Engine Coolant ThermoStat

In early 2019 & 19+ years, the FactoryOE ThermoStat Housing on my 2001 Ford ExplorerSportTrac started

to leak per the pics below; at first just an irritation, this leak steadily grew much worse. Under the Throttle

on the V6~4.0L~SOHC engines TopFront in several 1997~2012 models, the FactoryOE coolant ThermoStat

Housing is made of PPS Plastic, with SeparatelyMolded Lower+Upper parts joined using a Heated\Glued

flange seam, notorious for leaking. My housing leaked into the "Cave" atop the engine under the Manifold,

creating a smelly Coolant+Grime swamp. Various Ford part#s for the housings have similar LowerBodies;

UpperBodies vary with 1 or 2 ThreadMt or ClipMt Sensors; TopCovers vary with RightHi\RightLo\ForeWard

routed RadiatorHoses. After concluding any new Plastic replacement will want to leak as the factory part

leaked, I upgraded to an Aluminum TStat Housing 2019Aug; no leaks as of 2022May & another 10k+ miles.

Minimal skill+patience, several hours, a level shop floor & the basic items below are needed for this repair:

\* Hex+Torx SocketSet +DriverSet +Rachets +Adaptors +WrenchSet +SwivelExtensions
\* ChannelLockPliers +NeedleNosePliers +ViceGripPliers
\* WetVac +AirCompressor +Rags +Gloves +DrainPan +DisposalContainers +AbsorbantLitter
\* HiTemp RTVSealant 750f PermaTex# 27038.OptimumRed \ 700f PermaTex# 81878.UltraCopper
\* New Coolant
Parts & tools listed here are specificly for this Year+Make+Model ...; do not assume they fit your vehicle;

first verify your vehicle specs, closely inspect your engin & attached ThermoStat Housing, then confirm

chosen vendor part descriptions\recommendations are appropriate before purchasing\installing parts.

Time to replace other nearby parts: Hoses, Pump, RadiatorCap, Belt, Pulleys, Fan+Clutch, Tensioners..?

## Old TStat Housing REMOVAL+INSPECTION+CLEANUP

OLD TSTAT HOUSING Removal
\* Engin Cool, Set Brake, Chock Wheels
\* Disconnect Harness At BatteryNeg
\* Remove AirFilter~Throttle Duct
\* UnBolt Throttle Body From Intake
\* Disconnect Harness At Alternator
\* Remove FanBelt & IdlerPulley
\* Drain Coolant At RadiatorBottom
\* Remove Radiator~TStat Hose
\* Remove TStat Valv 3Bolt Cover
\* Remove TStat Valv & ORing
\* WetVac Coolant From Housing
\* Remove Core~TStat "L" Hose
\* Disconnect Harness At TempSensors
\* Remove Sensor Clips & Sensors
\* Loosen Pump~TStat Short Hose
\* Remove Lower 3Bolts & Housing
\* Remove Pump~TStat Short HoseOLD TSTAT HOUSING Inspection
\* Note Leak Stains From BodySeam
\* Note Broken Tab On EnginFlange
\*\* Tabs Are Not Needed, Cut Them Off !

OLD TSTAT HOUSING Assembly
\* Plastic Body Ford# 2L5z8592bb\rh144
\* EnginORing Ford#1L2z8255aa\rg614
\* 3ea EnginBolts Ford# w702527s437
\*\* M6x1.0x75mm\08mmHexHd
\* LowerHose Ford# f77z8548af
\*\* 1i300Diam 3i300Long BlkRubber
\* UpperHose Ford# 1L5z18472afM
\*\* 0i625Diam 5i000Long BlkRubber "L"
\* Sensor Ford# 3L8z12a648ba\dy1004
\*\* Gry2pin~Control 32f0c=104kOhm
\* Sensor Ford# 3f1z10884aa\ts390
\*\* Brn2pin~Gauge 32f0c=12kOhm
\* 2eaSensorClip Ford# w706800s303
\* Valv+ORing Ford# 2L2z8575aa\rt1167
\*\* 192f89c 2i625Diam 1i688+1i031High
\* TopCover Ford# 4L5z8592aa\rh165
\* 3ea CoverBolts Ford# w500015s437
\*\* M6x1.0x25mm\08mmHexHdOLD TSTAT HOUSING CleanUp
\* WetVac Broken Tab From Engin
\* WetVac \ BlowOut Coolant System
\* Clean EnginFlange+Area As Needed
\* Dispose OldCoolant + Rags + Litter
## New TStat Housing OPTIONS

