GM water pump

[Martin Powlette]

Thanks Greg at least that is the theory I am working on now.  The bleeder tap is on
the top of the pump its a 3/8 drive plug.  I looked at one of  the ol pumps and the
ceramic seal looked burnt the mating seal has a copper surface and it was all worn
out.  The copper like seal has a lip on the inner dia. and that looked worn but that
was the pump with the worn out hub.  Since then I have replaced the hub and fan
clutch, the fan looks ok.  I will open up the pump that is on now, it leaked after a
1 1/2 days.  I ordered a new pump and intake gaskets just in case.  This time I am
going to use a really good coolant/antifreeze that will help lub the pump seals,
bleed the system properly and check that all coolant passages in the intake are
clear.  I'll keep you up to speed.

Martin


Greg Hermann wrote:

> Hi--
>
> Don't know this engine, but on most, there is also a small air bleed hole
> somewhere near the thremostat (usually 1/16 to 3/32 diameter) which lets
> air bubble past the stat during initial filling. This is easily plugged
> with "stuff". If it has become plugged, you might be getting a really big
> air pocket when filling that does not go away until the stat opens on first
> warm up. Could it be that this is causing the seal to run dry long enough
> to tear it up??--Also, bent or otherwise jammed stat??
>
> Regards, Greg
>
> >> Carl this thing is begining to make more sense and with your mail it
> >>jumped two
> >> clicks.  I will check your suggestions as soon as I get the new intake
> >>gaskets,
> >> just in case.
> >
> >Lets add one other thing, what if the engine starts and there is an air
> >pocket in
> >the pump a dry-start to be precise.  Aren't the seals one ceramic and the other
> >copper like with a lip seal on the shaft as part of the second ring.  We used
> >coolant(rust inhibitor,bit of green stuff) instead of ethelyne-glycol
> >antifreeze
> >so the lubrication quality is not the best. But on the other side of the
> >aguement,
> >if it is the coolant I have got another vehicle same engine running on
> >that same
> >coolant with an intake job I did myself.  BTW at what point do you put the 3/8
> >drive plug on the pump??? after refill to bleed out the air or before
> >installing
> >the pump to trap the air??Just for thoughts, give me yours Carl.
> >
> >Martin
> >
> >
> >>
> >>
> >>  Hi Martin,
> >>       It seems I remember chev's having a bypass underneath the thermostat to
> >> bypass water back to the water pump while the thermostat is closed and
> >>as this
> >> passage gets old and crusty with rust, block pressure rises with rpm and
> >> pushes past the seal in the water pump,,,,and yes you are correct there is a
> >> plate in the intake gasket that is supposed to be in the rear of the
> >> engine,,,,,an easy way to check for this is to remove the thermostat housing
> >> and unbend a coat hanger(DIY lol) through the passage to see if the plate is
> >> in the front by accident....p.s. I have seen many marine engines at over
> >>30lbs
> >> block pressure and not push past the water pump seal....but over 50 it is
> >> inevitable....keep in mind block pressure does not necessarily mean radiator
> >> pressure.....and if checking block pressure you have to check both sides of
> >> the block as it does not equalize until it joins at the thermostat....hth's
> >> -Carl Summers