Have just noticed a leak apparently from the water pump after a complete engine rebuild including the pump. From underneath, the dripping looks as if it's running down from behind the harmonic balancer. The confusing thing to me is that it doesn't leak until the engine warms up or the thermostat opens. Why wouldn't it leak all of the time the shaft is turning? It's not coming from the pump side mount gaskets so does this mean from the rear plate gasket or what?
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Re: 67 BB water pump leak
It could also be leaking from the upper bypass hose (slight mis-match between hose, nipple and clamp) then weeping down the back side of the pump's housing... -
Re: 67 BB water pump leak
My 66 BB was leaking the same way and only after it heated up. I found that after it warmed up the pressure built up in the cooling system and my leak was from the back plate on the waterpump. The bolts there were not tightened properly. I tightened them with the pump still on the car, but it isnt easy. I had to grind an open-end wrench thinner to fit in between the pump and the front of the engine. Got er done and no more leak.
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Re: 67 BB water pump leak
Had a leak in my 67 BB waterpump after changing antifreeze to the red/orange stuff. It would leak a few drops after warming and pressure build and then engine shutoff for a few minutes.
Put the good old green antifreeze back in and the leak went away....Comment
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Re: 67 BB water pump leak
Larry, thanks for that but unfortunately my back plate has screws instead of bolts so I'll be taking the pump off tomorrow.
And Stephen, I believe your car and mine were off the line 1 day apart. I have serial 5656.Comment
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Re: 67 BB water pump leak
Tom-----
Just as others have described, I am very confident that your leak is from the backing plate and begins when the pressure in the system builds up to a certain point. If you are using the "flat" style backing plate, that could be a big part of your problem. These are the most difficult of all backing plates to seal. You can try just tightening the screws and see if that "does the trick". If not and if you want to stick with that style backing plate for originality reasons, here's what I recommend you do:
1) Remove the backing plate; make sure it's completely flat and not distorted or bent in any way;
2) Remove all traces of the gasket and any sealer that might have been used from both the backing plate and the pump casting;
3) Apply Permatex #2 sealer to the complete gasket sealing area of the plate and pump;
4) Install a new gasket
5) Tighten the screws to 90 inch/lbs in a DIAGONAL pattern.
I made up a test rig once-upon-a-time to test waterpump sealing at various system pressures. I found that NO backing plate would seal at pressures exceeding 18-20 PSI. I had a very hard time getting the "flat" type plates to seal even at 10 PSI, which is below normal system operating pressure.In Appreciation of John HinckleyComment
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Re: 67 BB water pump leak
One of the few remaining water pump rebuilders here in Denver agrees with you Joe (flat rear plates are a PITA in terms of gasket sealing integrity)! When he does a pump rebuild that requires factory concours authenticity, he 'cheats' by taking the cleaned up flat rear plate, mounting a lower edge in a vise and ever so SLIGHTLY bending it to obtain a modest C-shape to the plate's cross section.
Then, when the mounting bolts/screws are installed, the rear plate will have some residual tension to make 'er want to stay compressed against the gasket....Comment
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Re: 67 BB water pump leak
The back plate on my pump was not the flat style but had the turned up or flanged edge. The mounting screws were loose when I removed from the engine, thus causing the leak. I heated the entire pump in a pan of water on the stove to 180 degrees using a meat thermometer to allow the metal/steel to expand if it was going to. After removal, I was able to tighten all of the screws about a half turn more than when cold. I've reinstalled on the car and so far no leaks.Comment
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