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Coolant leak on 2002 Explorer XLT V6 4.0L SOHC

Discussion in 'Stock 2002 - 2005 Explorers' started by dvictor, November 9, 2009.

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    1. wth

      wth New Member

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      Couple of notes about replacing the lower housing with "Rockauto.com" parts.
      1. The Dayco #72025 bypass hose will fit, but it's about a half inch to long, and needs to be shortened up on both ends, compared to the "Motorcraft" bypass hose.
      2. The STANT #25271 thermostat o-ring at $0.61 was a good fit/replacement.
      3. The hole in the new Motorcraft #RH 148 lower housing for the temp sender is slightly larger than the origional on my '02 Explorer. Since I didn't have a new o-ring or a new sender switch, it took 5 rounds of teflon tape to take up the slack and not leak. I'll switch it out next week.
       
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    3. nickorsi

      nickorsi New Member

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      City, State:
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      Year and Model:
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      I did this work over the weekend and it took me about 2hrs to get it all done. I do have one question. In the post #12 above, is that the heater hose in that picture? I had so much trouble disconnecting it, I ended up just cutting it off.

      I went to Autozone with hose in hand, and they dont have a listing for a heater hose in their system, so they gave me one that matched up as close as possible, and it has a slightly larger inner diameter. I cut it to size and clamped it down as tight as I could.

      I dont see it leaking, but dont want trouble down the road. Should I get the exact fit, and where would I get it?
       
    4. VORTMAX_99

      VORTMAX_99 New Member

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      City, State:
      Gorham ME
      Year and Model:
      2003 Sport
      Looking at the photos...I see what looks to be positions for the coolant
      temperature sensor and the temperature gauge sending unit. Am I
      correct in assuming the temperature gauge sending unit is the one
      still hooked up in the photos and the coolant temperature sensor location
      is the blank hole to the right of it?

      If I am correct in which unit is which...can you tell me how the coolant
      temperature sensor comes out? Looks like there may just be a clip that
      you pull and the sensor is sealed by an o ring...or is it a screwed in
      pipe thread ? If I go to change it...will I get coolant coming out of it
      or is the sensor mounted so it's just in a pocket where there is no
      coolant?

      Plan on changing it in the near future as have had a couple of cold start
      incidents where the engine didn't run right until it came up to temperature.
      and would like to know what to expect when I change it.

      Thanks for any info
      George
       
    5. clarks2001

      clarks2001 Active Member

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      City, State:
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      Year and Model:
      2002 Explorer Limited
      The little hole looking thing to the right of the temperature sensor is not really a hole. Dont ask me why Ford put it there (probably for the same reason they made the housing plastic). The temperature sensor I believe is also what sends the readings to your gauge.
      As far as yanking out the temperature sensor goes, dont worry about getting it out, just ditch it and pop a new one into the new housing. They are fairly cheap and come with the o-ring. I believe it screws off though. I had someone do it while they flushed my coolant (they offered to change the housings for free so y not lol).
      Changing it doesnt seem to have any noticeable difference in performance or starting or anything. I just dont smell heated coolant anymore and it dont leak lol.
       
    6. VORTMAX_99

      VORTMAX_99 New Member

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      Thanks for the info Clarks2001,

      George.
       
    7. clarks2001

      clarks2001 Active Member

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    8. JazzyJ

      JazzyJ New Member

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      This helped me very much. I was fortunate that I did not have to take anything off, just the hoses off of the thermostat housing. And since it had been leaking I did not have to worry about draining the radiator. No leakage after installing the new housing. Still have a slight smell so hopefully there is no other leak else where. I have been checking the fluid level and so far so good.

      Thanks all
       
    9. dvictor

      dvictor New Member

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      Year and Model:
      2002 Explorer XLT 4.0L
      Good to know that this thread has helped. I can't help but wonder how much it would have cost at the dealer to get this done.
       
    10. Tpayneful

      Tpayneful New Member

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      City, State:
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      Year and Model:
      2003 XLT 4x4
      I think that I have the same problem. I have a 2003 Explorer 4.0L. Mine popped on the way home today when I went to pass a slow car. It was spewing steam pretty good.


