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Gasket confusion (UPDATE: Gasket has been exonerated...)


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8 replies to this topic

#1 Ryker

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Posted 19 August 2005 - 10:58 PM

Alright, I've read conflicting things regarding gasket installation. The gasket for my water pump recently ruptured... I pulled the pump, bought a new gasket, and installed it using "Ultra Black" RTV silicone. Inside of a week the new gasket had ruptured. I've since checked the service manual for instructions: "Replace the gasket with a new one." (This is an '88 GL wagon.) Hmm... good. It doesn't say anything about using RTV; however, threads on the board have suggested doing so (and, for all I know, it is implied in the manual). I used a razor to scrape clean the contact surfaces... Should I also use brake cleaner? How say you to using RTV?

Thanks in advance!

Ryan

#2 Numbchux

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Posted 20 August 2005 - 12:13 AM

well...my haynes/chiltons manual said use a 'gasket remover tool' (or something like that) to take off the gasket, and RTV... I used a big flat chisel and some block cleaner, let it dry, and put RTV on it, and I think it leaks a bunch, but I'm too lazy to really do anything about it, I just keep adding coolant, and it keeps cooling...

#3 soobscript

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Posted 20 August 2005 - 03:31 AM

I don't know about the RTV. I'm about to do mine and was planning to use a gasket. After getting both surfaces completely clean (scraping and solvents), I always wipe them down with brake cleaner (on a clean, lint-free rag) and watch it evaporate right before putting the gasket on.

#4 sregor13

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Posted 23 August 2005 - 08:57 PM

Blue RTV Sealant is recommended. Clear works but just use the blue if you can. If you use the Gasket Scraper ( I did because it was the same price as a Jug of Coolant) then scrap away the old gasket the best you can. I then would clean it with your usual cleaner. I used brake cleaner because it was ready at hand. Then wipe and let dry. Put a bead on the water pump itself and let it dry for just a second, then put on your Water Pump Seal and hold it there until the room temperature vulcanizing sealant starts to vulcanize (or whatever it does) and holds the gasket in place.

Then throw another bead on top of the gasket and slap the Waterpump on. Get all of your bolts (I think there is five), dabbed with the RTV and put them in semi-tight, let them sit for ahwhile before the final torque. If you have the Metal Coolant tube coming out the the side of your WP then put a new O-ring on there (apply small amount of coolant to o-ring for lube) Liberally apply RTV to the tube. Slap in the tube and bolt it down. Wipe away excess RTV from edges of waterpump. Let the RTV cure for at least 6 Hours, 24 is better.

When I bought my WP on Ebay for like 20 Dollars it came with the Water Pump, the Gasket and the O-ring. It has been working great.

#5 tailgatewagon

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Posted 23 August 2005 - 10:56 PM

well i have yet to use any kind of silicon on my 8 water pump replacements ive always used oem subaru gaskets and cleened the serfaces good. one thing is they there can be no water or moisture near the gasket when you put it on. once its torxed it will work fine but untill its torqed it will be distroyed by water or moisture..... anyway good luck and let us know how it transpires.
(oh yea thats 8 differnt cars not the same one..)

#6 sregor13

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Posted 23 August 2005 - 11:06 PM

True it might work without. The Haynes Manual and Mitchell-on-Demand call for Blue RTV. Probably overkill, but I will say that mine leaked at first without the RTV. I think it might be due to threads on the bolts being a little worn and not being able to ( or being afraid to torque to factory spec) I am glad to know that no sealant is needed. I do recommend it anyways but dont use to much becasue I think I read a thread where the RTV was on so thick it slowed the movement of the Water Pump Fan itself along with Water Flow. If mothing else the RTV makes it easier to put on the Gasket without getting it cocked and whatnot. Thanks

#7 stephenw22

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Posted 23 August 2005 - 11:17 PM

RTV is really greasy when it's first applied. If you torque the gasket down tight right away, the gasket will squeeze out and it will leak, 100% guaranteed.

If you apply the RTV and let it set before tightening, then it will work very well. In the past, what I've done is to apply silicone to both sides of the gasket before installing it. Then, I only tighten the bolts finger-tight, or enough for the water pump to make very light contact with the gasket. Then, the next day, I'll tighten it the rest of the way.

These days though, I only use the gasket, no RTV at all. I don't even worry if it gets a little wet during installation. They seem to hold just fine on their own.

For me, what's most important is having a perfectly clean gasket surface. I'll scrape it with a flexible putty knife, then with a razor blade, and then buff the surface with a scotchbrite pad.

#8 Ryker

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Posted 29 August 2005 - 02:56 PM

Well I don't know how to feel -- lucky or foolish. I finally took the time this afternoon to tear in... and guess what? Having presumed all along that the gasket had gone, taking off the alternator I was bowled-over to find that I had forgotten to bolt down the water pipe (that leads to the radiator outlet)... :o Popped her back in, bolted her down, and added water -- leak plugged! :rolleyes:

I appreciate all of the responses, though! It's information sure to prove useful.

In conclusion:
:banana:

#9 MorganM

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Posted 29 August 2005 - 02:59 PM

Replaced my water pump this winter. Used a razor blade to CAREFULLY remove old gasket material. This was the hardest part. Some places it LOOKED like it was all gone but it wasnt. Brake cleaner assisted in softening up the old material left on the gasket mating surface.

Then used gasket and Blue RTV sealant. It's held up great now ever since installation. Few thousand miles on it since then. Oh another tricky part. THere is one spot where the cooalnt dribbles down along the block. Well RTV doesnt stick where coolant has made the surface wet! I could see that easily becoming a leak in teh future. Took the time to dry out the whole orface where coolant was dribbeling out of, then applied the RTV, and applied the gasket with pump.




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