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How to: Replace a thermostat on a 2000 4.0L SOHC V6

AeroRamer

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'00 Limited
The following write up is for informational purposes only. This is just an account of what I did while troubleshooting an overheating anomaly (see thread here) on my 2000 Explorer Limited. As part of my T/S I removed the thermostat and took some notes and pictures along the way. I was not sure how involved this was going to be but it end up been very straightforward. It took me about 1.5 hours total to do this and another 15 minutes or so to test drive the Ex. Here is what I did:

Please note that this write up is for the removal and replacement of the thermostat for a 4.0L SOHC. The write up for the 4.0L OVH was done by 'Charlie' and can be found here.

Tools needed:
-Ratchet
-8mm socket
-10mm socket
-9/32" socket (the 7mm was a bit smaller and the 8mm to big)
-Pliers
-Paper towels or rag
-Small brush to scrape off some gunk and debris

First off, when I checked the repair manual, it said to drain the coolant out of the car. I did not have to do that. Since the thermostat sat on top of the block I thought that if there was some coolant it would be the coolant inside the upper hose, and that it would be minimal. So, I decided to go on very carefully without draining the coolant.

With the engine cool, using a ratchet and a 9/32" socket, I removed the four screws holding the plastic engine cover in place.


Next, using an 8mm socket, I loosened the clamp holding the air filter duct enough to be able to slide it off the intake body. After removing the electrical connector, and the two hoses that connected to it I removed the air filter duct from the Ex.









Using a 10mm socket I removed the top wire from the alternator (not sure if that is the ground or current and I did not check). I did this to get better access to the thermostat housing and the upper hose clamp. I also found it easier to work when I removed the electrical connector from the intake body.



Using a pair of pliers, I moved the clamp holding the upper hose to the thermostat housing out of the way. To move the hose out of the way I removed the 8mm screw that hold the hard plastic section of the hose to the engine block.



With everything out of the way there is now enough area to remove the three (3) 8mm screws that secure the thermostat housing. Note that there are only three screws and not four like I thought. Removing the housing cover give you direct access to the thermostat. To remove it just pull on it. I think I've read t that it is a good idea to notice the orientation of the thermostat and to install the new one in the same position. I am not sure about that but I did it anyway.





Before installing the new thermostat and gasket, using a couple of paper towels and a small brush, I cleaned both sides of the housing to remove gunk and loose debris. From the pic below you can see the discoloration from coolant that may have leaked from the hose or the housing.

Once the new thermostat and gasket was in place I re-installed everything in reverse order. Bleed (burp) the air out off the system and fill with coolant/water as needed.

Below is a pic of the old thermostat (left) and the new one (right). After a quick visual inspection I could not tell if he old thermostat was bad. One difference between both thermostats was the temp rating stamped on them. The old one (DFT) was rated to 197/223 degrees Fahrenheit versus 190/??? degrees for the new one (Stant, P/N 13649).


 


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section525

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Awesome write up! You V6ers have it so easy!! :D
 




ucluglee

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'00 XLT
Very nice. I should have documented when I replaced my thermostat housing, but it was 28 degrees outside and I wanted to get is done and back in the house.
 




AeroRamer

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'00 Limited
Glad you all like it. Just doing my part to help others as others have helped me in the past. It was a toasty 45 degrees here in North Florida. Needless to say it was too cold for my taste. I was trying to work as fast as possible to avoid working at night.
 




Hogitall

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98 XLT
My dilemma is that the thermostat housing keeps pushing the rubber o-ring gasket out of place and outside the sealing area (which I'm assuming you push it over the lip on the underside of the housing out towards the holes?) it keeps pushing out out of the sealing area when I try to tighten it down. Am I doing something wrong ?? Am I placing the o-ring gasket in the wrong place? And should I use gasket sealer? HELP!!
 




2TimingTom

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'97 XLT
This good:
5383217416_6be40ca0d5_z.jpg


This bad:
thermostat%20-%20old%20vs%20new.JPG
 




Hogitall

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OK..I think I have it now...Gasket placement issue..Hopefully it's good to go now..
 




jmazz8

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thanks for the help

Directions were very helpful...
I have a 1999 Explorer Sport and the layout is nearly identical.
Thanks!

:thumbsup:
 




LaRue

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I feel like a man again

Dude, Thanks for the how-to instructions. You saved me over a hundred smacks, drew in the neighbors with the hood up and the echoing rachet sound, and made me feel like the all-american macho male again. :usa:

I'm looking forward to the next project!
 




stevebr

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Yea! Your instructions helped!

I had just about given up. Went online and found this forum. Your instructions were great. The bolt holding on the plastic radiator hose bracket was what was holding me up. Thank you.

One comment. I think the wire you unbolted from the alternator was the Poistive side, not ground. I disconnected my battery before removing it for safety. Now I have to reset the radio stations! Bummer.

Thanks again.
 




6iron

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Toronto, ON
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'00 XLT
I wish mine was that easy... unfortuantely, a few months ago (for no good reason, of course), the hose connection on the top of the stat housing broke while on the highway. Coolant gone in about 1.3 seconds, and a lot of it hit the fan, so it was everywhere.

