What the heck am I doing wrong? I changed the water pump 4 1/2 weeks ago in my '97 Chevy 5.7 2wd Silverado. the factory one started wepping, so it was time after 153,000 miles. One week ago today, I was clipping down the highway when it blew the gasket on the passenger side out. (see the thread in the lounge under the heading Bullheimer Luck) I lost all coolant, and dumped in 2 20 oz. bottles of water in so I could track the leak. I finally got to work on it Sunday morning, got the leak stopped by installing new gaskets with a small film of RTV to hold the gaskets to the pump to ease the mounting. I didn't drive the truck more than 15 miles, and now it's sitting in my driveway leaking antifreeze into the drainpan...again. So, what is the deal? Bad new pump that is just not sealing? Bad bearing in the pump? I'm getting really tired of buying antifreeze.

The antifreeze that I am using now is the Prestone stuff that is good for all makes and models.

Thanks in advance for the advice, Chet.

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First thing comes to my mind is...did you scrape the mounting area good before reinstalling? Even a little bit of crud will allow the coolant to work its way under the gaskets seal then its downhill from there.

no clue on this one, but this just a random idea, is a passage plugged with something and pressure build up and coolant busts its way loose through the weakest link "the gasket"?

It could be leaking out the shaft if its worn enough.....

Mounting surfaces flat? not warped....

Did you tighten the w.p. bolts good enough?

Did u get both sides of the gasket with rtv or just one side?
I usually put some one the block, the water pump, and both sides of the gasket. Just a thin amount rubbed on by finger, dont want too much ya know...

Thats about all I can think of at the moment.

g'luck to ya.

Maybe some "high tac" gasket cement will do the trick.

Yup, you need to see metal on both sides. i stopped using a gasket for the SBC water pump {since the advent of sepentine belts} and stopped using a gasket for the thermostat housing. Permatex Ultra-Blue is what you need.

Doc here,

And after you see bare metal, Scruff it with some 60 grit paper until you see scratches, on BOTH metal surfaces..the Sealer will have something to "GRAB" on to this way..

Doc

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I had a similar problem on my daughters 4.3 S-trk. On her way home from work one morning. She had a water pump fail and limped the truck home at 3:00 am. TOO LATE! cooked the old 4.3.

I had a new 4.3 short block at the shop so it went in the truck. Along with a rebuilt water pump from a major auto parts retailer. My real parts store is closed on Sundays. Fired the truck up and it leaked at the pump to block gasket. Tightened it up more, still leaked. Took the pump out and installed two gaskets on each side. Leak stopped, or so I thought. 20 minutes later my daughter is calling me on the cell.. "The truck overheated and stopped". Damn,, that was a new motor!!

So I tow the truck back. The water pump is spewing coolant out the block/pump gaskets again. I take the pump out again!! Not a fun task on a 4.3 S-er. This time I laid the pump, gasket surface down, on a mill table. The the pump rocked back and forth.. I then took a straight edge and a couple of feeler guages and measured about .060" taper from flat on each mounting surface.

At close inspection (after removing all the cast iron paint) I could see that the rebuilder had resurfaced the mounting surfaces with a belt sander!!
not even close to flat. I was PISSED!

Next day I returned the pump, made it known that I would never step into one of their stores again. Bought another pump from my regular guys. Re-installed it and fired the engine. Fingers crossed. I was mad enuff to suit that Major parts retailer, if the new engine was hurt. Luckily it fired and ran with no problems and has served many miles since.

Sounds like the pump goes back to me. It makes no sense to me why else it would do that.

Thanks, Chet.

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Ive seen gaskets that were defective, had to throw away a whole box full of them. So it could be you did everything right and still it dont work. Ask for a set of Felpro gaskets or buy GM parts.

I used the Fel-Pro gaskets on it last time, instead of those el-cheapo gaskets that you get with the pump. At $1 each, I'll buy them from from my regular "real" parts store. When my dear wife comes home from work, AutoZone is going to hear it....

In a while, Chet.

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Alright. now I've got a new pump, it's all sealed down good, and I've got decent heat, but the temp gauge now climbs steadily when I'm on the gas (like when I pull up to speed at a highway on-ramp). It goes to 210, I let off and it goes right back to normal. It falls back at the same rate that it climbs. Am I just being paranoid over an air bubble in the system, or do I need to drain it again?? The level is normal for the overflow and the radiator is still full. Thanks again in advance.




In a while, Chet.

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