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2005 V6 Mustang thermostat and housing replacement "how to with pics"

180K views 95 replies 43 participants last post by  amustangrocks 
#1 ·
Part 1:
the thermostat housing cracking and leaking seems to be a growing problem with the V6`s lately to cars with as little as 30k to 100k. at 65k i decided to replace all my hoses, stat and upper and lower housing as preventative maintenance. the hoses went as expected, then i had the problems others have faced with the sensor not fitting in the new housing and leaking.( teflon tape has been the bandaid) you need to buy the new sensor with the housing and it fits great.

when you go for parts:
a) get a new thermostat( this is the time to replace it)
b) upper and lower thermostat housings
c) 1- o-ring for the stat, 1- o-ring for under the lower housing( looks more like a rubber band than a o-ring)
d) new temp sensor

some of the pics were my first attemp, and i just did the hoses, and today i did the housing and 1 small hose off the bottom of the water pump that i forgot to buy last time.( the hose job is not included here)

1) make sure your car is cooled down. loosen the radiator cap on top and drain the coolant. the pastic wingnut valve is on the bottom corner of radiator on passenger side.( pic1)

2) remove you cai or air box from the TB while it is draining and move it out of the way.

3) remove the connector from the frt rt side of TB by sliding the red tab forward, then pressing the exposed spot and pulling forward. remove the 4 TB bolts. i think they are 8mm but a 5/16 works fine.(pic2) unplug the TB connector on the left side by squeezing and pulling and set the TB out of harms way.(see Note),(pics3&4) remove the upper radiator hose.
Note: if you have a 05, you have 2 cooling lines that need to be removed under the TB. i bypassed that before, now would be a good time to do the bi-pass if you havent yet. its not needed. heres a link to that job
http://www.allfordmustangs.com/foru...642-2005-mustang-t-b-coolant-pass-review.html

4) its alot easier to just remove the fan belt and idler pulley right now. you can use a 3/8" ratchet with a 1/2" socket on the tensioner pulley on the inside to swing the tensioner and remove the belt easily.(pic5) move the belt down a little out of the way and remove the idler pulley bolt, its a 15mm bolt, and set the pulley out of harms way.(pic6)

5) remove the small angle hose from the top of the stat housing.(pic7&8) and remove the temp sensor connector.(pic9)

6) loosen the clamps on the angle hose on the frt center lower stat housing. (easy to get to with the idler pulley gone) its almost off :)
 

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#2 ·
Part 2:

7) remove the 3-8mm or 5/16" bolts that hold the lower housing on.(pic10) and remove the housing assembly.(pic11)

8) remove the wire clip that holds the sensor in the housing. pry it out with a small screwdriver but watch where it goes if it flys off 10`away. push the new sensor into the new lower housing and install the clip. position the sensor so it faces the same way it did for the connector.(pics12.13.14.14.5)

9) install the new t stat in the lower housing in proper direction( long side down) and dip the o-ring in coolant and lay on top of stat.(pic15) set the upper housing in place and start the 3 bolts for the stat cover. tighten them each a little at a time till it is about seated to the lower housing. torque the 3 bolts to 89 in.lbs. or 7.4 ft. lbs.or 7.5ft lbs on the wrench.(pic16)

10) install the small frt elbow hose to the frt lower stat housing and clamp it on. you now have the new assembly ready to go back on. dip the o-ring that looks like a rubber band into coolant and slip into groove on bottom of lower housing.(pic17) note the bottom of the old housing. there were 3 plastic tabs that broke off(brittle) i was able to pic the pcs out of the block. (pic17.5)
 

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#3 ·
Part 3 ( the finish)

11) wipe the flat surface of the block where the housing sits clean(pic18) then carefully set the housing assembly in place.(pic19) install the 3 bolts and tighten equally till they are snug. torque the 3 bolts to 89 in.lbs. or 7.5 ft.lbs.

12) install the small top left elbow hose, plug the temp sensor connector in place. re-install the idler pully and torque to 35 ft. lbs.

13) connect the left wire connector to the TB and install the TB bolts tighteneing equally till seated.( the book suggests a new TB o-ring every time you take it off. ive had mine off a couple times, no new o-ring yet) torque the TB to 89 in.lbs. or 7.5 ft. lbs. connect the wire connector of the rt frt of the TB and slide the red tab back to lock in place. re-install your cai or intake tube.

14) look over all your work( hose connections ect) and close the drain valve at bottom of radiator. fill with coolant most of the way. squeeze the top radiator hoe to move air out and finish filling. you might do that a couple times while you are filling. start the car for a minute and then refill the coolant more if needed. install the radiaotr cap and run it with the heat on high till it is good and warm. doubhle check for leaks while its warm. you might loose a little blood doing this job(pic20) dont worry, you have plenty left for future projects:grinroll:
 

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#4 ·
Very good information

Thanks for sharing. Is there anything else that you would recommend changing while you've got everything out of the way?
 
