Coolant leak on 2002 Explorer XLT V6 4.0L SOHC

dvictor · 11-12-2009, 11:52 PM

Interesting. When I started up the Explorer after work today the "Service Engine Soon" light turned itself off. Cool.

wth · 12-08-2009, 09:32 AM

I did this repair last weekend......B4 I saw this thread. Long story short: I'll be replacing the lower housing this weekend, along with another lower seal, oring, and another bypass hose, just to be on the safe side.
Thanks for the pics, as after I replaced everything but the lower housing, I soon discovered the seeping along the backside where the 2 piece lower housing is "glued" into one piece.

nickorsi · 12-08-2009, 10:15 AM

I just got my parts in. I am very glad that someone introduced me to RockAuto, best deal on parts hands down.

Now to my question.

I got my upper and lower housing,new thermostat and thermostat seal, but is there another seal that I need? I thought I read in a post there is a seal where the lower housing connects to the engine block.

Also, when I replace the coolant, do I just fill up the overflow tank, since there is no access to the radiator? Just got this Mountaineer, to replace my 98' still trying to figure out everything on it.

Thanks!

clarks2001 · 12-08-2009, 08:30 PM

yeah, its for the housing to intake seal. Its definitely needed. Its not expensive...like $4 bucks at most. I bought mine from the parts counter at Ford. Its not like the o-ring that goes to your thermostat housing. it is like 1/4 inch wide (cant remember off the top of my head) and like an inch circumference. I would suggest a new coolant temperature sensor while your at it. those should come with the o-ring already (mine from autozone did)

wth · 12-10-2009, 03:06 PM

Quote:

Originally Posted by clarks2001

yeah, its for the housing to intake seal. Its definitely needed. Its not expensive...like $4 bucks at most. I bought mine from the parts counter at Ford. Its not like the o-ring that goes to your thermostat housing. it is like 1/4 inch wide (cant remember off the top of my head) and like an inch circumference.

That IS an interesting seal, as it looks like a 1/4" wide X 1.5" dia rubberband. The interesting part is that it slips easely up into that groove in the bottom of the lower housing, but the groove is bigger than the "rubberband seal". When you look at it, it looks like it would not seal very good.

wth · 12-13-2009, 10:51 PM

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.

nickorsi · 12-14-2009, 12:34 PM

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?

VORTMAX_99 · 12-17-2009, 02:48 AM

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

clarks2001 · 12-17-2009, 10:55 PM

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.

VORTMAX_99 · 12-20-2009, 05:50 PM

Thanks for the info Clarks2001,

George.

clarks2001 · 01-20-2010, 05:46 PM

Ok, so why did ford make the thermostat housing out of plastic? This isnt as bad as the last one but it really makes me mad because I just bought it on October 21, 2009 and didnt get around to installing it until December (yeah I know, I am lazy lol) and its already leaking.
Pics are the first 4 images:
http://s467.photobucket.com/albums/r...t=DSC00358.jpg

JazzyJ · 08-11-2010, 07:34 PM

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

dvictor · 08-11-2010, 08:54 PM

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.

Tpayneful · 03-23-2011, 07:28 PM

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.

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?

Tpayneful · 03-25-2011, 09:53 PM

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.

FAMILYMAN1981 · 06-06-2011, 12:26 PM

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.

) 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.

Exproblems · 06-06-2011, 01:38 PM

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

Quote:

Originally Posted by FAMILYMAN1981

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.

) 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.

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

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/...d.php?t=317658

FAMILYMAN1981 · 06-06-2011, 03:15 PM

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?

FAMILYMAN1981 · 06-06-2011, 03:20 PM

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

Tpayneful · 06-06-2011, 06:33 PM

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!

12-08-2009, 10:15 AM	#23
nickorsi Wannabe Elite Explorer Cumming,Ga 05 Mountaineer Join Date: Mar 2007 Posts: 31 Vehicle Specs	2005 coolant leak I just got my parts in. I am very glad that someone introduced me to RockAuto, best deal on parts hands down. Now to my question. I got my upper and lower housing,new thermostat and thermostat seal, but is there another seal that I need? I thought I read in a post there is a seal where the lower housing connects to the engine block. Also, when I replace the coolant, do I just fill up the overflow tank, since there is no access to the radiator? Just got this Mountaineer, to replace my 98' still trying to figure out everything on it. Thanks!

06-06-2011, 12:26 PM	#36
FAMILYMAN1981 Wannabe Elite Explorer sacramento '03 xlt v6 Join Date: Jun 2011 Posts: 3 Vehicle Specs	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.) 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.

