2006 GT - Coolant leak - Ford Mustang Forum
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post #1 of 5 (permalink) Old 4 Weeks Ago Thread Starter
Zenzak's Avatar
Joined: Nov 2016
Location: Columbus, IN
Posts: 17
2006 GT - Coolant leak


A few days ago, after drive approximately 15 miles (55mph with cruise control), I noticed when I stopped that there was a coolant leak on my car (2006 5-speed GT, 79800 miles), I opened the hood and noticed that the coolant was leaking from the expansion tank, between the tank and the cap (not through the cap valve).

The car was not hot (indicator on the dashboard was on the middle), I waited for the car to cool down, and put some coolant in it, about half of the tank was missing.

The next morning, I went to work with it, same road, 15 miles, when I arrived at work, no leak, coolant level was the same. I traveled for work so the car stayed on the parking lot for 3 days, today I went to pick it up and looked at coolant level first, again half of the tank missing. I put coolant again, and I let the car idle for 10 minutes in order to see if I was able to reproduce the issue.

So I notice that my fan is working correctly, the car did not heat up more than it was supposed to, and I couldn't reproduce the leak.

I left it on the parking lot for the week-end and I'm going to check on monday if the coolant level dropped again or not.

Do you have any idea where I should look first ? the car is not smoking, there is no weird stuff (like oil) in the coolant tank, the car runs totally fine, so I don't think (and I hope) that it's a head gasket issue.

Thanks for your help

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post #2 of 5 (permalink) Old 4 Weeks Ago
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Jeremy Weigel's Avatar
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Pull the dip stick to check for coolant in the crank case. If there is it will look milky. Check the water pump weep hole and area below the water pump for evidence of leaking (dried coolant residue).

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post #3 of 5 (permalink) Old 4 Weeks Ago
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If you observed the tank leaking, it's the tank. Replace it.

They are made of plastic and can get damaged and brittle. The plastic nipples also developed cracks where the hoses connect.

Tanks cost $35 to $50 at rock auto.

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post #4 of 5 (permalink) Old 3 Weeks Ago Thread Starter
Zenzak's Avatar
Joined: Nov 2016
Location: Columbus, IN
Posts: 17
Just got a tank from Rock Auto, going to change it tomorrow as I noticed a crack on the thread.

Thanks for your input
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post #5 of 5 (permalink) Old 3 Weeks Ago
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MustangLife's Avatar
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Originally Posted by Zenzak View Post
Just got a tank from Rock Auto, going to change it tomorrow as I noticed a crack on the thread.

Thanks for your input
Glad to hear you found a crack in the tank as that is much better than head gasket. Was there a large puddle under the car from where it leaked out while sitting for a couple days? Very odd, but sounds good. Would still check oil dipstick just to be safe! Also the caps are known issues as they get older.

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