Engine Cooling System Maintenance: A Five-Point Check

Keep your car engine running cool this summer with this five point-check and instructions for maintaining proper coolant levels.

| May/June 1989

Car Cooling System Diagram

1. Petcock Drain: Open the valve fully when draining coolant and flushing the system. Close it finger-tight before refilling the system. 2. Hoses: Check for cracks, leaks, and damage from clamps. Squeeze them to determine their pliability. 3. Radiator Cap: Check coolant level and condition in non-recovery systems. Spring valves and gaskets should be in working condition. 4. Belts: Inspect all drive belts for cracks or exposed cords, and check tension. 5. Recovery Tank: Check the coolant level indicated at the marks. Draw hydrometer samples for condition and protection checks.


What's that? Summer's starting any minute and your mechanic says the car needs antifreeze? Sad but true; what once held sway as a winter ritual—draining the radiator and refilling the system with enough glycol to keep ice from forming—has now become a rite of spring, as well.

Antifreeze (or "coolant," depending upon your perspective) actually does several jobs. Sure, it still lowers the freezing point of water—that's to protect the engine block and other parts from cracking under the pressure of freezing, and expanding, water. But did you know it also helps raise water's boiling point? In the heat of summer, that quirk of physics can mean the difference between life in the fast lane and a stop on the shoulder.

Modern cars, you see, operate at higher temperatures than did vehicles of a decade or two ago. Pollution control devices, air conditioners, automatic transmissions and smaller, high-revving engines all put extra loads on the engine cooling system. However, water that normally boils at 212°F holds off for another 140° when it's mixed 50-50 with antifreeze. And that blend, when combined with 14 pounds of pressure in the system, won't start perking until reaching 263°F—enough of a temperature boost to give hardworking engines room to run without overheating,

But that's not all. A good coolant is only about 90% ethylene glycol. The remaining portion is made up of inhibitors that restrict corrosion—a reaction to the antifreeze itself that, without additives, would eventually clog the system with rust and sediment.

What You Should Know about Antifreeze

There's no question that the engine cooling system should get periodic attention—a look at the fluid level every few months and a coolant protection-and-condition check once a year. But there are a couple of other things you should know.

First, the price of antifreeze has increased—in some cases almost doubling since a year ago. Though this increase was most apparent last fall, when demand was high, there wasn't much mention of it in the press. If you're still curious as to the cause, blame it on a series of economic surprises.

mother earth news fair


Feb. 17-18, 2018
Belton, Texas

More than 150 workshops, great deals from more than 200 exhibitors, off-stage demos, hands-on workshops, and great food!