General Maintenance: Coolant Change

The coolant in these engines should be replaced every couple of years. I use conventional green coolant which is getting harder to find. It seems in the US that there are only two manufacturers left for green coolant: Valvoline and Peak . And from what I can tell, Peak makes the Autozone, Advance Auto and O’Reilley in-house brands. Napa had the Valvoline coolant, but none of my local parts stores had the Peak coolant (probably because they want you to buy their in-house branded coolant).

To replace coolant, first remove header tank pressure cap

Stock, these cars have a long rod that connects to the radiator drain valve and runs to the top of the radiator. You could then open the drain from above the radiator. When I had the radiator rebuilt and re-cored, I had them replace with a standard drain valve.

Open the valve and there is no clear path for the coolant to drain so it runs off the suspension in many places and you will need multiple drain pans to collect.

I find it helps to jack up the back of the car when draining.

Once drained, close the valve and again it helps the bleeding process to now jack up the front of the car.

I used Autozone (Peak) green coolant and distilled water

Follow the service manual steps to fill and bleed the system.

Open bleed valve at top of radiator and fill per the instructions. Have patience because it fills slowly toward the end, and you may need to run the engine a couple of times to work the air out of the system and see constant flow from the bleed valve.

Once you drive and the engine gets hot, you will find that coolant expansion will force some coolant out of the overflow tube. The header tank does not have a site glass and filling it to the top is useless as it will force excess out when expanding so you need a way to know if you have enough coolant in there during regular checks. I use a dowel rod with a sharpie mark on it. After pulling it out of the header tank, the wetness level clearly shows the tank level.

Since I consistently use green coolant, and change regularly, I only do a coolant flush every 3 or 4 times.

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