#5 ·
Thanks for sharing. Is there anything else that you would recommend changing while you've got everything out of the way?
this is the perfect time to clean the throttle body if it looks dark or dirty inside while you have it off. use some clean rags and throttle body spray cleaner. work the butterfly and spray good around the shaft ends too.

its the perfect time to at the very least replace the small angle hose on the frt of the stat housing, and the one on top of the stat housing for peace of mind. the other hoses could be changed pretty easy without removing so much.

depending on your mileage and belt wear, it would be a good time to replace the fan belt.

if your crank pulley is looking bad, that could be done but thats a project in itself. take a good look at the rubber ring on the frt of the pulley. if its not smooth, its going bad. heres a link to that.
http://www.allfordmustangs.com/foru...2005-mustang-4-0-v6-crank-pulley-failure.html
 
#6 ·
pricing of the parts

a couple guys have pm`d me wondering about what the parts will cost. it seems that all the dealers have their own prices. but just to give some idea on the cost, this is what my dealer charged.

1) the lower housing...........49.06
2) the upper housing..........10.80
3) thermostat....................29.00 ( this would be cheaper at auto parts)
4) therm O ring..................9.60 ( cheaper at auto parts)
5) O ring housing gasket......4.74 ( note: these 2 O ring prices might be switched, since the descriptions on my statement dont tell much.)
6) sender ( temp sensor)....30.91
 
#7 ·
i think this should be put in the garage, with proper credits ofcorse, but thats a good how too, you beat me too it! i was gonna do it this spring.



but REMEMBER HOW THE CLIP GOES IN!

that $7.50 clip made the difference between covering up my fudge up in mi, and getting home with no questions asked. oh yea... and its hard to do with only channel locks lol.



some times on the TSTAT housings the sensor can leak, i used about 4 layers of Teflon tape and it sealed her right up.
 
#10 ·
well, i just went with the motorcraft from the dealer. i`m sure you could get a better price somewhere else. if your gonna do it, it would be a good idea to replace all these at the same time. thats why i did the hoses and the thermostat housing while i had it drained.
upper hose 27.38
lower hose 72.06
bypass to
to heater hose 6.00
a 3/4"heater hose
under altenator 12.95
frt bypass hose 38.39
 
#13 ·
yep, you could have done it for $0.00 labor charge. trying to do the writeup makes it look more involved than it is, but its really a pretty easy project, that if you take your time, a couple hours and its done. paying labor charges to me is mod and parts money down the drain. on a skill level 1-10, i would rate this about a 3 tops :)
 
#14 ·
So i remember posting on here a while back ago when i had first had mine replaced, But i have a question, It seems like my car is still consuming alot of the coolant way quicker than average. I've looked to see if i can see any leaks but nooooothing. I can kinda smell the coolant when the car heats up. What if its going into the engine bay??!?!?!?!?!?!?!?!?!? what do i do?
 
#37 ·
So i remember posting on here a while back ago when i had first had mine replaced, But i have a question, It seems like my car is still consuming alot of the coolant way quicker than average. I've looked to see if i can see any leaks but nooooothing. I can kinda smell the coolant when the car heats up. What if its going into the engine bay??!?!?!?!?!?!?!?!?!? what do i do?
If you see no sign of coolant leaking around the thermostat housing you may have a leak at the water pump which is also a common point of failure. Look close all around it. There is a small drain hole that may show signs of coolant which would mean it is leaking. Next would be a leaking head gasket. If it is an internal leak you would not see any coolant in the engine bay but you would also not smell coolant there. If it is an external leak you would see it around the cylinder head where it meets the block and you would smell it in the engine bay.
 
#15 ·
you should not be going through any coolant. if the thermostat housing and all the hoses look good, with no signs of leaks it could be your radiator cap leaking, or the plastic reservoir has a hole or crack. maybe swing back by the guy who did your thermostat and let him look at it.
 
#16 ·
unfortunately I've been at work all week and my next two days off will be until next weekend. But i did a quick look through everything in my car and nothing. Its not going super fast but its noticeable that its still going through fairly quick. The Radiator cap would be noticeable if it were leaking right? Just as well as the plastic reservoir?
 
#18 ·
Step 4 is a great tip - especially during reassembly. That lower clamp is virtually impossible to get positioned without completing this step.

The reason the sensor doesn't fit is that the O-ring has gotten old. A new O-ring and the old sensor works fine. The Ford dealer gave me one after I paid $60 for a new lower housing.
 
#23 ·
Yea, where did you get that hose from? Dealership would only sell the assembly ($80). I went to Oriely, and they had a part down, but they said it must be wrong since it was 3/4" hose and that was bigger then the hose that I brought in.
 