Determined to not replace the old leaky part with a new leaky part, I found these options for improved housings. The aluminum ThermoStat Housing from SAS, pics & link below, appears the most rugid with Lower+Upper body machined as a single piece, minimizing potential for leaks; $130 ~ $160 depending on the accessories included. The SAS housing has EnginFlange guide tabs that can obstruct\break; bolts alone provide adequate alignment. The aluminum ThermoStat Housings from TAP \ SKP \ RAP \ GAP \ ZAB ..., pics & links below, appear alike as a group with Lower+Upper body joined by an ORing & 3Torx45Bushings, yet still an improvement vs the OEM part; $30 ~ $80 depending on accessories & vendor. SAS was too pricey for this "cheap bas'ard"; I chose the TAP kit with Valv +Sensors +Clips +ORings +Hose +Clamps +Bolts (less expensive SKP options became available later) then further improved this part with inverted TopBolts & RTV on the BodySeam +Sensor +EnginFlange ORings. After considering Threaded Sensors, I stayed with Clipped versions as room is limited under the IntakeManifold.

PICK ANY IMAGE ABOVE FOR A LARGER VIEW OR A VENDOR WEBLINK BELOW FOR MORE INFO.
\* TAP# -254 +250
\* SKP# SKRH144A\ SKRH144C
\* RAP# CT83Y8\ N654WN\ Q562KW
\* GAP# 18628-02010725\ 18628-02921819\ 18628-07741273
\* ZAB# ATK-8592-ACCS
\* SAS# SA3\ SA4 +SA5 +SA6 +SA7 +SA9
## New TStat Housing ASSEMBLY+PREP+INSTALL

NEW TSTAT HOUSING Assembly
\* Full Kit TAP# -254+250
\* Aluminum LowerBody+UpperBody
\* 2ea BodySeam+EnginFlange ORings
\*\* No Obstructing Flange Tabs To Break
\*\* RTV On Body+Engin+Sensors Added
\* 1ea TempSensor+ORing+Clip
\*\* Gry2pin~Control 32f0c=104kOhm
\* 1ea TempSensor+ORing+Clip
\*\* Brn2pin~Gauge 32f0c=12kOhm
\* 3ea Torx45 Bushings For BodySeam
\* 3ea 75mmLong EnginBolts
\*\* M6x1.0x75mm\10mmHexHd
\*\* Flat+Lock Washers Added
\* 3ea 25mmLong TopBolts
\* 3ea 50mmLong Inverted Substituted
\*\* M6x1.0x50mm\10mmHexHd
\*\* Flat+Jam+Lock Washers+Nuts Added
\*\* LockTite On Bolts@BodySeam Added
\* Pump~TStat Hose+Clamps
\*\* 1i300Diam 3i300Long RedSilicon
\* Core~TStat Hose+Clamps Added
\*\* 0i625Diam 5i000Long BlkRubber "L"
\* Aluminum TopCover For RH Hose
\* OldPlastic TopCover Fits If Needed
\* NoNameGeneric Valv+ORing Not Used
\* Stant# 13649 Valv+ORing 2019Aug
\*\* 192f89c 2i625Diam 1i688+1i031High
**\* Stant# 14748 Valv+ORing 2020Jun
\*\* 183f84c 2i740Diam 1i130+1i020High
\*\* LowerBypassDisc Ground Narrow**NEW TSTAT HOUSING Prep Step1
\* ORing+RTV On BodySeam
\* ORing+RTV+Clip In TempSensors
\* Snug 3 Bushings On BodySeam
\* Install Valv+ORing+TopCover, No RTV
\* Snug 3 Bolts & Nuts On TopCover
\* Allow 4Hr RTV SetUp

NEW TSTAT HOUSING Prep Step2
\* Torq 3 Bushings + 3 Nuts To 89InLb
\* Remove Valv+ORing+TopCover
\* Trim RTV FlashNEW TSTAT HOUSING Install Step1
\* ORing+RTV On Housing EnginFlange
\* Install Pump~TStat Red Hose+Clamps
\* Snug 3 Bolts & Housing To Engin
\* Install Valv+ORing+TopCover, No RTV
\* Snug 3 Nuts On TopCover
\* Allow 4Hr RTV SetUp

NEW TSTAT HOUSING Install Step2
\* Torq 3 Bolts + 3 Nuts To 89InLb
\* Connect Harness At TempSensors
\* Trim RTV Flash
\* Install Core~TStat "L" Hose+Clamps
\* Install Radiator~TStat Hose+Clamps
\* Connect Harness At Alternator
\* Install IdlerPulley+Belt+Throttle+Duct
\* Close Radiator Drain, Refill Coolant
\* Connect Harness At BatteryNeg
\* 15minEnginIdle With InteriorHeat On
\* Leak+GaugeCheck, 1hrCoolOff

