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Coolant leak on 2002 Explorer XLT V6 4.0L SOHC

Exproblems

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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?
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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.
 
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DrummerGeek

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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.
 
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Exproblems

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. 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. >>>>>>>>>>>>>>>>>>>>

Was the t-stat housing on your 99 ES made out of plastic? They are on the 2002-2005 models. The hot temps from over heating most likely caused the crack. Can't understand why Ford made these things out of plastic instead of metal. The t-stats are easy to change and use only a slip-on rubber O-ring for the seal, no more paper gaskets and gasket sealer like on older model t-stat housings. Just have to tighten the bolts down with a torque wrench to specs. I changed mine last May, along with the coolant.
 
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DrummerGeek

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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.
 
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Exproblems

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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.[/QUOTE>>>>>>>>>>>>>>>>

The pressure and the heat would be connected during the overheating(steaming) you experienced and the combination of both would have caused the plastic housing to split apart. It's just a shotty design IMO.
 
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DrummerGeek

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I definitely agree it was a shotty design.
 
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frankcal

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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.
 
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02X

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

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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!
 
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rmcknight

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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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kaizo

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Hi,

I recently did this and replaced the whole thermostat unit. I have a very small slow leak where the thermostat sensor on top is placed in one of the two top holes with the push pin. It seems to be leaking where the push pin is. Have you had any problems with this? Should I be replacing the thermostat sensor? It was not leaking in that spot on the original part, only the lower housing was leaking on the original part. See attached link for the part that I bought.

2002 Ford Explorer XLT, 4.0L

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http://www.autozone.com/cooling-heating-and-climate-control/thermostat/dorman-thermostat/ford/explorer-4wd/2002/6-cylinders-e-4-0l-efi-sohc/165880_738647_0/
 
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dvictor

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hi there Kaizo,

i haven't had any related issues after doing the repair and haven't seen the problem you're having. I would change the sensor if you haven't already and make sure you get a new o-ring...that might help you out. it's been a while since I did the repair so i'm a little fuzzy on the details.

hope that helps,

Dwight...
 
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trucku

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LoKo498

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What kind of coolant are you guys using? The ford kind is really expensive. Also, why add distilled water and not regular water?
I'm about to do this repair next week!
 
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swshawaii

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^ See door pillar sticker for build date on your 2002. Also see usage notes on bottom of page 2.
http://www.motorcraft.com/servlet/B...here=1249081817307&blobcol=urlblob&blobkey=id

If the door pillar sticker is missing, click vehicle, enter VIN, and click minor features if desired.
https://www.etis.ford.com/vehicleRegSelector.do;jsessionid=BC5F9118C7D55EF6C72C7C18BF7560EE.fcvas509

If your vehicle requires Gold coolant, Zerex G-05 meets Ford's WSS-M97B51-A1 spec and is available mixed or unmixed at NAPA or O'Reilly stores.
http://www.valvoline.com/our-products/antifreeze-products/g-05-antifreeze-coolant
 
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