Leaky Thermostat Housing or bad seal.

[Havfun]

Three and a half years ago I replaced my original Thermostat housing with the Dorman housing. I've had a lot of good performance from Dorman parts historically. That housing has about 57k miles now and I've got a slow leak. I can see coolant when hot (or when I pressurize the system) slowly coming from the interface between the housing and the manifold beneath it. I'm trying to determine if the problem is a bad seal or a bad housing or both. I attached a picture showing the problem. I don't see any cracks or signs of moisture on the housing or its seams but there is discoloration seen in the picture above where the moisture is seen. Were it not for the discoloration I would assume the seal is the only thing at fault. So, my question is does anybody know whether the leak is due to the seal or the housing??

 

[donalds]

For 2002-2010 Ford Explorer Engine Coolant Thermostat Housing Assembly 49455HT | eBay

***02-10 Ford Explorer 4.0 V6 Metal Thermostat Housing Made in the USA*** | eBay

I suggest don't use dorman unless you have no choice

A common fix is the metal housing

 

[Stiff]

Three and a half years ago I replaced my original Thermostat housing with the Dorman housing. I've had a lot of good performance from Dorman parts historically. That housing has about 57k miles now and I've got a slow leak. I can see coolant when hot (or when I pressurize the system) slowly coming from the interface between the housing and the manifold beneath it. I'm trying to determine if the problem is a bad seal or a bad housing or both. I attached a picture showing the problem. I don't see any cracks or signs of moisture on the housing or its seams but there is discoloration seen in the picture above where the moisture is seen. Were it not for the discoloration I would assume the seal is the only thing at fault. So, my question is does anybody know whether the leak is due to the seal or the housing??

View attachment 167564

I have replaced my 2006 Exp thermostat housing 3 times now I think due to it eventually leaking. It’s made of plastic and sits on a hot engine so eventually it will wear down. If you can buy the metal one, it is a lot more pricy compared to the plastic one but it should be a one and done solution.

 

[Havfun]

Thanks Stiff and Donalds. I'm suspicious that my housing is not leaking and that its the seal that is leaking based on the picture in the opening post. When I pulled the original housing I saw some pitting in the manifold area where the lower gasket sits. That made me real nervous but at the time I didn't think of installing the new part with RTV. I'm really not sure if the leak is due to the small region of pitting or if these seals just give way after a while. Either way, it makes no sense to pull this housing to fix the seal and not replace the housing especially since its 3.5 years old.
I would love to use the SimonsAuto metal part because i just don't want to do this job again. Presently SA has no stock on their part. The Chinese metal part (both parts are linked in post 2 above) has no user reviews that I could find so I'm a little hesitant to buy that one especially since I've heard good things about the SA part. I may have to wait for the SA part to come available. We'll see.

 

[donalds]

Thanks Stiff and Donalds. I'm suspicious that my housing is not leaking and that its the seal that is leaking based on the picture in the opening post. When I pulled the original housing I saw some pitting in the manifold area where the lower gasket sits. That made me real nervous but at the time I didn't think of installing the new part with RTV. I'm really not sure if the leak is due to the small region of pitting or if these seals just give way after a while. Either way, it makes no sense to pull this housing to fix the seal and not replace the housing especially since its 3.5 years old.
I would love to use the SimonsAuto metal part because i just don't want to do this job again. Presently SA has no stock on their part. The Chinese metal part (both parts are linked in post 2 above) has no user reviews that I could find so I'm a little hesitant to buy that one especially since I've heard good things about the SA part. I may have to wait for the SA part to come available. We'll see.

4.0 SOHC Metal Thermostat Housing Comparison
This may help

 

[MotorCityFats13]

you can always do the longer bolt and nut hack so it cant split at the seams anymore
ive had 0 issues since doing it.... last leak was the bypass hose... that tiny hose sucks

 

[Havfun]

4.0 SOHC Metal Thermostat Housing Comparison
This may help

Yes i saw that write up. Very good one for sure. Thank you.

