GM water pump

[Greg Hermann]

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