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Bad Radiator Cap?

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Just want an opinion...After every drive I have less coolant in my overflow tank. Lately the area under the rear trunk that seals the radiator fill area has had moisture. I'm assuming this means some water vapor is leaking from the pressure cap. I am going to buy the "new" cap since after reading many posts on this site it has been determined that the "new" cap is better. So, does anybody think this is where my "leak" might be? Also...what is the tiny pull-up lever located just to the front of the radiator cap? Is this the pressure relief valve? If so, after opening this valve I never hear any pressurized air escaping...thoughts?

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I replaced the coolant cap with the new ".01" style and after driving 70 miles yesterday the coolant in the tank stayed steadly between the low and high marks on the overflow tank. Also, there was NO moisture on the underside of my rear trunk lid! I now believe the old style coolant cap was allowing some water vapor to escape. Soooo, if you are loosing small amounts of coolant at a time and have the old cap, go spend the $20 bucks and try the new cap first. This very well may be your problem! :clapping:

Thanks to all for the opinions!

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