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Discussion Starter · #1 ·
Hello I have replaced the water pump on my 1979 GMC Calberrro because it was leaking at the water pump gasket on the passenger side. So I replaced the waterpump and gaskets.Two days later it started to leak again so I exchanged the water pump at Autozone and replaced the thermostat with 180* and the pressure cap 16ilbs (they said that was the proper rating). and today when i was coming back from lunch (I drove and had parked it for 20-30 mins)it was leaking from behind the water pump again but it wasnt leaking before i went inside to lunch. And when i opened the radiator the leak stopped. So my Question is the pressure cap on my Car falty or too high? I dont want to change the water pump again until im sure of what the problem is.
 

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A couple of other ideas.

Is there a freeze(soft) plug there that could be leaking, or maybe a head gasket?

Or the front of the intake?

Get a pressure tester and pump it up and see for sure.

Also I have always used ultra-whatevercolor rtv and never had problems but when I put the new pump on my Elky I pressure tested it first and both those and the t-stat gasket leaked. I redid the gaskets with spray-on copper coat and havent had a single problem.
 

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Discussion Starter · #4 ·
Im pretty sure its the water pump because i can clearly see coming from right below the water pump and block. I have been checking it out.
Does anyone know the torque specs on the water pump? Or maybe some hight quality gaskets other than the paper one that come with the water pump?
:nanawrench:
 

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Its a basic 3/8 bolt should be 20-25 lb/ft

Also put some sealer on the bolt threads.
 

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Its a basic 3/8 bolt should be 20-25 lb/ft

Also put some sealer on the bolt threads.
X2 on the sealer on the bolts. The two bottom bolts go directly into the water jacket.
 

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it could be the comming from the weep hole or the back cover on the pump,,
it might be running down and dripping off under the pump mount/block,,
or the mounting surface may be damaged on the pump..
if its a rebuilt pump,,that may be it..

did you scrape off the old gasket/clean the block?? tighten the bolts down evenly??
i never had one leak at the block,with or without rtv/ gasket..:texas:
the pressure cap is fine at 16#
 

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A while back I changed the waterpump on a suburban and got two bad sets of gaskets,the darn things fell apart before it got out of the driveway.What I ended up doing was I took clear laquer (spraycan) paint and saturated the gaskets and let them dry and that solved my problem with that set of paper gaskets,to this day no problems with it.
 

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Discussion Starter · #11 ·
Haha yea thanks for the imput everyone. What i ended up doing is buying some felpro gaskets and some blue rtv. Put it back together using a torque wrench at 25 ftlbs and tightened the bolts in a cross pattern. Let the RTV set overnight and filled up the cooling system and (knock on wood) no more leaks
:nanawrench:
 
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