No heat from heater core when radiator cap goes on

I want my 57 chevy back! Now I have a 84 chevy c10 pickup and have heating issues. First installed new water pump, flushed out heater core (nice flow afterwards). Put in two differnt thermostates. Second
one high quality. Let run for 50 minutes to blead air out. Results no heat unless cap is off. Told head gasket could be bad. I dont see white smoke nor build up of water in oil. Totally lost on this problem any one with help on this issue, please contact me. I was told maybe I was sold a water pump with reverse fins that would be used for sepintine belts. When I accelarate the engine with the cap off, fluid gusses out of the radiator. Thanks for your assistance.
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Uh, no... That's a good indicator that something is really wrong!
The cooling system works by sucking water from the bottom of the radiator, circulating it through the engine and letting it flow back into the top of the radiator. If you are getting a gush of water at teh top, something is terribly wrong!
A blown head gasket won't always contaminate the oil. Check for combustion gases in the cooling system, do a pressure leak down test, and check to make sure you do have the correct pump on the engine.
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Sounds to me, like you just have air in the cooling system.........When filling it, have the engine running and circulating...That forces the air out.
See my truck group http://autos.groups.yahoo.com/group/OldTrucks /
Harry
PeterD wrote:

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