Topic: 1937-48 water pump to block small leak


thewmon    -- 01-17-2020 @ 2:20 PM
  Hello,
Seeking advice.. last May I replaced both 37-48 style pumps and used the red tacky Permatex 80062 high tack gasket sealant on both sides of the gaskets that came with the water pumps. And used Permatex 80632 thread sealant on the bolts. My left water pump has been bone dry 500+ highway speed miles, but the right one is experiencing small leaks from what I can tell (running continuous video over night) seeping though the top of the gasket. If I take it out for say a 20 mile highway speed cruise, the top tank of the radiator will have ~1in less of antifreeze.

I've retorqued the bolts. Any advice in trying something fairly "easy" before I take it all apart (which won't be easy with tacky sealer), clean, and try again?
thanks!
Matthew


kubes40    -- 01-17-2020 @ 2:50 PM
  If the surfaces were true and clean on both the pump and block, I'd suggest a new gasket and Permatex silicone sealer. My guess is there is some kind of small imperfection on the block and / or the pump. If it's small (imperfection) the silicone sealer will work its magic. The hi-tack stuff won't fill tiny voids.


Mike "Kube" Kubarth


TomO    -- 01-18-2020 @ 8:27 AM
  I would remove the pumps and examine the block and pump surfaces for imperfections. Use a scr*per to clean the gasket surfaces, a 5 in one tool works great to clean off the gasket surface. CRC makes a gasket remover that will soften the adhesive to allow easier removal of the gasket cement. Be careful as it may also damage the paint on the engine. You must wear protective gloves while using it or disposing of the remnants. Here is the Safety sheet on it;

http://docs.crcindustries.com/msds/1003638E.pdf

I have not had to use it on gaskets caoted wi6h Hi-Tack.

If there is a crack in the block, have it stitched, if there is a gouge out of the gasket surface, try the silicone goop. If the problem is in the pump surface, get another pump.

The gasket should seal any small imperfections in the sealing surfaces.

Tom


JayChicago    -- 01-18-2020 @ 9:44 AM
  This brings up a question in my mind: What do you all think about using a chemical sealant in the coolant, like Barr's Stop-Leak?

I have used it with success on small weeping leaks on modern cars, with no ill effects to the cooling system that I was aware of. I read that some new cars got it on the assembly line. But these are pressurized cooling systems, and it may need that pressure to find/fill the leak and then coagulate when exposed to air.

And then the bigger question: could it do some harm to our water pumps, etc?


TomO    -- 01-19-2020 @ 8:54 AM
  Barr's has been used by many flathead owners without causing problems. I prefer to fix the problem by doing a quality repair.

Tom


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