<VV> Rant on RTV

[Smitty Smith]

From: Tony Underwood 
Subject: Re: HELP!... push rod tubes...
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I don't like having RTV inside an engine, anywhere, for any 
reason. That includes that blue Permeate stuff, unless it's 
smeared onto a paper gasket and allowed to cure BEFORE you assemble 
the stuff. And even then, a little goes a long way; keep it thin, 
no oozing out between the mating surfaces allowed.

Now: That being said... I have nothing against gaskets made of 
cured RTV, valve covers etc as long as they're not over tightened so 
as to crush or pinch the RTV gasket. You don't want that stuff 
floating around inside an engine.
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  Smitty says:  Tony and I have discussed this before in private posts.  Now he has made his opinion known I want equal time for mine.  First, he is right about silicone sealer on O rings.  Anyone who knows anything about O rings knows that you should put nothing on then that will interfere with their "small point contact".  Using Silicone sealer with do nothing but provide a couple of adjacent surfaces to induce capillary seepage.  After that though, I feel he gets off the mark.  RTV was developed by GE for electrical insulation and to prevent water intrusion.  It is true that the original stuff when exposed to oil or especially gas would turn into snail snot.  Today's product is a far cry from that.  It is designed to be used in the presence of oil and is even some gas resistant.  A light smear of it on mating surfaces will not fail because of oil contact.  If some squeezes out it will harden right there, and when next you pull the pan or valve cover the only way you will
 get those squeeze outs off is to tear them off.  They aren't going any place unless you remove them.  I totally disagree with the idea of applying Silicone sealer to hard surfaces and then crushing them together after the sealer is partially or completely cured.  That is just asking for some of the hardened sealant to be squeezed to the inside and become detached and cause problems.
  When clean up time comes the stuff is great.  Residue removes easily.  One of the jobs I used to hate, was removing gasket material from the block cover and windage tray.  About 20 years ago I quit using gaskets there.  Just a light film of silicone sealer on both sides and torque em down.  I have always tried as I got older to keep an open mind on things as they change.  I feel Tony and a lot of others made their minds up a long time ago.
  I guess I'd better throw up a preemptive strike on using no gaskets under the block cover.  I have read all the worry warts concerned about coefficients of expansion etc.  To them I say either the sealer is allowing the joint to slip or else the difference is inconsequential.  The only failure of the tray I have ever seen was one of the very early thin ones failed from crankshaft sonic vibration and it literally crumbled from fatigue.  OK, back to your regular programing.