 

[Havfun]

you can always do the longer bolt and nut hack so it cant split at the seams anymore
ive had 0 issues since doing it.... last leak was the bypass hose... that tiny hose sucks

I'm not familiar with that 'hack.' Do you have a link? Thanks.

 

[MotorCityFats13]

I'm not familiar with that 'hack.' Do you have a link? Thanks.

no i dont but its very easy... the bolts that hold down the top housing only go into nuts that are molded into the 2nd layer and leave the 3rd layer able to split and leak so you take the housing to the hardware store and find new bolts that will thread into the housing and extend enough to add nuts to the underside of the housing.... you then tighten the bolts and then tighten the nuts so they sandwich the 3rd layer to the 2nd and the 1st layer is held to the 2nd with the bolts..... the 3 bolts that hold the housing to the intake only have 2 layers so they hold but those other 3 are the weak point in the design when the housing is constantly heat cycled it splits..... I did this trick 4 years ago on a part i got from the salvage yard and no failures except for when my bypass hose split and replaced the junkyard part with a cheap ebay part when I changed hoses and reused my bolts from the first time

 

[Havfun]

no i dont but its very easy... the bolts that hold down the top housing only go into nuts that are molded into the 2nd layer and leave the 3rd layer able to split and leak so you take the housing to the hardware store and find new bolts that will thread into the housing and extend enough to add nuts to the underside of the housing.... you then tighten the bolts and then tighten the nuts so they sandwich the 3rd layer to the 2nd and the 1st layer is held to the 2nd with the bolts..... the 3 bolts that hold the housing to the intake only have 2 layers so they hold but those other 3 are the weak point in the design when the housing is constantly heat cycled it splits..... I did this trick 4 years ago on a part i got from the salvage yard and no failures except for when my bypass hose split and replaced the junkyard part with a cheap ebay part when I changed hoses and reused my bolts from the first time

Sounds creative! With the long bolts in place, can you replace the thermostat without removing the hsng?

 

[MotorCityFats13]

pretty sure one of the bolt/nut combos are hiding so i would throw a new t-stat in there for giggles but removing the whole housing is easy just not the hose clamp on the bypass hose if you dont set it in the right place when you do the install

 

[Havfun]

It looks like my housing sprung a real leak yesterday. Not 100% sure its the housing but close enough to move on replacing it. I learned of Motorcraft RT1220 from this thread: Anyone Tried Motorcraft Metal Thermostat Housing?
I attached a pic of this Motorcraft RT1220. A few days ago rock had it for $105 but not today. It can be purchased locally at O'reilly for $127-. It looks like a nice part to me and even a little less $ than the SA part. For me the cost delta between the three metal housings is not an issue. I'm inclined to go with the RT1220 unless someone has some reason to think one of the others is better. Any comments before I jump on and buy it?

 

[Havfun]

Just wanted to follow up on my thermostat housing leaks. I confirmed that the Dorman plastic housing was the cause of the leaking I mentioned in post #12. Dorman was very good about it and gave me a full cash refund based on their lifetime warranty. Very good service on Dorman’s part for sure. I purchased the metal housing from Simmons Auto. Dealing with Jonathan was a pleasure. While I preferred to install it myself, I had to take it to the local repair shop to do the installation because of a shoulder injury. It’s a nice housing and I don’t expect to have any problems with it. That said, there is a very, very slow leak between the main cooler hose and the housing hose outlet. The outlet of the housing is a rough surface casting (not smooth machined) and this may be contributing to the issue. It should be correctable by using a new hose clamp or re-positioning the hose clamp or going to a screw type clamp none of which I’ve tried yet. Eventually I’ll get around to it but the leak is more cosmetic than anything else. I attached some pictures from before and after the installation.

 

[Lukas2009]

I'm not familiar with that 'hack.' Do you have a link? Thanks.

New coolant thermostat housing question

 

[Havfun]

Thanks Lukas2009 for the link to that great thread!
BTW, the very slow leak or seepage I mentioned in post #13 seems to have self-corrected with no intervention on my part! Looks like all is well now so I'm real happy with the SA metal housing and the way the repair turned out. Finally the coolant level in my expansion tank is rock steady and there is no coolant odor wafting from my grill!