#25 ·
If you could do that that would be great :worship, or getting the name of the part so I can tell them what to look up. The dealer looked it up on their computer and said they don't sell the hose just the whole assembly. I can't see paying $80 for metal tubing that I already have that works fine. I just need the hose.
 
#28 ·
Ok, I found an exact match at the auto parts store. Luckily they let me browse through there assortment of hoses.

Here's the numbers off the hose. 20338, and C0338.

I got this at O'Reily's and the sku is PA 4856068.

Hopefully this saves someone $80.
 
#29 ·
thanks for the pm. thats cool that woked out good cause that would have been a real rip for 80.00. i did locate this part number from fords 2C5Z8A593CD (18472/BA) but also the lower hose that goes to the bottom of that metal tube assembly that i also replaced is 5R3E-18C266-BA C72GA. in a worst case, i think that short 90 upper hose could be cut from the lower one too
 

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#30 ·
Thanks for all the info!

After completion I found that there was still vapor coming from under the hood. I found that the sensor was leaking a bit of coolant and was under pressure and was whistling. I followed the instructions correctly, what do you guys think could be the problem?

Will the tape suggestion fix this? I did not replace my original sensor by the way.

thanks!

Chris
 
#31 ·
i would first try replacing the o ring on the sensor. next i would just get the new sensor. the tape is a band aid fix to get you home, but not a great thing. i dont know why they made some change in the replacement parts, cause my old sensor didnt fit the new housing at all. the new sensors fit perfect.
 
#32 ·
I want to say thank you to AMustangRocks for his contribution on this issue. I just got home after rescuing the little lady in her 05 V6 that was
"steaming." I found lots of coolant all over the top of the block causing the steam, but no big loss of coolant. The temp gauage was fine and I followed her home the last two miles with no issues.
Of course, it is raining here and this is our last night after two weeks vacation time off. (Why couldn't it have happened two weeks ago!)
We'll take it to the mechanic tomorrow but I still like to investigate myself. It's nice to be at the point in life where I don't have to fix things myself but I've never lost the desire to understand issues like this.
Thanks again and Happy New Year!

Todd :bigthumbsup
 
#34 ·
how do you get the clip back in for the sensor on the housing its a ***** to get back in?
 
#35 ·
just make sure the sensor is all the way down into the housing, there is a groove on the sensor that has to line up with the slots in the plastic housing that the clip goes into. the clip should push back in fairly easy. ( somehow this thread is stuck in the stickys, but still floating around the forum)
 
#36 ·
Nice writeup...

The Motorcraft brand thermostat housing is available from Rockauto.com for $32.79

The thermostat housing on the Ford 4.0 SOHC V6 is a true marvel of piss poor engineering! It is the last part in the world that should be made from plastic, and two pieces on top of that! It is exposed to heat, cold, pressure, chemical, vibration, and the mechanical stress of being bolted to the engine. They will eventually fail on every engine out there due to the nature of plastic and how it deteriorates over time. I am on my third one after 144,000 miles.

The two pieces are not actually glued together they are assembled using a process call sonic welding in which the parts are put in a fixture then exposed to pressure and very high frequency sonic vibration that causes the two sides to literally melt together.

Another area they are prone to leak is around the temperature sender that is fitted in the top. This is sealed with an O-ring which will fail over time and since the thermostat housing is a plastic part the O-ring sealing surface can vary quite a bit from on part to the next and can also change size over time which all lead to leaks. The O-ring is not available from Ford unless you purchase the entire sending unit but you can find one that may even fit better than the stock part at your local hardware store.
 
#38 ·
Nice writeup...

The Motorcraft brand thermostat housing is available from Rockauto.com for $32.79

The thermostat housing on the Ford 4.0 SOHC V6 is a true marvel of piss poor engineering! It is the last part in the world that should be made from plastic, and two pieces on top of that! It is exposed to heat, cold, pressure, chemical, vibration, and the mechanical stress of being bolted to the engine. They will eventually fail on every engine out there due to the nature of plastic and how it deteriorates over time. I am on my third one after 144,000 miles.


Another area they are prone to leak is around the temperature sender that is fitted in the top. This is sealed with an O-ring which will fail over time and since the thermostat housing is a plastic part the O-ring sealing surface can vary quite a bit from on part to the next and can also change size over time which all lead to leaks
thanks nice pony. man, aint it the truth about the outstanding quality job 1 design of the stat housing. and to think someone got a great salary with beni`s to come up with that.

i replaced my first one as preventive, around 50k and if i`m lucky i`ll do it again in the next 5,000 at 100k. that last one was so brittle the line up tabs broke off it when i opened it up. if your 3 for 144k, ive just been lucky so far. total cheap junk.
 
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