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Old May 5th, 2014, 02:44 AM
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GMCDAC GMCDAC is offline
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Location: Green Valley, east of Rapid City,SD
Truck: I have 4 GMCs, none with a V-6 - YET! Have had 2 in the family.
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Default Re: 1964 GMC 1000 Fleetside

Hi Aphaynes, Silver Seal radiator stop leak works well on small pin holes but I never liked Bars Leak very well. Some old timers claim a raw egg white in the radiator stops small leaks even!

It sounds like your cap is shot and that could be the source of the coolant in the fins. They are designed to release pressure at a pre-set psi. Yours may be stuck in the release position.

In my '55 GMC I just run a 7 lb. cap as I don't want to cause the 59 year old non-reproduced heater core to burst! Even hauling a load it is hard to get it over 180* so it seems sufficient. The V-6 experts here will recommend a cap pressure. On race cars we would run a 22-24 lb. cap. They may use higher pressure caps yet nowadays.

DAC
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Doug Crawford
Rapid City, SD

1970 GMC K5 Jimmy Mom drove 30 years
1972 GMC C2500 owned since 1979
1955 GMC 100 driver-project
2006 GMC Yukon Denali---wife's truck

Hope to have a '60 GMC Suburban again someday
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