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Coolant leak on 74 454

74 454

Active member
Joined
Apr 25, 2007
Messages
31
Location
Michigan
Corvette
1974 Brown Coupe 454 4-speed
I have a small coolant leak that ONLY leaks AFTER I shut the engine off! At least as far as I can tell. I shut the engine off hot, and after about 2 to 4 minutes, it starts to drip about one drop every 30 to 60 seconds on the passenger side bottom of the radiator about where the tub and core come together. But it's not clear that it's coming from this connection. It can just as easily be running from somewhere else. But it just seems strange it only leaks after the engine is off. And it stops after only leaking about a 2 inch round puddle. I had it out a couple of weeks ago on an 87 degree day in stop and go cruise traffic for 2 hours. Got very hot everywhere. Temperature gauge never got above 200 degrees! No signs of any leaks! Should I check the cap? The over flow bottle and hose? I even put stop leak in also a couple of months ago. The cap, radiator, bottle and hose are all original equipment from 1974.
 

72VETTE454

Well-known member
Joined
May 30, 2004
Messages
82
Location
MI
Corvette
1972 Convertible LS5 4spd
My 72 big block does that on occasion. On mine, it's coming from the overflow on the expansion tank. See where the hose ends up coming from your expansion tank, that may be where it is leaking.
 

zachh

Well-known member
Joined
Aug 1, 2005
Messages
221
Location
virginia beach, va
Corvette
1979 black 'n' silver L82 1978 Trans Am Y88
theres a little drain screw at the bottom of the radiator. Check that its tight. When the coolant gets hot, it expands, causing a pressure of 15 to 19 psi. When the engine runs, coolant is moiving, when the car isnt running, the coolant is just sitting there.
good luck
zachh
 

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