rubikstruck

Hey guys, long time lurker here with a question:
While installing my water pump (on an '85 22r, but that don't matter) a friend advised me to apply rtv to the mating surface on both the pump and the timing cover, in addition to using the supplied paper gasket. This is a bit of a head scratcher to me, but he is adamant on this point. I've read in another thread (of course I can't find it now...) that toyota specifically recommends against doing this (on the 3z at least) because it causes leaks! So, my question to you is basically: is it a bad idea to use rtv in conjunction with gaskets to seal something (besides stuff that calls for it like where the timing cover meets the head and such)?

Thanks for any responses!

snobdds

I used the coolant specific stuff (RTV) on both mating surfaces plus the paper gasket and I've had no leaks. Don't need to put a lot, just a thin bead and spread it evenly. Let it tack up and then do the other surface. Then just torque to spec, no need to over tighten or you will just squeeze all the stuff out.

The reason the 3rz and the 5vze do not call for RTV is due to a silicone bead already built into the gasket. The 22r(e) do not have this and thus I always use a little to seal stuff up well.

rubikstruck

Thanks for the reply!
I ended up using a small bead and spreading it out like you said, so far it hasn't leaked after about a day!
Now if only the darn thing would start

TinMan

I use ultra black, or the right stuff on just about everything. I always spread a thin layer on both surfaces with my finger. Then hand tighten, let sit for 20 min, then torque to spec. I have found that I regularly have leks were I don't use it. And never have a leak were I do use it. I have even started using ultra copper on the exhaust manifold.

Almost all surfaces will have small irregularities that paper alone may not seal up.

Sensei

Also on older engines the aluminum gasket surfaces may be pitted or scarred. The rtv helps fill these voids thus creating a better sealing surface. But only on sealing surfaces appropriate for rtv.

toyospearo

X2 I do the same as above!

fork

I use RTV for most gaskets like that too. I usually use a thin layer which not only helps to seal but helps to keep the gasket in place during install. no leaks so far, knock on wood.

83

I read an explanation once, of why "in theory" using both a paper gasket and rtv is absolutely not a good thing and will cause leaks.

But experience means more than theory, so it looks like it's a good thing to do.

snobdds

I agree theory and reality rarely go hand in hand.

Also, did you know communisim works in theory too. Just not in real life

83

peow130

Always have, and always will.
Never had anything leak from this method.

When i do it, i put rtv on the thing the gasket is going onto, stick the gasket onto it, let it tack up and almost dry, then i put rtv on the other side of the gasket, smear it over into a nice layer, then put it onto the other thing that it needs to stick to

rubikstruck

Hey all, thanks for the input! It does make sense that the rtv fills in imperfections in the casting and will provide a good seal... I guess I was just being a paranoid noob

83

This is from BigMike over on Marlin's Forum, so you weren't being a paranoid noob. But like I said, experience matters much more than theory.

"Never never never never put silicone over a paper gasket!! The silicone dries hard, and then the gasket absorbs gear oil and expands, the silicone is not able to expand with the gasket and it will leak like crazy.

It definitely can be annoying to have the gasket not stay in place, so what we do is the following:
We prefer to install all gaskets dry, but for the sake of holding the gasket in place, we will coat the transmission side with Permatex High Tack gasket sealant (http://www.neverseezproducts.com/gasketseal.htm). That way the gasket will have one sticky side that will stay on the transmission while you get the t/case into place."

Moonfish

I use high tack. I use gaskets when available. If I use FIPG, I don't put a gasket in there.