Use of RTV/Silicon with water pump gaskets????

cfitch · Sep 14, 2009

I have another rookie question. Should I use some RTV/silicon gasket sealer along with the fiber gaskets when I bolt the water pump and thermostat housing on the block of my 504 or just use the fiber gaskets?

Also the overhaul kit came with two approximately 1/2 inch copper washers. Does anyone know where these copper washers might go? Thanks in advance

Jeff Z. · Sep 14, 2009

I don't know where the washers go on that engine but my guess since they are copper they probabl go on any bolt that goes into water on the engine to seal it.
No need for silicon. Just tighten the pump down with the gasket.

charles todd · Sep 14, 2009

Three-Bond Sag Type silicone will replace about ANY gasket. Okuma, Club Car, and other OEM's recommend. It is grey and is somewhat runny, but not as bad a properly mixed J-B Weld. I used it instead of gaskets on my axle housing to differential, oil pan, and shiffter boss on my Farmall 504 and have suffered NO LEAKS in 3 years. Also used it exclusive as the sole gasket material on my 1979 C20 Chevrolet 350 valve covers, timing covers, and oil pan... Dry as a bone. Trick is to let it semi-cure before torquing down to prevent squeezing it all out.

CT

CGtractor · Sep 15, 2009

Copper washers go under the two nuts that hold the valve cover on.

NDS · Sep 15, 2009

Probaly not really needed but a thin coat on both sides of gasket will not hurt anything. I recently put thermostat in small block Chevrolet and had leak, took back apart and recleaned and inspected (everything looked good) put back together still leaked. Coated third gasket with silocone and no leak.

Anonymous-0 · Sep 15, 2009

That would "silicone" with an "e" and a long "o". This is the stuff the sealer you are talking about is made of. Silicon without an "e" is pronounced with a short "o" and is what electronic chips are made of.

Common mistake, but a pet peeve of mine.

Bill in IL · Sep 15, 2009

Never use silicone on water gaskets or any gasket. Freind of mine learned that the hard way. Put his water pump in his car filled it up and it pretty well started leaking as soon as it warmed up the first time.

If you think you need something use weatherstrip adhesive to hold your gaskets in place during assembly.

I would recommend not using any silicone in combination with any gasket. Just let the gasket do its job use the silicone where you may have severe irregularities or have to fill a hole in something.

I would may need to look into this stuff you are talking about Charles..... Have a few gaskets that I don't really don't want to have to make.

soybeanjoe · Sep 15, 2009

You can use silicone but only use a small amount, snug bolts but do not tighten, leave sit for at least 12 hrs, preferably 24hrs, & then tighten. If you use too much silicone or tighten before allowing it to settup you can "blow" the gasket out as the stuff is slippery.

My personal preference is Permatex No. 2 or aluminum paint.

Ron in Nebr · Sep 15, 2009

Not gonna argue that the gaskets alone won"t seal and work fine, but I was an ASE certified mechanic for a GM dealership for many years and I always put a thin film of silicone(put dab on finger and smear it on real thin) on all waterpump, thermostat housing, etc. gaskets and I"ve never had a problem with any of them leaking. The thin film of silicone acts more as a "glue" to hold the gasket in place during assembly than as an actual sealer, although it does make up for any slight surface irregularaties in the parts being assembled.

The one place where I WON"T use silicone is on a cork gasket on an automatic transmission oil pan or engine oil pan. On these thin stamped steel parts the silicone is just too slippery and will let the cork gasket slide out when it"s tightened down and the pan warps slightly(in a service shop setting ya don"t have time to let the silicone set and "cure" for several hours).

That being said, both with or without silicone will work fine in a waterpump application, whichever way the installer is more comfortable with. Just don"t overdo the silicone.

cfitch · Sep 15, 2009

Thanks for the correction.

Hobo,NC · Sep 15, 2009

Ron thumbs up!,,, folks that have to warranty their work and do the do overs for FREE understand what you say,,, folks that deal with sealing issues learn to use sealers correctly (refer back to the do over for free) them that don't work with sealing fluids never will get it.
thank god Cork gaskets are a thing of the past in our line of work.

One reason I use a thin smear of RTV in this application is if I have to do a do over it makes the removal of the old gasket EZ.

When work'n a Farmall and a cork gasket is called for it stays in the box,,, I will take my chances with RTV,,, the good chit ultra Grey

Use of RTV/Silicon with water pump gaskets????

cfitch

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Jeff Z.

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charles todd

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CGtractor

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NDS

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Anonymous-0

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Bill in IL

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cfitch

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