My 2000 Ford Windstar has a coolant leak. What could be causing it to leak?

It has two leaks. One is from the passenger side near the front tire and the second is right below the driver's seat. I have to replace the coolant after I have had the heater on for a bit. I never have it on for more than 15 min. Not because the coolant runs out in that time but I just don't use it for long.

I took it to the mechanic and he stated it was the "lower intake manifold gasket". I'm asking if anyone has any other ideas because that repair is pretty pricey.

You took it to a mechanic who actually SAW the vehicle and made a diagnosis, but you want us to tell you something different?

Okay, it's quite possibly the connection at the coolant quadrant on the muffler bearing lock-out device. No problem. That is repaired with duct tape. Takes about 5 minutes, and any mechanic will do it free of charge!

Hi till the leak is fixed it is never going to work properly. The heater will never actually give any heat either.