Thermostat Housing Weeping

[C420sailor]

Original housing was seeping at the cover/housing joint. Tried tightening the three bolts---no dice. Replaced the thermostat o-ring---same result. I assume the entire housing needs to be replaced?

RockAuto has the FOUR SEASONS 85331 housing assy pretty cheap. Anyone have any experience with it? Thanks!

 

[amberanger]

weeping

Mine had done that, but stopped. Keeping an eye on it just in case.

 

[C420sailor]

Unfortunately mine got worse. Even not under pressure I can see it oozing out. Antifreeze puddled in the valley under the intake manifold...pissed.

 

[swshawaii]

There is no fix besides replacing if the lower housing is splitting it's seams. Regarding Four Seasons or Dorman aftermarket, I've heard many more negative than positive usually due to fitment issues caused by sensor leaks.
Lower thermostat housings are by far the most common failure with the 4.0 SOHC's cooling system. There are
countless posts in the Gen 2 and ST forums alone. Here's a very worthwhile upgrade if you go with the OEM parts.

4.0 SOHC plastic thermostat housing
http://www.explorerforum.com/forums/showthread.php?t=239493

 

[XLTrunner]

Do NOT waste your money on the Four Seasons t-stat housing. I put that one in my '98 about 6 wks ago. Was trouble free for all of about 2 wks. I'll be pulling it out this weekend and replacing with the Motorcraft Lower housing (the upgrade using push-in sensors) and reusing the original upper housing.

Funny you mention leakage around the thermostat cover and lower housing. The Four Seasons replacement started doing that as well...along with other areas. I just posted a thread inquiring about proper 0-ring seal around the thermostat itself. The factory original seal is not a true 0-ring...rather, it has a square cross-section. Only thing I can think of is that it gives more sealing area for the cover than an ordinary 0-ring. Nobody has really chimed in on this, however...and, I'm still trying to find out if that style seal is even available anymore. One member on here says to use #2 Permatex on everything to help prevent leaks. I'm not thrilled with doing that, but I figure I've got one more shot at this before the weather turns cold.

 

[Maniak]

You can get a metal thermostat housing now.. AFAIK, [MENTION=209654]thermohousing[/MENTION] is still active here but he is the one who was making them and selling them on Ebay/Amazon.

~Mark

Edit: I think this is the right one for your '98 http://www.ebay.com/itm/1997-2001-Ford-Explorer-4-0-Metal-Thermostat-Housing-/301342159938

 

[C420sailor]

Copy all, thanks. Ordered the RH144 lower housing, push-in sensors, clips, and new seals. I look forward to removing my upper intake manifold...again...blegh.

The things I do for you, trucklet...and this is how you repay me.

 

[C420sailor]

Did the job. Pretty straightforward. Had to run to the dealer to pick up a housing-to-engine seal (RH614) as the new lower housing uses a newer, thinner seal---the normal '98 Ex one was too thick. No leaks, about $100 total and two hours of work!

Also used the DORMAN sensor clips vice the $$$ Ford ones. They worked like a charm.

 

[XLTrunner]

Likewise...installed the new Motorcraft housing w/original t-stat cap on mine and, after a 175 mile roundtrip today, no sign of leakage or pooling in the valley on top of the engine. It bears repeating...Four Seasons housing is a complete p.o.s.