As per posts over the weekend, have fixed a coolant leak. Refilled system and put a 75KPa cap on the tank. Either that cap was bad (made by "Sameer" in India) or I put it back on wrong. After holding just fine on a 75 mile test/shopping drive, it blew out a ton of water on a 4 to 5 mile test after topping up.

So, I put the original, German-made, Volvo-branded 150KPa cap back on. And, after topping up the coolant again, here is what happened:

After warm up and a 5 mile drive, last night, it leaked a little bit. Which I kind of expected, as the coolant expanded. But the level was below "Minimum" right after the test drive. Here is the funky part: As the car cooled, the coolant level went UP! Yes, UP in the expansion tank. Right back to where I had filled it to. Very weird, and apparently against the laws of physics.

Level was just fine this morning, with the car quite cold, about a half inch below "Maximum." After warming up on a 15 mile test drive, it was down low again, where it was last night after the above mentioned test drive. No signs of blow out or anything.

Isn't the coolant level in the expansion tank supposed to go **UP** as the engine heats up, then **DOWN** as it cools and both the coolant cools and the car sucks it back into the engine?

This is weird, and I'm quite uneasy about it.

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Scott Cook - 1991 745T, 1985 RX-7 GSL-SE, 1986 Toyota Tercel (Don't laugh, it is reliable, faithful AND gets 41 mpg!)