In early 2019 after 19years plus, the FactoryOriginal TStat housing on my 2001 Ford Explorer Sport Trac began to leak per the pics below; at first just an irritation, this leak steadily grew much worse. Under the Throttle on the TopFront of V6~4.0L~SOHC engines in several 1997~2012 Ford models, the Factory\OEM coolant ThermoStat housing is made of PPS Plastic, with the 2 SeparatelyMolded Lower+Upper parts joined using a Heated\Glued flange seam, notorious for leaking. My housings rear leaked into the "Cave" atop the engine under the Manifold, creating a smelly Coolant+Grime swamp. The various Ford part#s for these housings have similar LowerBodies; UpperBodies vary with 1 or 2 Threaded or Clipped Sensors; the TopCovers vary with RightHi\RightLo\ForeWard routed RadiatorHoses. After concluding any like Plastic replacement part will tend to leak just as the factory part leaked, I upgraded to an Aluminum TStat housing in 2019Aug with no leak as of 2021Feb & another 10k+ miles.
Minimal skill+patience, roughly 2 days, a level garage floor, & these basic shop items are needed for this repair:
- * Hex+Torx SocketSet +DriverSet +Rachets +Adaptors +WrenchSet +SwivelExtensions
- * ChannelLockPliers +NeedleNosePliers +ViceGripPliers
- * WetVac +AirCompressor +ShopRags +PlasticGloves +DrainPan +DisposalContainers +AbsorbantLitter
- * RTV Sealant, 700f371c Permatex#UltraCopper Recommended
- * New Coolant, 2Gallons 50%EG 50%H2O Recommended
Parts & tools listed here are for this specific vehicle 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 making purchase & working on your vehicle. Time to replace any other nearby parts: Hoses, Pump, RadiatorCap, Belt, Pulleys, AC\FanClutch, Tensioners..?
Old ThermoStat Housing REMOVAL+INSPECTION+CLEANUP
* 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 Hose
* 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
* 2ea SensorClips Ford# w706800s303
* Valv+ORing Ford# 2L2z8575aa\rt1167
** 192f89c 2i625Diam 1i688+1i031High
* TopCover Ford# 4L5z8592aa\rh165
* 3ea CoverBolts Ford# w500015s437
** M6x1.0x25mm\08mmHexHd
New ThermoStat 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 ThermoStat Housing ASSEMBLY+PREP+INSTALL
* 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
* 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 Flash
* 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
New ThermoStat Housing SENSOR CHANGE+MOVE
Old ThermoStat Housing REBUILT
A few months after installing the new Aluminum TStat Housing, while doing some garage cleaning I came across the old Plastic TStat Housing; almost to the trash can, a question came to mind: might the Plastic BodySeam be taken apart & a root cause of the notorious leaks determined? After some 2hrs of gentle work with a razor knife, keyhole saw, brass brush, grinder..., the Lower+Upper body pieces were separated & cleaned, revealing a very weak GlueJoint\HeatSeal. Furthering this whim, pictured below is my ReBuild of the Plastic Housing as a backup. While I would trust this ReBuild more than a new Plastic Housing, an Aluminum Housing remains the preference.
* EnginBolt MetalSleeves Ground Short
* EnginFlange Tabs Not Reqd, Removed
* TopBoltsInverted +JamNuts +LockNuts
Links To Related Info
Thanks go to the brave souls who've preceded me in similar adventures & freely shared their experience below:
- https://youtu.be/CXK6qNaJWBs?t=401s Coolant SystemLeak+PressureTest
- https://youtu.be/wwOmoYgIYSE?t=20
- https://youtu.be/fYp7_goQ2Qo?t=11
- https://youtu.be/z31LuE6KDdg?t=1
- https://youtu.be/4hna6iQHEw0?t=1
- https://youtu.be/uUvlDJCreHc?t=1
- https://youtu.be/CtogwA-ZJOw?t=1
- https://youtu.be/lylAt1N_IBI?t=1
- https://youtu.be/93aOMZ8om4g?t=15
- https://youtu.be/6TcVOKXpyOI?t=2
- https://youtu.be/wqkFLCbZ0R0?t=63
- https://youtu.be/t57b-0ScZCw?t=1
- https://youtu.be/Buyd-pMKQBk?t=78
- https://youtu.be/mAcwuhFOuuo?t=59
- https://youtu.be/eK8X7HAbzzg?t=39
- https://youtu.be/H4jXC4MiDZA?t=47
- https://youtu.be/bEJ-poFSPwA?t=1
- https://youtu.be/sX5IhlnxGe0?t=1
- https://youtu.be/sxGRjzB0tkQ?t=10
- https://web.archive.org/web/20200809115410if_/https://www.explorerforum.com/forums/threads/possible-thermostat-problem-need-help.483910
- https://web.archive.org/web/20200809115849if_/https://www.explorerforum.com/forums/threads/sohc-v6-replace-rebuild-or-remanufactured.438266
- https://web.archive.org/web/20200301121249if_/http://howtoreplacefordthermostathousing.com/index.html
- https://web.archive.org/web/20200323011029if_/http://www.naturecoastmustangs.com/articles/replacing_thermostat_housing_on_2005-2010_v6_mustang.aspx
- https://www.sporttrac.org/search/7492435/?q=thermostat+leak&o=relevance
- https://www.ranger-forums.com/search.php?do=showgcs&query=thermostat%20leak%204.0
- 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
- https://www.ford-trucks.com/forums/search.php?do=showgcs&query=4.0%20thermostat%20leak
- https://www.reddit.com/search/?q=v6%204.0L%20thermostat%20housing
- https://www.solvay.us/en/binaries/Ryton-PPS-Mold-Temperature-205305.pdf
- https://web.archive.org/web/20200920100659if_/https://www.explorerforum.com/forums/threads/stop-leak-coolant-additive-which-one.489558 Coolant Leak Fix: K-Seal