The Case of the Missing Coolant - or - Gasket Death?

All,

First time post here. A little about my situation (CO locations used for reference, as applicable):

While driving uphill on the I-70 corridor and nearing the Eisenhower Tunnel, heat gauge suddenly spikes and start to live on High. Cools down slightly while leveled out inside the tunnel, but still manages to stay pretty high even coasting down the hill on the other side of the pass. We pull over, see that the coolant is almost empty and it's been spraying all over. We get a last minute assist from a family shop in Silverthorne (about quittin' time). No visible pooling or leaking. He diagnoses the issue as a broken thermostat, swaps it out, and we are back on the road. Grab a jug of coolant just in case, and drive another 100+ miles with stable temps. Crisis averted....or is it?

Next day, driving the truck up onto Grand Mesa on the western slope, the temps start rising all over again. No time to add new coolant before we are a steam cloud on the side of the road. Give the truck time to cool a bit, see we are almost out of coolant in the reservoir. Again, no visible pooling or leaking. Add more coolant, drive back down the hill, again the coolant is low. Park the car, add more coolant, run the engine, rev it hard, and watch Uncle Taco SUCK down coolant.

Drive it to a shop in Grand Junction, they find a faulty fan. Block test reveals no exhaust in the coolant. I'm thinking this is a bad/blown gasket, but I'm presenting this to y'all with high hopes you've seen otherwise.

Ideas?

 

A "bad fan" does not drain coolant from a closed system. You have a leak somewhere. Time for a pressure test.

 

Have you pulled the dipstick to see what the oil levels is like? If your coolant is clear and there’s no water in the oil pan, chances are the gaskets okay.

Do a series of leak down tests and a cooling system pressure test. Those should help narrow it down. It could be a hose or cracked fitting that gets worse as the system heats up.

 

Thanks. I should clarify - latter mechanic said bad fan initially, but when he reviewed the coolant levels again and saw they had depleted just in the drive to his shop, he also agreed that it may be a gasket issue. I mention both the failed fan and the missing coolant as there may be multiple points of failure in the cooling system (after the initial failed thermostat). He did note sufficient pressure in the system.