Replacing the entire housing was awful - they really don't design these to ever be taken apart again... getting at them is 75% of the work.
 




AeroRamer

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'00 Limited
Dude, Thanks for the how-to instructions. You saved me over a hundred smacks, drew in the neighbors with the hood up and the echoing rachet sound, and made me feel like the all-american macho male again. :usa:

I'm looking forward to the next project!

I had just about given up. Went online and found this forum. Your instructions were great. The bolt holding on the plastic radiator hose bracket was what was holding me up. Thank you.

One comment. I think the wire you unbolted from the alternator was the Poistive side, not ground. I disconnected my battery before removing it for safety. Now I have to reset the radio stations! Bummer.

Thanks again.



Glad I could be of service. I just uploaded the pictures to the forum so they are here permanently.

Thanks for the correction stevebr. I changed the sentence.
 




AeroRamer

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My dilemma is that the thermostat housing keeps pushing the rubber o-ring gasket out of place and outside the sealing area (which I'm assuming you push it over the lip on the underside of the housing out towards the holes?) it keeps pushing out out of the sealing area when I try to tighten it down. Am I doing something wrong ?? Am I placing the o-ring gasket in the wrong place? And should I use gasket sealer? HELP!!


For me it just fell in place. I did paid attention to the way the old one was oriented and installed the new one the same way. Maybe you are tightening to hard and pressing the o-ring out(?). Are you sure it is the one for your Ex?
 




Matie

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Explorer 2003 & XLT 96
Good Write -up Mate!

Just a question, I live in UAE , HOT HOT weather, most of the peoples just take of thermostate , what is the side effect, or it works fine,
My Fordy 96 had some problem in last winter,( when we say winter its mean around 22 to 26c somewhere!) so Garage changed Thermostate , now , in hot days tepmerature is normally statys above the middle , which is ok, BUT , I have noticed there is bit water leak & around the PLUG area, i dont know if its Cylinder head Gasket? anyway i am thinking to take off TS so car will not get much hot & pressureise the engine!! is this OK??
secondly how big job is to change that Gasket?

Regards
Matie
 




DoctorE

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2000 and 2003
This article is helpful. Thanks.

Another nice thing to have during this thermostat job is one of those “universal joints” to go with the ratchet drive extender. This will allow you to turn the bolts at a more comfortable angle. Most socket sets include one of these.
 




NorthernRebel

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2000 XLT
Thanks for the great pics. and instructions. I have a 2000 XLT with the 4.0 SOHC, and the thermostat housing just started leaking and went into overheating in a matter of minutes. I had bought a replacement housing from Advanced Auto. The whole upper and lower housing was manufactured by DORMAN. When we bought the part we showed the parts person that the part had a slight warpage in it. We were told that they all look like that. I had installed it, and in a matter of two weeks it started leaking worse then the original part. A word to the wise "When replacing the Whole Thermostat Housing and thermostat, CAREFULLY INSPECT the whole item where the sensors are installed and where the upper part joins the lower for warpage. And also the manufacture date of your vehicle, because there was a gasket change for vehicles built after 7/24/00. Thanks for all the wonderful info on this forum.
 




Racingtheburg

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1997 Limited
Mine was not this easy to access and I took the upper intake off to look for leaks and really easy access to the thermostat.
 




bar422

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Hey Racingtheburg......how did you get the intake off? I have to replace the thermostat housing in my 97 and am trying to figure out how to get it off without wrecking anything.
 




Racingtheburg

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Hey Racingtheburg......how did you get the intake off? I have to replace the thermostat housing in my 97 and am trying to figure out how to get it off without wrecking anything.

There are a couple of bolts and hoses. When you take the hoses off a good trick is to get the blue or bright green painters tape and put a piece where you took the hose off and number it 1 and put a piece on that hose that went there and label it 1 with a permanent marker. Keep doing this for all the hoses and even bolts it will make your life easier and I cant remember half the time what I did 2 hours ago lol.
 


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chaliceburn

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I can tell you how *not* to do this repair.

I did this job about three times in a row on my 2001 6cyl SOHC. First, they gave me the wrong thermostat, which I didn't realize because I hadn't taken it apart yet.

Then they said that the right thermostat didn't come with a gasket (in my case a simple rubber o-ring), so I decided to reuse the one already on it. It had slight damage but was reasonably intact. Drove it and pissed water all over the belt, fan, everywhere.

So I decided to half-ass it and slapped RTV all over the outer housing. Lasted about a day before it sprang a leak.

Then I got a new o-ring gasket and put it on, plus more even thicker layers of RTV, thinking that was the culprit. Nope. Peed all over yet again.

Finally I got a new plastic housing because the parts guy thought maybe I'd overtorqued the three screws and maybe cracked it. He was almost right. After taking my time (and scraping off a ton of RTV) and actually *looking everything over*, I noticed a tiny chip in the old housing 'lip' that sits on top of the o-ring. Right where it was pissing water. Duh.

moral of the story: take your time, pay attention to all the parts involved. No idea how that tiny chip got there, but that was definately the problem.
 




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