98 Ford Taurus…
- Car overheats and coolant leaks from overflow cap in hot weather, when air conditioning is turned on.
- Overflow tank and cap is new.
- Coolant leaks if I’ve added it up to the fill line. Leaks occur soon after parking.
- Coolant always looks fine, no changes in color or consistency.
- Radiator fans DO turn on when A/C is turned on.
Last year I noticed that my coolant was leaking somewhere around the overflow tank. The level would stay low even after adding and the car would overheat in 90 degree weather. I found that there was a large crack in the tank, so I got a new (used) one. The problem persisted and I determined that the coolant was purging from the cap, so I got a new one. The new cap did not seem to fit snugly, so I got yet another new one. By this time, it was fall and even though the coolant level would stay well below the refill line in the overflow tank, the car would not overheat.
Now it’s summer again and the car overheats in hot weather when the air conditioning is on. Also, if I add more coolant, it will again purge from the cap until there is only about an inch in the reservoir.
It’s almost as if the pressure is too great for any cap (rated 15psi). The car is not exhibiting any other symptoms.
Any suggestions for a novice shade-tree mechanic that does his best to solve problems on his own?
Thank you in advance!