Thermostat housing problems. AGAIN.

[Ryan_289]

My wifes 05 Mountaineer has a coolant leak AGAIN. Ive replaced the lower housing. Then a few months later the upper housing started leaking. I replaced the housing and the orings. It appears that it is leaking again. I can see coolant in the manifold area and it is always on top of that thermostat housing. Its not a real fast leak. Sometimes I will see a wet spot under her car in the mornings and sometimes I wont. Im pretty sure it is leaking around the top housing again. I cant tell for sure if its leaking in the seam of the bottom housing or not. This is a pretty straight forward job, but is there something im not doing right? I used motorcraft parts from Oreillys. Is there a better option?

 

[Exproblems]

My wifes 05 Mountaineer has a coolant leak AGAIN. Ive replaced the lower housing. Then a few months later the upper housing started leaking. I replaced the housing and the orings. It appears that it is leaking again. I can see coolant in the manifold area and it is always on top of that thermostat housing. Its not a real fast leak. Sometimes I will see a wet spot under her car in the mornings and sometimes I wont. Im pretty sure it is leaking around the top housing again. I cant tell for sure if its leaking in the seam of the bottom housing or not. This is a pretty straight forward job, but is there something im not doing right? I used motorcraft parts from Oreillys. Is there a better option?

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I replaced my thermostat and O-ring back in May when I did a coolant flush and fill and I used a "Felpro-O-ring" I bought from Advance Auto Parts and no leaks at all. My original thermostat housing wasn't leaking , just replaced the thermostat and O-ring gasket as up dating maintenance. Did you tighten the thermostat housing bolts to the correct torque or could you have over tightened them possibly damaging the new O-ring you installed? For the V-6, the torque is 89 in lbs. For the V-8 up thru 2005 it's 18 ft lbs and for the V-8 2006 and later it's 97 in lbs.

 

[Ryan_289]

I dont have a torque wrench that goes down that low. I doubt I over torqued them. I only used a 1/4" ratchet to run the bolts down.

 

[Exproblems]

I dont have a torque wrench that goes down that low. I doubt I over torqued them. I only used a 1/4" ratchet to run the bolts down.

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A 1/4 inch torque wrench will do it. If you have a Harbour Freight Tools store near you, you can get one there for approx $21 or order one online from their web site. I got mine from a store near me. You probably didn't over torque the bolts as you said using the 1/4 in ratchet, I was trying to give you an idea as to why it started leaking again on you. Not really much there under the thermostat housing other than the lip on the housing where it meets up with the O-ring to form the seal. I was just reading on another thread today, from a topic a week or two ago, that someone had a similar leak to yours, but it wasn't the thermostat O-ring leaking, it was the seal under the aluminum base to the thermostat housing where it meets up with intake manifold. His name is Mike, but his screen name is different than that, can't remember what it is, but he posted pictures of the manifold with arrows showing where his leak is coming from. He also mentions how difficult it will be to repair, because he would need a new manifold and it would cost $600. You "may" have the same problem? His post should be on the board still. Good luck.

Update: I found that post you may want to take a look at. It's by "STLMACH1" and it's post #9 on this web page below.

http://www.explorerforum.com/forums/showthread.php?t=332712