2011 v6 Ford Mustang Automatic w/ 46k miles
I am losing coolant (the res level is very slowly going down when I check it over the period of a month) but:
- Not a drop under the car/no puddle
- Nothing under the dash/on the floor of the passenger side (no heater core leaking)
- Cannot smell any coolant from inside/outside the cabin when car is running or turned off
- Cooling system pressure test is fine and holds exact same pressure for 45+ minutes
- No white smoke out of the exhaust (besides the normal bit of steam in very cold weather or the little bit that goes away after the car warms up when you start to drive after a cold start)
- No oil in coolant
- No coolant in oil (no milky/wet/foamy oil)
- No coolant/water under bottom of oil cap
- Replaced res cap (radiator doesn't have a cap, the pressure is held at the res) with brand new Ford OEM cap
Any ideas? A pressure test would find a bad head gasket, right?
maybe you're just overfilling it. The extra will come out the overflow during driving.
You could try a UV dye leak detection kit
@mountainmanjoe Hmm, maybe. I am only filling it so its in-between the "cold fill range" though.
@mountainmanjoe
Didnt see the last part of your comment until now. UV dye might be my next move. Thanks!
@mountainmanjoe
Did you replace the radiator cap yet?
@Alan-S
He said in his question that it doesn't have a rad cap. Only reservoir cap.
By they way you should enter your own Answer instead of commenting on mine. Thanks.