Car in sig loses 1 quart of coolant and no more in about 1 hour of driving...

here are the FACTS:

Ebay aluminum radiator
New cap
New thermostat
Coolant jug was filled on bench and held water over night with no leaks
No water in oil
No oil in water
No combustion in cooling system (chemical block test)
Coolant jug is empty all the time after the system loses the quart
NO external coolant leaks of any kind
No coolant burning in exhaust
Car does not overheat
Compression test = fine
Leakdown test= fine

Just to clarify, if I fill the system to the proper amount, and check it again after an hour of run time or 3000 miles the radiator will be exactly a quart low, and with empty coolant jug. It loses a quart and only a quart, no more, and no less, and is accurate pretty much to the drop! I am completely stumped, I have no effing clue what to do next. Any ideas? Thanks in advance!

 

you sure it isn't a leak? have you pressurized the system to check? i had a small tear in the loop hose on the IM, and it would only leak when the engine was running and the motor moved.

 

How is the rubber line running to the coolant jug?

 

My brother just fixed his "non-existant leak" - he found the leak after pressure testing the coolant system. He found a small coolant hose occationally dripping coolant onto the header's a-pipe - it was not visible unless you were under the car, and burned off before it could normally leave any evidence.

If you pressure test it and it looses a single PSI in a few minutes, there's a leak. If it's not a hose, it's rad's lip where the cap rubber seals. If that's warped enough, it will seem out into your overflow, push the extra out of it, and suck it back up after it cools.

 

Yes, pressure tested, didn't lose a single psi over the 20 mins I had it pressurized...

On its second brand new one LOL

I like this, any ideas on testing and repair?

 

...

 

zip tie the jug coolant lines

 

headgasket

 

which results of my testing indicate that?

 

Headlift while under boost. New head gasket and arp head studs would prob fix that.

But I ain't there to diagnos myself.

 

leaky heatercore?

 

motor is fully fully fully built, already has arp everything... also, it will lose that quart of coolant without ever going into boost... Even if head-lift was a possibility, that wouldn't explain why it loses exactly a quart and stops, it would eat it until there was nothing left...

 

Maybe try putting some UV dye into the coolant and using a blacklight to figure out where it's going?

 

thats my next step, just haven't gotten around to it yet...

 

ARP suggests re-torquing your head bolts after 1000 miles... DO IT...

 

Did you figure this out yet?