      [​IMG]

      It blew antifreeze all over the coil pack and and the intake so steam was coming from everywhere when I got to the side of the road. The back of the housing where the top and the lower housing meet have two small pieces that look like they blew out. You can see them on the picture. I think that I have the same problem as this thread. What do you guys think?
       
    11. Tpayneful

      Tpayneful New Member

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      City, State:
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      6 bolts, 3 hose clamps later and my lower thermostat housing was replaced. That was a real easy repair. This thread was a lifesaver! Total time less than 1 hour and less than $100 in parts.
       
    12. FAMILYMAN1981

      FAMILYMAN1981 New Member

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      City, State:
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      after taking my vehicle to a auto repair shop, i was told my explorer has the same thermostat issue and i will be replacing it myself following all the detailed information I received from this thread. (the shop wanted $700.00 for the repair.:thumbdwn:) my question is the gunk that is spewing from in between the cracks on the housing is also running down the top of my waterpump. should i assume i will need to change my waterpump also? and i thought i read that when filling the coolant once the job is completed i need to "leave the reservoir cap off" till the car warms up for the first time after repair is that accurate? any help would be greatly appreciated.
       
    13. Exproblems

      Exproblems Well-Known Member

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      >>>>>>>>>>>>>>>>>>>
      >>>>>>>>>>>>>>>

      If you have a 2003 Explorer with the 4.0L V-6 SOHC engine(same engine as my 2005 Explorer), then read the step by step instructions in the post link I provided below to change out your thermostat, gasket seal and coolant change. This is my post and I tried to give as much information to do this type of repair as I could. I did this same repair on my vehicle 2 weeks ago or so. Also, you do not need to change your water pump simply because coolant has leaked out of your thermostat housing and dripped down on to it. Only change the water pump if it is leaking fluid itself through the weep hole or if the water pump bearings are shot and squealing badly and leaking. You made need to change your serpentine drive belt if it has become saturated in coolant from your current leak from the thermostat housing. Coolant on the belt can cause it to squeal just like the sound that bad pulley bearings make. If you have any other questions of me on this repair, just ask, glad to help you if I can.

      http://www.explorerforum.com/forums//showthread.php?t=317658
       
      Last edited: June 6, 2011
    14. FAMILYMAN1981

      FAMILYMAN1981 New Member

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      thanks "EXPROBLEMS" I will use the guide found on this thread for my repairs, the detailed process is the only reason i will attempt this repair myself.thanks. the reason i was wondering about the waterpump is because my waterpump is located on the driverside of the vehicle and "shouldn't" be affected by the thermostat housing leaking because of the placement of the thermostat housing "passenger-center" of the engine. but i guess coolant would splash everywhere so i guess the waterpump is more than likely fine.

      anyway any advice on leaving the reservoir cap off once i fill the coolant after the repairs? is that the proper fill procedure?
       
    15. FAMILYMAN1981

      FAMILYMAN1981 New Member

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      "EXPROBLEMS" after re reading the link u sent i know understand the procedure. I appreciate all the help.
       
    16. Tpayneful

      Tpayneful New Member

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      When the thermostadt housing fails the coolant runs down the front of the engine. It looks like a failed water pump. I would only replace the water pump if it leaks after you have performed the thermostadt housing repair. It was one of the easiest repairs to do. Good luck!
       
    17. Exproblems

      Exproblems Well-Known Member

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      >>>>>>>>>>>>
      >>>>>>>>>>>>

