple light coats on the VC flange, and one side of the gasket. let it set for a minute or so, and assemble.

something went wrong with the RTV application, and I'm kind of curious what happened. anyway, good luck either way you go. if you can, post a pic or two of the area where your RTV seal was leaking. if the RTV peels off with much trouble, most likely, the flange surface was not clean. ???

 

may be a stupid question, but which side of the gaskets does the RTV get applied to?

the cover side?
the engine valve side?
or both?

 

I've always used FelPro gaskets and never a leak...from the gasket.


When doing the china walls, it's also important to dimple/roughen the two surfaces and to drop the intake straight down with not movement after it touches the RTV.
Once torqued, in proper sequence & steps, do NOT start the engine for at least 24hrs; I let it stand for a day or two just to be on the safe side.

I've not used any RTV on a FelPro gasket as I trust FelPro to do the job of sealing.

 

I called an old friend and he mentioned the use of the RTV and mentioned no problems. He mentioned many people were inclined to over-tighten them and it seemed to him that the same techs always were the ones that had issues.

He mentioned that he usually had a couple or three additional cars in the stalls so he never had issues with letting the RTV "set-up" somewhat before installing the cover. I mentioned the tightening spec in the '84 FSM and he said "never paid attention but they were certainly never over-tightened in his mind". I'm sure everything was "clean" - he was meticulous.

He mentioned he'd do RTV.

The Permatex "usage chart" is interesting. It certainly wouldn't seem to be necessary for so many products that mention the same sealing "functions".

http://www.permatex.com/images/resou...erSelector.pdf

I was trying to find a Permatex recommended for the GM # 1052366.

 

not trying to get into a pissin' contest here, but the only time it doesn't work is from the improper use or application of the product. I'm not flaming anyone that has had issues. let's face it, we're sealing two flanges that is not under (oil) pressure. if you can seal the china wall(s), there is no reason you can't seal the VC's.

this is the exact product I used on my 85.

 

here's one problem for using fel-pro silicone gaskets on an 85's VC. the 84-85-E86's VC are not designed for a gasket, whereas L86-91 are. on an 85, there is only a partial lip that might hold a gasket in place - it does not run the full perimeter of the VC's flange. (fel-pro) silicone gaskets somewhat have to be stretched to conform to the flange - not much, just a little. even using a dab of RTV to secure the gasket, what's going to happen around the corners where there is no lip? it is not the same for VC's used on aluminum head, center bolt covers. here's a pic of an 85's VC flange - nothing to hold a (silicone) gasket from contracting in that area. I guess you could use a cork, or cork/rubber gasket, but that's so old school.



I've used fel-pro silicone gaskets on aluminum head L98's without issues, but on an old iron head, I still stand by the use of RTV silicone.

 

no idea what I did wrong. I did not start engine for a day

 

I wouldn't use RTV to hold a gasket, I use -



I spray a coat on the VC flange, and a coat on the gasket, and assemble. I don't use anything on the gasket-to-head surfaces. BTW, I only use this with aluminum head small blocks, and fel-pro silicon gaskets.

 

Joe, To be honest I have never read the FSM on the earlier cars (84-85), I would never have imagined that GM would seal a valve cover with only RTV, especally since GM cars in earlier years used gaskets successfully ,but this wouldn't be the first time the engineers at GM screwed up ......Im always learning somthing new on this forum.... Also , Im pretty sure you would win the pissing contest anyway , at my age my shoes would just get wet.......WW

PS. Could someone with a 84-85 use a newer set of valve covers with a gasket on these heads, would they fit the iron head and work properly??

 

I've have used FelPro gaskets and never a leak...from the gasket.

I used the FelPro rubber gaskets on my 85 2 years ago, I think, perfect...dry as can be. Before that I tried a $12.00 black rtv, and it leaked.
Paid like $40.00 for the FelPro. I think I had to buy new bolts about 1/4" longer because the rubber made it thicker. They come with these steel long washers that you cannot use on this valve cover.
Yes, when you do them a couple times the way "the manual" says, and they leak, you will buy these, put them on, and you won't have any leaks...

 

Three years ago I did the valve cover gaskets on my 84. It had cork gaskets on it that had been tightened down to the point that there was nothing left in spots.. Got a set of Felpro rubber. Once I refinished the magnesium covers, I applied a film of Permatex to the covers and applied the gaskets to them. (One thing I learned when I finished cleaning up the covers, clean up the dust before you do any grinding.) I used the rtv because of the fun installing the driver side cover.. Still as dry as when I put them on, about 6k miles later..