Coolant System Fun!!!


New Member
Jul 29, 2017
Gentlemen and ladies, Jim here. Lifetime tinkerer, DIY guy, concert lighting dude. My Mustang is a silver 2010 V6 4.0L, plain jane silver, black interior, I love my girl.

I drive the mustang also for business trips, and this last one from Memphis to Oklahoma City I was driving home late at night and the engine kicked into overheat mode, I pulled over and found a coolant leak. Looked like it was from where the thermostat body is, so I filled the reclaim tank, and got her home.

I'm a child of an engineer, and I grew up working on my own cars, and I quite enjoy it, but this one is stumping me, and money is tight as heck so I'm trying to fix this so I can keep working... I've replaced the water pump myself, thermostat, and I thought I had it solved! Nope, my last business drive from OKC to Dallas, coolant leak, same spot -- right at the assembly where the thermostat lives.

I've taken a video if that will help -- unlisted YT link:

Would I be right in assuming that I have a leak in the thermostat housing itself and that I can replace it? It seems like once I drained the cooling system and re-tightened the thermostat housing, it might have postponed the leak somewhat, but when she got back hot again, leak. It's just a constant weep that is getting considerably worse, right around where that housing is, and I have got to fix this mofo in order to work!

I've got all day tomorrow to fix this thang, I've got an Autozone, O'Reilly, Pep Boys, AND anything else within ten minutes of me. What do you guys think?

New water pump installed!


Beautiful, the cooling channel, isn't it?


Just a fun photo of my work:

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Mustang Master
Jul 13, 2017
Ahhh! It's a "Drive by Wire"! Anyway, is the thermostat housing plastic? Have heard of them cracking. imp
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