L48 Cooling
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Joined: Jul 2005
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L48 Cooling
Can anyone tell me why when I open the radiator cap on my 78 L48 PC it is not full to the top (actually empty to the overflow line) but my 78 L48 SA is full to the top when opened? And the PC has leaked out of the cap. I replaced it but it still seems to leak just slightly but the overflow is fine. And the PC has a 16lb. cap when the SA has a 15lb. cap. If I want to keep the PC cooler in traffic should I switch to the 15lb?
Melting Slicks
Joined: Mar 2009
Posts: 3,126
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Is there a hole or crack in the hose from the radiator to overflow tank? A leak here would prevent the rad. from refilling when the coolant cooled off. One pound of cap pressure should not make much difference. Cap needs to have a valve in the center that allows coolant to return from tank. mds...
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
If the L-48 engine does not have an overflow tank, you have to leave expansion room in the radiator for the water when it heats up. The mark on the upper tank is the FILL level mark on that kind of system. Your '78 car has an overflow tank. With that kind of system, the radiator is completely filled and the o-flow tank is filled to it's FILL line. The water expansion is then taken up by the o-flow tank, rather than the radiator.
