Thermostat 2 Sensors or 1?

[Kingfish]

Ford Explorerer Sport Trac 2005 XLT, 4.0 Liter, 6 cylinder.
Driving home steam started coming out of engine. Wife pulled over and called me. I replaced missing coolant and drove it home, about 4 miles. Next day, tracked the source of the escaping coolant to one of the holes for the two sensors on the thermostat housing. However, there was only 1 sensor. the second sensor was no where to be found. Further, I do not see any wiring that would connect to the second sensor. Perhaps there never was a second sensor, but rather, a plug?? Does this model require two sensors, or a plug in the second hole? Why would there be two sensors anyway? They both access the same water temp? Can I just get a plug, and the wire clip that holds it in place to correct this?


P.S. about 2 months ago, our battery overheated, due to a faulty Alternator, and blew acid all over the engine compartment. We replaced the Alternator, battery, Spark Plugs, Spark Plug Cables and a few other wiring items damaged by the acid. Work was performed by Ford Dealership. I don't believe they accessed the thermostat, but am curious, why whatever was in the empty hole of the thermostat is gone, whether it was a plug or a sensor.

 

[swshawaii]

Very unusual for the newer style o-ring sensors with metal clips to leak. 4.0 SOHC lower t-stat housings split at the seams and are an extremely common failure. 2004-05 ST's use only the ECT sensor with the gauge sender plugged. If you need to replace the lower thermostat housing use the single sensor RH148 housing. Keep in mind the old sensor o-ring will be flattened and not seal in the replacement housing. The DY1004 sensor must be replaced or a #8 o-ring may work.

Thermostat Housing Replacement
http://www.mysporttrac.com/shared/msgboard9e.asp?BOARDNAME=MSG&VIEW=1313020&SUB=1313024

How To Replace the Upper and Lower Thermostat Housing on a Ford 4.0L V6 SOHC
http://bengrosser.com/howto/fordthermostat/

 

[Kingfish]

Thank you SWSHawaii for the reply. Nothing appears to be damaged, the housing looks fine. There are just two manufactured holes in the housing, meant to have a sensor inserted into each. However, only one of the holes has a sensor in it, connected to a electrical cable. The other hole is just empty, i.e. if there was a sensor in it, it is gone. OR it possibly just had a plug in the hole. The retaining clip is gone as well.

I could go purchase a sensor and clip. Put it in the hole, and that would solve my leak. However, the sensor would in reality be acting as a plug, since there are no visible loose cables to connect to the sensor thus it wouldn't add any functionality other than a plug.

 

[swshawaii]

Do you know if the thermostat housing was ever replaced? Aftermarket Dorman uses a plug
and clip to seal one of the unused holes. OEM Motorcraft part has either one or two open ports.

http://www.dormanproducts.com/itemdetail.aspx?ProductID=53410&SEName=902-860

RH144 (Two Ports Open)
https://www.rockauto.com/catalog/moreinfo.php?pk=507928&jnid=2&jpid=0

RH148 (One Port Sealed)
http://www.rockauto.com/catalog/moreinfo.php?pk=379388

 

[Kingfish]

More info

You are correct about the two styles. Yes I did replace the thermostat, possibly housing, a few years back. Looks like I have the OEM Motorcraft housing with two ports one with a molded-in plug. I went to the Ford dealer and he showed me both. They are identical, with the exception of the plug. So I have to replace the entire housing, since it appears our battery acid explosion, and the way the plug is formed would have just had pooled acid on it, and ate through it, causing the leak. There is no way to plug that with standard parts, so I purchased another one and plan on replacing it this weekend. Wish me luck.
And again, thanks for you insight.

 

[Jonathan Powell]

Been a while since anyway replied here...

BUT...

I have a 2005 For Spor Trac 4.0 SOCH (POS!) that I just bought (Worst Mistake Ever!)

But I noticed last night that I have two holes, and one has a sensor, withe a pigtail, attached... The other just has a sensor, all along...


Is there suppose to be a pigtail connected to bothm or is one a plug?

House has writing on it. So I would say it's been replaces with one from a junkyard.

 

[swshawaii]

2004-05 ST's have only one pigtail, but had two sensor lower t-stat housings installed from the factory. Only wire is for the engine coolant temperature (ECT) sensor that also controls the temperature gauge on the dash. 2001-03 ST models had a separate gauge sender and wire. Apparently, Ford had some left over two sensor housings using an unwired sensor as a plug to seal the unused port. If replacing with an OE part, your best option is using the Motorcaft RH-148 one sensor housing. One less possible source for a leak, right?