Coolant leak at thermostat

[sgtsandman]

Could be. I’m not sure what vehicle uses two on the 4.0 SOHC but apparently, at least one of them do. The aluminum ones I’ve seen have the space but aren’t drilled for the second sensor but others are.

 

[acsnowrider]

Only has one sensor. I've looked at it enough to know that one for sure. One sensor and a plug in another opening, next to the sensor, likely for another sensor?

Yes--My 04 had both sensors.

 

[G8orFord]

There are more than two housings. Some have one sensor, some have two sensors, some of the two sensor models are screw-in and some are push-in with an o-ring and a clip. My '01 has the two push-in style.

 

[JohnnyO]

Cracked t-stat housings are common on the 4.0 SOHC. Auto Zone has a HD Dorman unit, stronger than stock but still plastic, that's what I have since I was out of work when it cracked. You can get an aluminum unit from Amazon or Zabteck (http://www.zabteck.com/ ) that won't crack but cost more. Either way, get a 16 lb radiator cap for a '98-'00 Mustang V6 to lessen the odds it happens again.

 

[sunnyboy]

My replacement lower thermostat housing came with openings for two sensors, but a plug installed in one of them. (plug and clip). It was not in the same hole as what I was replacing, so I just moved the plug to the other hole before installing. I was actually very pleased that the kit had 'all the bits you need' including a new sensor o-ring and a new thermostat o-ring.

 

[JohnnyO]

My replacement lower thermostat housing came with openings for two sensors, but a plug installed in one of them. (plug and clip). It was not in the same hole as what I was replacing, so I just moved the plug to the other hole before installing. I was actually very pleased that the kit had 'all the bits you need' including a new sensor o-ring and a new thermostat o-ring.

Same with my Sport Trac.

 

[captainhero]

Hi, OP here
After double checking, i concluded it was really just the o-ring that was the problem, not the weld between the 2 parts that form the lower housing. I ended up getting the gooseneck, the o-ring and the thermostat as well to replace them all (truck has 100k miles so i thought it was worth changing the thermostat too).
Was not too bad to do, biggest problem was to put back the spring clamp on the radiator hose !
Hope it's good now !

 

[Jack Schmidt]

Zabteck (http://www.zabteck.com/

I'm also replacing my thermostat housing, 2003 with 129k miles.
Bought the Zabteck housing, looks great!
I've been trying to remove the old housing without removing the intake manifold but I'm about to give up and remove it. Any advice?

 

[JohnnyO]

I'm also replacing my thermostat housing, 2003 with 129k miles.
Bought the Zabteck housing, looks great!
I've been trying to remove the old housing without removing the intake manifold but I'm about to give up and remove it. Any advice?

Should pop right off. I didn't have any trouble. Check YouTube for a video.

 

[Jack Schmidt]

Todd at Zabteck pointed me to

Disconnect Battery, Drain Coolant, and Remove Air Intake Hose and Throttle Body

A Step-By-Step Guide to Replace the Upper and Lower Thermostat Housing on a Ford 4.0L V6 SOHC Engine

howtoreplacefordthermostathousing.com

Gonna follow these instructions right now.

 

[Jack Schmidt]

I finally finished replacing the entire housing (upper and lower).
It was a tedious job because I had to remove the two temperature sensors from the housing, insert the lower housing roughly in place, then reinstall the temperature sensors. There wasn't enough clearance to just install the lower housing and temperature sensors as an assembly.
Worse, when I removed the new sensors from the new lower housing I found that both sensor o-rings had been damaged when they were installed. Zabteck was very kind and sent me new o-rings, but when I installed them they felt like they would only hold a couple PSI, if that. I think I know why. Tight-fitting o-rings are easy to shear when installed, and I'm guessing Austekk found that the o-rings were getting sheared a lot and decided to loosen everything. In fact, the sensor seats are about 0.025" diameter larger than the original seats in the plastic housing.
I happen to have some thick rubber stock from Grainger, so I cut new tight-fitting o-rings with square cross section. They take up the play in the seats. I hope the rubber is resistant to ethylene glycol. I guess time will tell.
Other than the sensor o-rings trouble, the Zabteck housing is really nice, and it comes with sensors, thermostat, hardware, clamps, and a nice bypass hose.

 

[Kira]

One is the Coolant Temperature Sensor for the engine's management system. It's 5V.

The other hole is for the sender for the temperature gauge. It's 12V.