11-12-2009, 11:52 PM	#21
dvictor Wannabe Elite Explorer Honolulu, HI 2002 Explorer XLT 4.0L Join Date: Nov 2009 Posts: 16 Vehicle Specs (Original Poster)	Interesting. When I started up the Explorer after work today the "Service Engine Soon" light turned itself off. Cool.

12-08-2009, 09:32 AM	#22
wth Wannabe Elite Explorer Join Date: Mar 2009 Posts: 17 Vehicle Specs	I did this repair last weekend......B4 I saw this thread. Long story short: I'll be replacing the lower housing this weekend, along with another lower seal, oring, and another bypass hose, just to be on the safe side. Thanks for the pics, as after I replaced everything but the lower housing, I soon discovered the seeping along the backside where the 2 piece lower housing is "glued" into one piece.

12-08-2009, 08:30 PM	#24
clarks2001 Wannabe Elite Explorer Ashburn, Virginia 2002 Explorer Limited Join Date: Apr 2008 Posts: 203 Vehicle Specs	yeah, its for the housing to intake seal. Its definitely needed. Its not expensive...like $4 bucks at most. I bought mine from the parts counter at Ford. Its not like the o-ring that goes to your thermostat housing. it is like 1/4 inch wide (cant remember off the top of my head) and like an inch circumference. I would suggest a new coolant temperature sensor while your at it. those should come with the o-ring already (mine from autozone did)

12-13-2009, 10:51 PM	#26
wth Wannabe Elite Explorer Join Date: Mar 2009 Posts: 17 Vehicle Specs	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.

12-14-2009, 12:34 PM	#27
nickorsi Wannabe Elite Explorer Cumming,Ga 05 Mountaineer Join Date: Mar 2007 Posts: 31 Vehicle Specs	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?

12-17-2009, 02:48 AM	#28
VORTMAX_99 Wannabe Elite Explorer Gorham ME 2003 Sport Join Date: Jan 2006 Posts: 34 Vehicle Specs	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

12-17-2009, 10:55 PM	#29
clarks2001 Wannabe Elite Explorer Ashburn, Virginia 2002 Explorer Limited Join Date: Apr 2008 Posts: 203 Vehicle Specs	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.

12-20-2009, 05:50 PM	#30
VORTMAX_99 Wannabe Elite Explorer Gorham ME 2003 Sport Join Date: Jan 2006 Posts: 34 Vehicle Specs	Thanks for the info Clarks2001, George.

01-20-2010, 05:46 PM	#31
clarks2001 Wannabe Elite Explorer Ashburn, Virginia 2002 Explorer Limited Join Date: Apr 2008 Posts: 203 Vehicle Specs	Ok, so why did ford make the thermostat housing out of plastic? This isnt as bad as the last one but it really makes me mad because I just bought it on October 21, 2009 and didnt get around to installing it until December (yeah I know, I am lazy lol) and its already leaking. Pics are the first 4 images: http://s467.photobucket.com/albums/r...t=DSC00358.jpg

08-11-2010, 07:34 PM	#32
JazzyJ Wannabe Elite Explorer Nevada '02 Explorer XLS Join Date: Aug 2010 Posts: 2 Vehicle Specs	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

08-11-2010, 08:54 PM	#33
dvictor Wannabe Elite Explorer Honolulu, HI 2002 Explorer XLT 4.0L Join Date: Nov 2009 Posts: 16 Vehicle Specs (Original Poster)	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.

03-23-2011, 07:28 PM	#34
Tpayneful Wannabe Elite Explorer Ruther Glen, VA 2003 XLT 4x4 Join Date: Apr 2010 Posts: 5 Vehicle Specs	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. 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?

03-25-2011, 09:53 PM	#35
Tpayneful Wannabe Elite Explorer Ruther Glen, VA 2003 XLT 4x4 Join Date: Apr 2010 Posts: 5 Vehicle Specs	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.

06-06-2011, 03:15 PM	#38
FAMILYMAN1981 Wannabe Elite Explorer sacramento '03 xlt v6 Join Date: Jun 2011 Posts: 3 Vehicle Specs	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?

06-06-2011, 03:20 PM	#39
FAMILYMAN1981 Wannabe Elite Explorer sacramento '03 xlt v6 Join Date: Jun 2011 Posts: 3 Vehicle Specs	"EXPROBLEMS" after re reading the link u sent i know understand the procedure. I appreciate all the help.

06-06-2011, 06:33 PM	#40
Tpayneful Wannabe Elite Explorer Ruther Glen, VA 2003 XLT 4x4 Join Date: Apr 2010 Posts: 5 Vehicle Specs	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!