5-point cooling system check: Radiator season!

We’re well into radiator season, but it’s never the wrong time to ensure your cooling system is in top condition. Boilovers and overheated engines are inconvenient or embarrassing at best, and crushingly expensive at worst. The air-and-oil cooled crowd might scoff with superiority, but a $5 radiator hose failure can result in $5000 worth of engine damage. As such, we put together a five-point cooling system checkup that could help prevent a meltdown during these sweltering days of August. Of course, be sure to start any cooling system work with the engine stone cold (preferably let sit overnight).

Radiator and Coolant

coolant test strip
Mike Bumbeck

Prop open the hood with an eye out for obvious leaks and a nose for coolants classic burnt syrup smell. Check the coolant level in the radiator and overflow tank (if so equipped) and give the coolant a look and sniff. Corrosive coolant can eat right through the radiator, so look for the telltale residue of coolant leaks around the radiator tanks and core. A ball-type tester can check coolant-to-water ratio by way of specific gravity, and coolant test strips can help prevent corrosion before it starts. Dip the test strip into the coolant, shake off the extra, and wait a few seconds. This coolant was on the edge of the pH limit, so out it went.

Hoses and Clamps

radiator hose
Mike Bumbeck

Replace any sticky, spongy, bloated, pinched, or otherwise dicey hoses. That one hose that looks like a snake that swallowed a gopher will fail at the worst possible time. Don’t forget to give the bypass and heater hoses a pinch. This water pump bypass hose looked OK from the outside but crumbled into dust like Christoper Lee in Dracula after Peter Cushing pulled the curtains and lit up the room with vampire-killing sunshine. Cinching up the hose clamps helps keep the coolant in the system and reveals any marginal or stripped-out bad actors. Screw type or jubilee clamps are notorious for eating into rubber if overtightened, so go easy on the twist.

bypass hose
Mike Bumbeck

Thermostat Test

thermostat burner
Mike Bumbeck

The thermostat is a temperature-controlled valve between the engine and radiator. In a perfect world, the thermostat opens and closes to maintain optimal engine operating temperature and cooling system efficiency. A 195-degree thermostat opens at 195 degrees. If your new Grill Master 5000 has a side burner, then testing the thermostat is easy. Drop a meat thermometer and the thermostat into a pot of water, light the fire, and watch. Make sure the thermostat opens wide at the rated temperature, usually stamped on the bottom. Use a thermometer in the radiator filler neck if you want to test the thermostat without disassembly of the system. It’s not a terrible idea to test a new thermostat to eliminate a variable before installation.

Belt Tightening Measures

belts and fan
Mike Bumbeck

As the water pump is the literal heart of the cooling system, inspect drive belts for cracks or glazing. Belt-driven water pumps might broadcast a bearing or gnashing noise before they go, but usually just suffer an instant catastrophic failure and spew coolant through the shaft. Give the cooling fan and blades a once-over to avoid whatever it was that happened to this fan we pulled from a parts car. An unleashed fan blade can cause all sorts of damage to the radiator, hoses, or anything else in its flight path. If the cooling fans and water pump are driven by electricity, check the electrical connections and test the motors.

Pressure Check

pressure test
Mike Bumbeck

The pressure test works as the first or last step in the cooling system check. Start with a pressure test if a leak is suspected, or finish up with a pressure test following repairs. Pressure test kits are out there, or you can make your own as shown using a drill, old radiator cap, tire valve stem, and assorted rubber bits. No compressor? No problem. A hand-operated bicycle or sports ball pump is a far safer bet than discovering what happens when you run 90 PSI into a cooling system rated for 13 PSI. Draw out some coolant, bring up the pressure, watch for leaks, listen for any gurgling sounds, and make sure the system holds at its rated pressure.

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