1975 coupe

I'm in Florida - so it's not cold here (should it matter)

350 Z28 Camaro Motor......

Sooooo, I wanted to tweak the quadrajet a bit today and backed the rear end out of the garage, removed air filter, started car until the choke was no longer engaged.

Did some minor changes to the carb and shut the motor off.

I dropped my screwdriver on the floor and when I went to pick it up I noticed coolent dripping to the floor. With the car lowered, I really couldn't tell where it was coming from..

Jacked the front up (tires about 2" off the ground), put jack stands on the thing, but the drip, by now, had stopped.

Soooo, started the motor up again - let it run a bit - shut it off and the drip started up.

No notice of drip with motor running, just when turned off.

I went under the car, and the drip seemed to be "weeping" out of the bottom of the water pump (the part where the lower hose connects), but not near the hose, it's like on the very bottom of the pump...

Nothing noticeable above that point.... while dripping it almost seemed like a tiny pin hole in the casing of the pump.

I wiped it down best I could because I wanted to catch it starting to weep next time around.

I wanted to see how low the coolant was in the radiator, so I slowly released pressure and took a look. The radiator was to the brim.

Put the cap back on (tight), started the car - let it run... shut if off .... no leak.

I repeated this two more times and I swear the leak stopped.

Now then, WTF is going on???

Thoughts, suggestions, and bullets for my shotgun greatly appreciated!

Thanks,

Len

 

Those are the best kinds of leaks, the ones that leave nagging doubts in your head. You could have a casting weep that was plugged by some particulate in the coolant (those pills you used to put in the radiator for example). You could have a small leak that expansion of the metal stops (hence the hotter it got the leak stopped). My guess would be that it is coming out of the bearing and is hidden by the pulley.

Good luck!

 

I think you already know what needs to be done. Search some vendors for pump prices. Make sure its for the correct year Vette. You can't slap any ol' SBC pump on there, they are different. I believe the shafts come in two sizes also. I believe there are three SBC waterpumps: short, long & Vette.

AutoZone has some Permatex RTV, small tube, specific for the waterpump gaskets and /or thermostat housing gaskets. It holds up well to glycol.

Not too bad a job, you already have the front up in the air. Drain system. Label your belts with masking tape / felt pen which order they came off and where they go:
A/C, ALT, P.S. Air Pump, etc. Box-end wrench on the fan nuts, remove lower hose, one heater hose. Make sure you put a thread sealer back on the pump bolts. I believe they go into the water jacket.

 

Good info, the Corvette is a short pump with a 3/4 inch shaft (typical is 5/8).

 

So question is match the water pump to the "corvette" or to the "camaro" motor that is in the car????

 

I agree, sounds like your pump seals going bad. There is a "weep" hole on the bottom side of the casting where the shaft goes through. My bet is it's leaking just enough to run down the pump to the location you indicated then a drip forms.
My bet is if you take a rag a run it under the pump shaft housing it will be wet.

 

Depends on your engine driven fan and belt pulley. Measure the shaft diameter and go from there.

 

I'm not touching that question. I could get it wrong. Only you know whats on there (pullies-brackets-W.P.)
Its your call.

 

If the pump has numbers, write them down. Otherwise, pull the pump and take it to the parts house. You can also kit a water pump. Not that hard to do.
Stump

 

Pressure testing the cooling system will leave you with absolutely no doubt where the leak is coming from - that is what I would do first.