NEW TSTAT HOUSING Install Step3
\* TopOff, Release Wheels+Brake
\* 15minDriveTest With InteriorHeat On
\* Leak+GaugeCheck, 1hrCoolOff

NEW TSTAT HOUSING Install Step4
\* TopOff, Drive Normally
\* Leak+Gauge+LevelCheck Routinely
**NOTE: Stant# 14748 ThermoStat LowerBypassDisc MUST BE GROUND NARROW slightly, to prevent jam open in the Housings throat & take advantage of 4RowAllAlumRadiators higher flow capacity.**

## New TStat Housing SENSOR CHANGE+MOVE

In 2020Jun, while changing the TimingChain Tensioner behind & left of this TStat housing, I removed the ClippedGray TempSensor on the TStat Housing, plugged that old hole, then drilled a new hole with a new ThreadedGray TempSensor as shown in the image below, improving clearance & access to the Tensioner.

NEW TSTAT HOUSING Sensor Move
\* ClippedGray~Control Sensor Removed
\* ThreadedGray~Control Sensor Added
\* Improves Access To TimingTensioner

## Links To Related Info

Thanks go to the brave souls who've preceded me in similar adventures & freely shared their experience:

https://web.archive.org/web/20200809115410if\_/https://www.explorerforum.com/forums/threads/possible-thermostat-problem-need-help.483910 Coolant TStat Replace
https://youtu.be/mAcwuhFOuuo?t=59 Coolant TStat Replace
https://youtu.be/Buyd-pMKQBk?t=78 Coolant TStat Replace

https://web.archive.org/web/20200514175645if\_/https://www.solvay.us/en/binaries/Ryton-PPS-Mold-Temperature-205305.pdf Coolant Leak: PlasticPPS Parts
https://web.archive.org/web/20200809115849if\_/https://www.explorerforum.com/forums/threads/sohc-v6-replace-rebuild-or-remanufactured.438266 Coolant Leak: TStatHousing Plastic
https://web.archive.org/web/20200301121249if\_/http://howtoreplacefordthermostathousing.com/index.html Coolant Leak: TStatHousng Plastic Replace
https://youtu.be/fYp7\_goQ2Qo?t=11 Coolant Leak: TStatHousing Plastic
https://youtu.be/z31LuE6KDdg?t=1 Coolant Leak: TStatHousing Plastic
https://youtu.be/4hna6iQHEw0?t=1 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/uUvlDJCreHc?t=1 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/CtogwA-ZJOw?t=1 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/lylAt1N\_IBI?t=1 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/93aOMZ8om4g?t=15 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/6TcVOKXpyOI?t=2 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/wqkFLCbZ0R0?t=63 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/t57b-0ScZCw?t=1 Coolant Leak: TStatHousing Plastic Replac
https://youtu.be/bEJ-poFSPwA?t=1 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/sX5IhlnxGe0?t=1 Coolant Leak: TStatHousing Plastic Replace
https://youtu.be/sxGRjzB0tkQ?t=10 Coolant Leak: TStatHousing Plastic Replace

https://web.archive.org/web/20200323011029if\_/http://www.naturecoastmustangs.com/articles/replacing\_thermostat\_housing\_on\_2005-2010\_v6\_mustang.aspx Coolant Leak: TStatHousing Alum Replace

https://www.sporttrac.org/search/7492435/?q=thermostat+leak&o=relevance Coolant Leak: TStatHousing Search
https://www.ranger-forums.com/search.php?do=showgcs&query=thermostat%20leak%204.0 Coolant Leak: TStatHousing Search
https://www.ford-trucks.com/forums/search.php?do=showgcs&query=4.0%20thermostat%20leak Coolant Leak: TStatHousing Search
https://www.reddit.com/search/?q=v6%204.0L%20thermostat%20housing Coolant Leak: TStatHousing Search
https://cse.google.com/cse?cx=partner-pub-1465533425503040:2946757341&q=thermostat%20housing&oq=thermostat%20housing&gs\_l=partner-generic.3...5849.9517.0.10110.0.0.0.0.0.0.0.0..0.0.gsnos%2Cn%3D13...0.3679j902503j18...1.34.partner-generic..0.0.0 Coolant Leak: TStatHousing Search

https://youtu.be/eK8X7HAbzzg?t=39 SerpBelt+BeltTensioner Replace
https://youtu.be/H4jXC4MiDZA?t=47 SerpBelt+BeltIdler Replace