Cork Gaskets

Coppercoat works well with cork gaskets. It helps keep them in place better than RTV. I use the RTV in the joints at the mains only with cork. If there is a metal reinforced silicone gasket for your car, that would be my choice. If not, the cork is better than plain silastic gasket.

Lugnut

The Ford dealer once used nothing but RTV on my oil pan (cast aluminum), and the oil soon looked like green algae. They said it was normal and that the oil didn't need to be changed (I changed it anyway; the new oil stayed clear). I assume that they used oxygen-sensor-safe RTV and not the kind that smells like vinegar before it cures. BTW, the cheapest sensor-safe RTV I know of is the Permatex blue kind sold at Wal-mart. It's not Ultra Blue, just regular Blue, but it is labeled as being sensor-safe.

Please correct me if I'm wrong, but I always thought that as long as the mating surfaces weren't gouged all to hell, and you got all the old gasket material off, that RTV was not necessary with new gaskets.

-phaeton

That is normally the case, Phaeton.

Plian RTV sealant with no gasket works well on flat surface pans. It is not viable where the pans curves up around the main caps with separate seals. If the Metro has a flat surface pan, I would be very tempted to use a 1/4" bead of RTV and forget the gasket.

Lugnut

This is what I did. I put a thin bead of RTV [orange] on the inside edge of the pan. I laid the gasket on top of the bead and turned the pan upside down on a flat surface [washing machine] while I prepped the bottom of the engine. Then I applied another thin bead of RTV to the gasket inside edge and installed the pan. This is on a new pan because I had a problem with it leaking before and I don't want to mess around with it anymore. So I replaced the pan and tightened it down snug with a 1/4 drive. Will this suffice? Will I have any problem with the gasket and RTV together? I hope not, it's done now. One last thing. I'm letting it set up until tomorrow 5 PM EST just to keep any stresses and fluids off of it. Thoughts/comments? Thanks.

As long as you let the RTV set up and cure before it is exposed to liquids and elevated temperatures, you should have no problem.

RTV is not something that you reassemble wet, or just skinned over, and put directly into service, if you want it to be very robust and durable.

Even the acetic acid/anhydride curing compounds are not a problem if they are allowed to cure totally before being put into service.

Some of the professional mechanics on this board have mentioned they dont have the time to let RTV's cure this way, and I can certainly understand that. But for best success, the Room Temperature Vulcanizing silicones MUST cure totally, and this can take several hours. I say 'overnight' but read your instructions carefully.

What about when the directions tell you to do just that? They tell you to assemble shortly after application. If its really necessary I will look at a tube tomorrow when I am at the shop and copy the text. Obviously filling with liquids and subjecting to pressure -- particularly in a coolant application -- is another matter. The longer the better on that one.

Don

I think I just didnt explain myself too well.

You can, and should, assemble it wet or skinned, but you should not use it, charge fluids to it, apply pressure to it until it has cured totally.

Until it has fully cured, it can be partially dissolved in oil, can be displaced by water, etc.

Some people apply the silicone, let it skin over, assemble, and put it into service. This will sometimes fail to give the desired results.

If you assemble it and let it cure in place, it is very very strong and durable.

I wondered about that.

Agreed. I like to let it sit overnight. But how important that is depends on the application. One important caveat: it should NEVER been on something like an oil pump or oil filter housing. If a little string of cured hard rubber breaks off and blocks an oil hole that's not to good. Doesn't belong in the oil pump either.

Don

Absolutely, Don. The application, as you point out, dictates to some extent the need to be judicious with curing times.

As far as the problems that can be caused by excess RTV and sloppy installation, again these are good points. This could be just as true with any hardening or solidifying gasket forming compounds, not just silicones.

I prefer not to use these compounds if I can avoid them, since some of them are so hard to clean off if you ever have to go back in.