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Old 06-29-2019, 01:10 AM
Goatracer1 Goatracer1 is offline
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Default Water pump gasket leak.

1964 421 water pump to timing cover gasket leak. The water pump is fairly new (from Ames) and I don't see anything wrong with it or timing cover. I have replaced the gasket that came with it twice with new gaskets for seepage.. It seeps coolant out around the gasket. The first 2 gaskets were coated with Permatex High Tack spray. The last with Permatex Forma Gasket #2. It can leak at any point around the pump. To stop the leaking I've added a "stop leak" to the coolant. It seems to have worked at least for now. Is it possible the gaskets are just too old and aren't sealing. They can't be producing many of the gaskets now.

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Old 06-29-2019, 11:02 AM
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OCMDGTO OCMDGTO is offline
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Had a very small leak recently myself. Turns out it was mostly coming out of a bolt hole which only needed some Pematex on the bolt. I also tightened up all the other bolts after a drive when it got cool enough. Much easier than taking the whole pump off. No more leak!

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Old 06-29-2019, 11:03 AM
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Had a very small leak recently myself. Turns out it was mostly coming out of a bolt hole which only needed some Pematex on the bolt. I also tightened up all the other bolts after a drive when it got cool enough but still warm. Much easier than taking the whole pump off. No more leak!

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69 GTO Liberty Blue/dark blue 467, 850 Holley, T2, Edelbrock Dport 310cfm w Ram Air manifolds, HFT 245/251D .561/.594L, T400, 9" w 3.50s 3905lbs 11.59@ 114, 1.57/ 60'
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Old 06-29-2019, 11:15 PM
Goatracer1 Goatracer1 is offline
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As I stated I've had 3 different gaskets with no fix. The leak is never in the same place. Always used sealer too.

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Old 06-30-2019, 12:07 AM
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indymanjoe indymanjoe is offline
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Sounds like a porosity issue. Is the timing cover rotted out?

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Old 06-30-2019, 04:46 AM
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Assuming the timing cover is not porous .... if you have it back apart again ... I'd lap the sealing surface of the timing cover and the water pump. They have to be flat for the gasket to work ... and sometimes they are not very flat.

Within reason I lap every single surface I can. It's easy if you have a large enough FLAT surface and some lapping compound ... almost fun in fact, kind of a Zen thing

Although ... the water pump can be problematic with the impeller installed as it sticks out past the gasket surface. Usually the pumps are pretty flat ... but the timing cover can do all kinds of warping, corroding and in general misbehaving in 40-50 years.

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Old 07-01-2019, 06:47 AM
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Quote:
Originally Posted by Goatracer1 View Post
As I stated I've had 3 different gaskets with no fix. The leak is never in the same place. Always used sealer too.

Go get yourself a tube of gasket sealer called, The Right Stuff by Permatex.
Coat both sides of the gasket and install. Put some latex gloves on, easier to do. You can put a bit on the bolts if they go into the water jacket .

As others have pointed out, check timing cover with a straight edge.

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Old 07-03-2019, 12:26 AM
Goatracer1 Goatracer1 is offline
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I'll try that other sealer. The leak is coming out of the gasket itself. When I take the gasket off(in one piece) it feels soggy and is very flexible. It's like the gasket isn't doing anything. The gaskets are Felpro if it matters. When I install the gasket it is fairly stiff.

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Old 07-03-2019, 01:00 AM
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Do you have original bolts in it? Just thinking maybe a bolt or two is bottoming out.

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Old 07-03-2019, 10:38 AM
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Quote:
Originally Posted by Goatracer1 View Post
I'll try that other sealer. The leak is coming out of the gasket itself. When I take the gasket off(in one piece) it feels soggy and is very flexible. It's like the gasket isn't doing anything. The gaskets are Felpro if it matters. When I install the gasket it is fairly stiff.
I would make sure you use the blue felpro gaskets. I think some are brown.

https://www.summitracing.com/parts/f...3/make/pontiac

Also like has been pointed out. Make sure bolts are not bottoming out.

Almost sounds like timing cover is loose.

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Old 07-11-2019, 08:49 PM
Goatracer1 Goatracer1 is offline
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Have original bolts and gaskets were brown. Will look for Blue gasket.

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Old 07-12-2019, 01:34 AM
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Mister Pontiac Mister Pontiac is offline
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I've had the best luck using nothing but good old fashioned blue permatex silicone (or ultra blue) and the blue Fel-Pro gaskets. The key to a leak free install I've found is two fold...

First, be sure to chase all of the threads on the bolts and tap the holes in the timing cover completely. Be 100% sure the bolts all thread in by hand, all the way down, and (as previously mentioned) that none bottom out prematurely.

Second, coat both sides of the gaskets completely (but not too liberally), and gently run the bolts down finger tight until the silicone just begins to ooze out. Stop there. Wait 24 hours for the silicone to cure, then torque the bolts (only 10-15 ft lbs if I remember correctly. It's a very light torque).

Using this technique, I've had perfect success with both the 8 bolt and 11 bolt design pumps and covers.

Hope that helps.

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