What’s causing a vapor smell and a film on my car’s windshield?
John Paul, AAA Northeast's Car Doctor, answers a question from a reader who is trying to solve a mysterious issue with his daughter's SUV.
Q. My daughter has a 2017 Toyota Highlander with 27,000 miles that’s still under warranty. At times, she and her husband have noticed a film on the windshield and have smelled some kind of a vapor. I looked into the overflow tank, and it was empty. I removed the radiator cap, and it was full. I ran the engine to warm it up, ran the fan, and tried to sniff the vents, and I couldn’t sniff anything. I rechecked the overflow, and it had two or three ounces of fluid. When the car was made, it probably had about 20 ounces of fluid in the bucket. Where did the fluid go? I’m trying to find out if the inside heater core has a tiny leak — before the warranty runs out at 30,000 miles. My nose is not good enough. Is there some kind of antifreeze sniffer, like the type that’s used for air-conditioning? I looked all over the front floor and found no sign of antifreeze.A. Over time, engine coolant will evaporate. When engine coolant is mixed properly, it is about 50 percent water, and the coolant in the overflow reservoir can evaporate. This is one reason why it needs to be checked and added to periodically. You could go back to the dealership and have a mechanic perform a pressure test of the cooling system. In this test, the system is put under pressure, and if over a period of time the system loses pressure, then there is a leak. The film on the windshield could be caused by outgassing of the plastics in the car. As the plastics outgas, this can produce an oily film on the windshield.
John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE certified master technician. E-mail your car question to [email protected].
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