tx_zstang

Well, the fact is, MOST of the time it is the thermostat housing. And water pumps are other likely suspects. But of course those are not the only possible source of a leak. You just have to find where it is coming from..could be a hose, could be the heated throttle body if on a '05, could be water pump... You my have to fill it up with water and run it to see where water is coming from. I've encountered many leaky hoses that leak under pressure when the engine is running, but at no other times.

Check above that bolt, the lines/hoses on the side of the engine, and yes, closely at the thermostat housing and temp sensor in the top of the housing.

kevinmalec

I replaced out the thermostat housing a year ago and is working fine. However, I now have a external head gasket leak, which is slowly leaking coolant onto my garage floor. Due to being external, the engine is not in jeopardy. I'm not worried about it, just the coolant leaking out and the smell is annoying. :/

yumazona

Update: Well everybody was hung up on the thermostat housing for good reason. That was my problem but I was too stubborn to believe it until I could see it. By looking for leaks with engine running and under pressure was deceiving on where the source was. Finally I got a radiator pressure tool on loan from AutoZone and with pressure built up with engine NOT running I was able to get into a position where I could first hear an air leak then finally see water bubbling out of a crack in the housing. Sure enough it was there but was not visible when pressure was released. Even once removed it looked good. Replaced it and resolved my problem. Air pressure also revealed a few hose leaks that were resolved with a few turns of the clamp screw or replacing factory clamp with a screw on clamp. I sure do appreciate everybody's help and suggestions on this site.
Thanks one and all!

kevinmalec

Good to hear it was an easy and inexpensive solution!

hunter226

I have a 2009 Ford Mustang base model. We've changed the thermostat, thermostat housing, temperature sensor, the water pump is good, new battery....stillll overheats. I was told it could be a clogged heater core, CCRM, head gasket (blown), or intake manifold. I cannot afford to get all these parts replaced. Is there anyone that's had this problem? It has 88,000 miles on it.

kevinmalec

I replaced out my thermostat housing/sensor and no leaks.

I have an external head gasket leak. It just leaks into the "V" of the engine and then eventually drips out onto the ground. Fortunately, I don't have any issues with overheating.

When you replaced the thermostat housing, did you flush out all of the coolant and then run water through?

Bitter

Glad you got it fixed, Yumazona. There are just some things that are so prevalent with these vehicles that we can't help pointing them out. Nine times out of ten the source of a coolant leak is the housing.

MrHall2015

Hey guys, great forum. My heater stopped getting warm a few weeks ago, I noticed the reservoir was low, added water, heater worked again, but the reservoir was back down in a few days. I read about the crappy plastic thermo housing, but couldn't see a leak anywhere & no drops in the driveway. Today, I FILLED The reservoir to the cold line, started the engin, almost immediately, it was dripping pretty fast underneath. I grabbed a jacked it up a bit, & grabbed a flashlight just to trace the drips directly to the same bolt from hell & did not see anything above it. Can anyone confirm that it IS indeed the crappy plastic thermo housing, even if it looks like the damn bolt!

JimC

It's hard to tell where that bolt is with that picture being a close up. Is it the alternator bracket? Looks like an engine mount maybe?

But water will run so more than likely it is the thermostat and it is simply running to the lowest spot to drip. You can see evidence of water flowing that way.

The thermostat housing usually splits on the back side. What does it look like around the thermostat housing?

MrHall2015

Yeah, sorry the pic is so close up. Its exactly like Yumazona stated "The bolt is attached to what looks like the engine mount and the bracket is holding the heater hose that comes off the water pump" crazy