Cooling System Prep, Keeping Your Engine Cool This Summer

Your engine makes a lot of heat, and in summer it has the least help getting rid of it. Add Colorado altitude, a long uphill grade, a loaded roof rack, and an afternoon in the nineties, and the cooling system is doing the hardest work of the year. A boil-over on the way to the mountains is almost always preventable, and prevention starts with a spring check.

What the cooling system actually does

Coolant circulates through the engine, picks up heat, and carries it to the radiator, where airflow pulls that heat out and dumps it into the air. A water pump keeps it moving, a thermostat regulates the temperature, and a pressurized cap raises the boiling point so the coolant can run hot without flashing to steam. Every one of those parts has to work, because the system has no margin to spare on a hot climb.

Where summer cooling trouble starts

• Old or low coolant. Coolant breaks down over time and loses its corrosion protection and its boiling resistance. Low coolant means air pockets and hot spots.
• Tired hoses. Heat cycles make hoses go soft or brittle. A hose that bursts on the highway dumps your coolant in seconds.
• A blocked radiator. Bugs, cottonwood fluff, and road grime clog the fins so air cannot pass through. Common in Boulder once the cottonwoods fly.
• A weak water pump or stuck thermostat. Either one can let temperatures climb even when everything else looks fine.

Why altitude raises the stakes

A long climb up Boulder Canyon or over a high pass asks the engine to make power for an extended time, which means making heat for an extended time. The thinner mountain air carries away heat a little less efficiently, so a cooling system that is even slightly compromised runs out of margin faster here than almost anywhere else. The temperature gauge creeping up on a grade is your warning, and it is one you want to never see.

What a cooling system check includes

We pressure-test the system to find leaks before they strand you, check the coolant condition and strength, inspect the hoses and clamps, look the radiator over for blockage and corrosion, and verify the water pump and thermostat are doing their jobs. If the coolant is past its service life, a flush and fresh fill restores both the boiling protection and the corrosion protection. It is a modest service that prevents one of the most common and most avoidable summer breakdowns.

Keep your engine cool and it will carry you up every pass and back without drama. Get the system checked this spring and drive the summer with the gauge sitting right where it should.