I have a 2003 Mini Cooper S with 176K miles on it and recently the car started over heating in traffic and while stopped at traffic lights. I realized that it was basically out of coolant. I refilled the coolant and the car does not overheat anymore. I am noticing that in traffic there is a sweet steam like vapor coming out of the AC vents. I have a couple friends that are mechanics and they say it might be a leak in the coolant system or a leak in the heater core. Any ideas? I was thinking of trying to plug the issue by using the BlueDevil pour and go.

 

good place to start looking with an early GEN1 S is the coolant overflow tank ... they develop leaks at the seams. If on the back side it is hard to see. Coolant drips down on the heatshield immediately below and boils off ....




not very expensive ($20) and easy to replace ....

 

Thanks for your response! I filled up this tank that you show in the picture with coolant. My friend who is good with cars said that it was the place to put the coolant in. I did not see any other place to put in coolant. Also the day that I noticed that there was basically no coolant in the tank, there had been a lot of pressure build up and a white film was all over the tank. It had splattered all around the tank and down on the heat shield. When I went to fill up the coolant in this location I did not have a funnel so some of the coolant spilled on the heat shield and on the tank. Does this help any?

 

When I had that vapor coming from the vents I ended up needing a new heater core.

 

that is where you add coolant

if you spilled it hit the heatshield and under that is the exhaust so the spilled coolant cooked off ... what you need to watch for is potential leaks in the tank

if the smell goes away it was possibly just what you spilled

if it continues . . .

 

Pressure test cooling system, don't use sealer - Blue Devil or any other ones. Sealer is what an unscrupulous seller would do before selling you a leaky car.

If it's just the tank, consider yourself lucky.

 

 

Heater core

 

If it is your heater core you can bypass it where the heater hoses go into the firewall. This can buy you a little more time til the weather really gets cold.

 

heater core bruh

 

First off, hopefully you are not filling that tank to the top? White film might be the result of a bad head or head gasket. I would get a block tester and see if you are getting exhaust gasses in your cooling system. As far as your mechanic friends telling you to put a sealer in your cooling system, I would keep them as friends and let a real Mini Mechanic tell you what needs to be done.