      Which engine do you have? The 4.0L V-6 or a V-8 model? I have the V-6 and my water pump with attached cooling fan shaft and pulley is located in the middle of the engine, down below the thermostat housing area. FYI, They (water pumps) are usually centrally located on the front of the engine if a engine cooling fan runs off it's belt pulley connection. The serpentine belt spins the water pump pulley shaft, which activates the pumping action of the water pump and spins the cooling fan at the same time.
      You would get coolant splashing around by the cooling fan especially if you have a heavy or good size leak. This can make it hard sometimes to determine where the leak is coming from. A crudy build up around the seam of the thermostat housing is a tell tale sign that it is coming from there. When a water pump leaks, from my 34 year experience of driving cars, is usually right after you shut it off and pressure builds up in the system. Fluid will then drip or run out of the "weep hole" in the water pump for a few seconds or more and run down on to the Harmonic Balancer pulley and belt, then the ground. After you do the thermostat repair, check for leaks not only in the thermostat housing area, but then check the water pump area and below it. Use a flashlight for the water pump and I found it is easier to spot a water pump leak in darkness, because of the some what flourescent color of antifreeze and the flashlight hitting it.
      BTW, yes, you can leave the Coolant Expansion/Resevoir Tank cap off during the refill process and while you warm up the vehicle to get the thermostat open and don't forget to squeeze the upper radiator hose with your hands while it is warming up to work out any air bubbles in the coolant system. Air in the system will keep you from getting heat in the heater core till the air is purged out. I wore work gloves to protect my hands, hose gets some what hot and keep your fingers and hands away from the spinning cooling fan blades or fan belt. The upper hose should have an elevated section to it away from the cooling fan so you can get your fingers on it safely and squeeze. You'll see air bubbles after you squeeze it percolating up in the Expansion Tank, this is air escaping from the system. Make sure you measure how much coolant you drain from the vehicle, so you know how much new coolant and "distilled" water mix (At least a 50/50 mix) to install into your vehicle after the repair is made. Just follow those steps at your own risk of course, but it worked for me and no leaks to date or problems. You can also print that web page I gave you with the instructions on it so you can have them with you while you work on it. Good luck, let me know how it worked out for you.
       
    18. DrummerGeek

      DrummerGeek New Member

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      City, State:
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      My 99 Sport SOHC has had a *minor* coolant leak since I bought it 6 months ago. I now know that the leak was in the thermostat housing. The engine overheated for the first time about 2 months ago. I refilled it and everything seemed awesome. Then it almost overheated again a couple of weeks ago. This is when I finally found the leak because I realized it was getting worse. Once again refilled and tried to keep a better eye on it until I could replace it. Well, today was when the housing flat out failed. I had to have a dealership replace it due to time (not too bad cost wise though considering). I got to see the housing after they removed it, IT WAS PRACTICALLY SPLIT IN TWO!! The crack went from one sensor to the edge.

      The point of this post it to fix it as soon as you figure it out, because it only gets worse! Luckily the engine survived.
       
    19. Exproblems

      Exproblems Well-Known Member

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    20. DrummerGeek

      DrummerGeek New Member

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      Yes it was, so is the new one. However, I doubt it was the heat that caused the crack. I think more than likely it was the pressure on the already small leak. I think the problem was more due to the way the sensors were mounted.
       
    21. Exproblems

      Exproblems Well-Known Member

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    22. DrummerGeek

      DrummerGeek New Member

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      I definitely agree it was a shotty design.
       
    23. frankcal

      frankcal Active Member

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      Thanks to this thread I was able to find a Slow coolant leak I was having while pressing on the gas and overnight. The culprit was indeed the lower thermostat housing. I was going crazy looking for the leak for about a week before doing some intensive searching on here. Mine leaked in the same spot on the back of the housing where they're are 'glued' together. Couple hours later and $36 from oreillys my sport was no longer leaking. Glad I looked on here before replacing random things to just find out it wasn't it.
       
    24. 02X

      02X New Member

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      Thanks for all the help and tips! Just finished fixing mine.
       
    25. clusters4400

      clusters4400 New Member

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      had to same issue on mine, it was quite frustating because mine leaked in the very very very back where i couldnt see it, however when i replaced it the sensor it wouldnt fit snug...

      i know i should have replaced it, i did however find a "super low budget" fix, i smeared some rtb sealant and crammed it in there to make a good seal, made sure not to get sealant into the housing itself or on the sensor, made a snug fit and no leaks....all depends on your budget though!
       
    26. rmcknight

      rmcknight Active Member

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      its also very common for the plastic tubs on the sides of the radiator to leak. the leak is often very hard to find/see as it only happens in the transition period from cold to hot when the pressure starts to build and the seals have not properly sealed yet.
      you may see a leak about 5 min after starting for a min or so. the tubs can be tightened, but in the end a new radiator will be needed.
       

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