mweiland

Brought my car in leaking coolant at the overflow tank cap. A problem was found with the cap (it would jump the threads before getting tight enough to click) and it was replaced.

A pressure test was performed and it passed. I drove the car home (about 25 min), popped the hood and it's leaking again worse than before.

Any ideas?

JimC

When mine did that it was a blown head gasket. The car never overheated, ran fine, and no oil in the coolant or coolant showing up in the oil. But every time I stopped the car that day it would blow coolant out of the reservoir

mweiland

Damn. No overheating here either. Oil is fine. Coolant looks fine. No exhaust smoke. No rough idle.

I had a similar problem a few years ago and it turned out to be a thermostat issue.

Seriously hope it's not a head gasket problem. 38k miles seems a little soon for something like that...

Art161

Let's start with the easy stuff first.

Have another pressure test done on the cap and the rest of the system.

Check the condition of the radiator filler neck. It's possible that the cap and the rest of the system could each pass pressure tests, but if the cap and filler neck don't mate properly for some reason, that could create the problem you describe.

Good luck.

mweiland

the neck seems fine visually. i won't be pressure testing it again until tomorrow, but...

i took it out today for about 20 min, shut it off and no leaks. drove it another 10 min and same thing, no problems at all.

i drove it another 10 min home and the same leak was back. but after sitting with it for a min poking around, i traced a slight hissing sound to the thermostat.

i'm leaning toward an issue with the housing or the thermostat itself at this point. maybe both.

still no oil smell or sheen in the overflow tank, nothing off with the oil cap or dipstick, no smoke, no power loss, no overheating.

Buckshot Barry

Bet it's the thermostat housing. Google it. Other V6'ers have reported the same problem.

mweiland

the car is in the shop now and they can't figure it out. they have a call in to ford engineering but still waiting on an answer.

the fan works but doesn't turn on when it's supposed to. works fine if you turn on the a/c.

IRON_monkey

06 mustang GT. I got the same problem too. It's going to shop tomorrow morning. What was your outcome?

Nuke

You may want to PM the OP. This thread is almost 2 months old and he may not be paying it any attention.