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checked the coolant before starting the car in Breckenridge, CO. About 3.5" below filler neck. Checked it hot back here in Lincoln, NE and it was a little over a gallon low. No noticeable leaks (heater core shut off, all connections dry) and nothing in the catch can. No milkshake on the dipstick, no smoke in the exhaust, not running particularly rough.

Where'd that gallon of coolant go? Bubble in the block somewhere? Air in the system that compressed with the elevation change? :WTF


Additional details:
Stayed right at 180* the whole way home on the interstate. Pulled into Lincoln and put 4 gal. of 87 octane in the tank (no premium at that station) to get the next couple miles to the next station with 92 octane. Leaving the second station the temp gauge is brushing the red mark. No indication of knock due to low octane. Mom and dad were driving at the time, and they should know what to listen for.
 

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checked the coolant before starting the car in Breckenridge, CO. About 3.5" below filler neck. Checked it hot back here in Lincoln, NE and it was a little over a gallon low. No noticeable leaks (heater core shut off, all connections dry) and nothing in the catch can. No milkshake on the dipstick, no smoke in the exhaust, not running particularly rough.

Where'd that gallon of coolant go? Bubble in the block somewhere? Air in the system that compressed with the elevation change? :WTF


Additional details:
Stayed right at 180* the whole way home on the interstate. Pulled into Lincoln and put 4 gal. of 87 octane in the tank (no premium at that station) to get the next couple miles to the next station with 92 octane. Leaving the second station the temp gauge is brushing the red mark. No indication of knock due to low octane. Mom and dad were driving at the time, and they should know what to listen for.
You have a small leak somewhere! Apparently it is only leaking when under pressure. I would pressurize the cooling system and check for leaks. It could be a leaky hose, loose hose clamp, leaky thermostat gasket (top of intake manifold) worn out radiator cap (weak spring or gasket shot), leaky water pump, heater hose, heater core or radiator (did I forget anything?) Those are the obvious ones.
I hope that helps!
PS - the radiator cap is one of the easiest and cheapest to repair and frequently overlooked.

What qualifies me to give this advice?
ABSOLUTELY NOTHING.
Take it at your own risk!
 

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You have a small leak somewhere! Apparently it is only leaking when under pressure. I would pressurize the cooling system and check for leaks. It could be a leaky hose, loose hose clamp, leaky thermostat gasket (top of intake manifold) worn out radiator cap (weak spring or gasket shot), leaky water pump, heater hose, heater core or radiator (did I forget anything?) Those are the obvious ones.
I hope that helps!
PS - the radiator cap is one of the easiest and cheapest to repair and frequently overlooked.

What qualifies me to give this advice?
ABSOLUTELY NOTHING.
Take it at your own risk!
:agree: It went somewhere. IF you have a pinhole in the heater core, and ran the a/c, it might have mixed with the condensate draining, and appeared normal. A system in good order with a good cap should suffer no coolant loss.
 

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Re tourque the intake manifold? Chebbys are noted for swallowing small amounts of coolant from the intake water passages to the intake runners :crazy: but true... It happened to me twice... Once on an 84 SBC and once on a 88 BBC.

FWIW :thumbsup:
 

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IF It is really a gal low you better take it to someone that under stands engines..:thud:
 

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a gallon is a lot of coolant to lose, if it was me I would beg, borrow or steal the kit to pressurize your cooling system so I would know for sure....try Autozone they loan tools and might have what you need....or a "friendly" radiator shop.
redvetracr
 

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Discussion Starter #8
the whole system is new... alum rad, new hoses, new pump. Just retightened all the clamps before heading out. The heater core started leaking a little while before we left, and on the first leg of the trip it finally let go and we lost some coolant inside and down the firewall. The supply line to the core already had the valve shut, so we got some extra heater hose and a bolt to cap off the return line and the oulet from the engine.

It really is running just fine right now. I'll check around the heater core again for evidence of coolant escaping there. Maybe the valve in the line isn't closing fully. :huh:
 

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That's a lot of coolant to loose, did you check the dipstick on your engine AND your trans?
 

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Discussion Starter #10

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Not uncommon for those inline heater shut-off valves to seep a bit. Sure fire cure is to bypass the heater core.


:cheers:
 

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I'd suspect the heater. It could be leaking through the valve, into the core, down the interior firewall/footwell under the carpet, and out the drainplug in the floorpan.
Pull back the carpet on the passenger side and check the pad & floor for moisture.
Did your parents notice any sweet smell while driving? Or perhaps some fogging of the windshield? That would be leaking heater core for sure.
Try removing the heater lines at the engine and install a piece of hose between the engine fittings so the heater is completely out of the coolant loop. If the core is seeping, it is within moments of failure and major flooding, so you need to disconnect it now anyway.
(And yes, I am very qualified to make the above statements! :laughing: )
(Edit: Guess you already said some of that, huh?)

Another thought--verify the hose from rad cap to overflow/expansion tank is clear and has no holes or splits, thus making a total loss of expanding coolant from the radiator.

John
 

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Guess I gotta be the cheeeeeepest SOB on this forum....all I do is pull a heater hose, like from the shut off valve, use another piece of hose, allready sweated some 1/2 copper pipe/tee into a a/c fitting, use the a/c hose set, pressureise it with compressed air through the canister line....like I use for pressure testing the a/c system for 4-6 hours before evac/charge.....

and let the air into the cooling hoses up high, and pressure to the point of popping the rad cap off a bit....sit and watch/wait till hell freezes over if necessary.....

I"m a lazy bastard too, kick back and have a beer....

:crazy: :rolling: :D :cheers:
 
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