Right front engine water leak

[okxlt2003]

My 2003 4.0 started leaking water, what appeared to be about half way down the right front of the engine. (behind the alternator bracket) At first I thought it was the water pump, since I haven't changed one on it and it has 194,000 on it. So I swapped out a new water pump. It still leaking!!! More investigation I found out the thermostat lower water outlet was the culprit. Replaced the water outlet, thermostat, thermostat cap, all the seals and the bypass hose. Everything is fine now No leaks.

 

[D Hook]

Thanks for posting that. Good outcome!

 

[Huskerbob]

I have the same problem. I added about 1.5 gallons to the reservoir to bring it to cold full level. After driving today I noticed a little antifreeze smell and now it is dripping a little on the garage floor. The leak is coming from that same area you describe but I can't see the actrual source. Would I do the pieces except the water pump first? Then if that doesn't solve it replace the water pump? Is that the correct sequence? Thanks.

 

[D Hook]

That's how I would do it. Cheapest parts first, if you can't identify the exact source.

Let us know how you come out.

 

[swshawaii]

The lower thermostat housing is a very common failure on the 4.0L SOHC.
Use a mirror and a flashlight to check. If not, rent coolant system pressure
test kit from most auto parts stores with a fully refundable deposit. Call first.
Use this as a reference, and double check part numbers for your vehicle. GL

http://bengrosser.com/howto/fordthermostat/

 

[okxlt2003]

I replaced my water pump cause, my expl had so many miles and I had never replaced the waterpump. Thought that to be the most probable cause. The "rubber band" style seal/gasket that ford uses under the thermostat housing to intake is pretty flimsy. I can understand why it would fail over time. The one thing I did learn is use water at first for your leak check. It doesn't take much to drain the system and antifreeze is getting expensive. Hope this helps a little.

 

[okxlt2003]

Almost forgot, you should replace the bypass hose if you change out that lower seal/gasket.

 

[Huskerbob]

Thanks for all the help. As soon as I get it cooled down and get the parts I will take care of it. It's not a bad leak but it sure is annoying. I guess at 118,000 miles it's probably time. Thanks again. I'll post the results.

 

[Huskerbob]

I found a repair kit on ebay for $131 which includes upper and lower housings, thermostat and all the 'O' rings and gaskets. The seller is autopartsdirect2 you. I think I will give that a try if inspection shows it's not just a loose hose or fitting. Does anyone have any experience with non dealer parts like this?

 

[swshawaii]

The build quality and fit seems better with the Motorcraft replacements.
Only parts needed are the (RH148) single sensor lower housing, (DY1004)
ECT sensor, and two 0-ring gasket seals. Thermostat and water pump
bypass hose are optional. Check Amazon or RockAuto for pricing. GL

 

[Huskerbob]

Thanks for the heads up man. I need to diagnose first to see what all I need to repair. Very slow drip after warmed up so it's not a huge priority today. Rear suspension first then water leak.

 

[Huskerbob]

thermostat leak identified

That's how I would do it. Cheapest parts first, if you can't identify the exact source.

Let us know how you come out.

Okay, I spent the weekend looking for the source of the leak. Pulled the alternator and the alternator mounting bracket to get a good view of things. From what I could tell it was t-stat housing. Took it to the radiator shop today and they comfirmed that the housing is leaking. Probably the 'O' ring. Their recommendation was to replace the housing, flush the system etc. and all for only $550.00. I politely declined their assistance. I will pick up a new 'O' ring at the parts store today and get it changed. I will post on the results.

 

[swshawaii]

As mentioned, it's the LOWER THERMOSTAT HOUSING known to split at the middle seams. Replacing just the lower "rubber band" o-ring will usually not stop your leak. Not a difficult repair, just very confined and time consuming. Make sure, it's a PITA and not a job you want to do twice. Also, a 90* bent plier will save lot's of aggravation removing and replacing the clamps for the short water pump bypass hose. Done.

 

[Huskerbob]

As mentioned, it's the LOWER THERMOSTAT HOUSING known to split at the middle seams. Replacing just the lower "rubber band" o-ring will usually not stop your leak. Not a difficult repair, just very confined and time consuming. Make sure, it's a PITA and not a job you want to do twice. Also, a 90* bent plier will save lot's of aggravation removing and replacing the clamps for the short water pump bypass hose. Done.

I found a Motorcraft new housing on ebay for $39. I think that might be the way to go. What say you?

 

[swshawaii]

The build quality and fit seems better with the Motorcraft replacements.
Only parts needed are the (RH148) single sensor lower housing, (DY1004)
ECT sensor, and two 0-ring gasket seals. Thermostat and water pump
bypass hose are optional. Check Amazon or RockAuto for pricing. GL

Shows both the flex and non flex fuel '03 Explorer uses the TWO sensor RH144.
Open your hood and check. You will also need to order the SW6146 gauge sender,
the old ECT sensor and sender are too small for the new housing. Stay posted.

 

[Huskerbob]

thermostat housing leak

Shows both the flex and non flex fuel '03 Explorer uses the TWO sensor RH144.
Open your hood and check. You will also need to order the SW6146 gauge sender,
the old ECT sensor and sender are too small for the new housing. Stay posted.

Aloha, yep mine is leaking from the seam on the back for sure. It is a one sensor housing. I looked at that part number SW6146 and it doesn't show for my vehicle. I will double check that. All my hoses and clamps look like new so I'm guessing this work has been done prior to my purchase of the truck. I'll report the results of my repair. Mahalo.

 

[swshawaii]

Bob- Then you need the single RH148 housing, DY1004 ECT sensor, and the two 0-rings.
Follow this link with pictures for a walk through. BTW, good "Hawaiian" speak you have.

http://bengrosser.com/howto/fordthermostat/

 

[Huskerbob]

thermostat housing and sensor

Bob- Then you need the single RH148 housing, DY1004 ECT sensor, and the two 0-rings.
Follow this link with pictures for a walk through. BTW, good "Hawaiian" speak you have.

http://bengrosser.com/howto/fordthermostat/

Yep, I have the RH148 on order and the local Ford dealer has the DY1004 on hand just in case. I suspicion that I may have one already as I think this is a replacement housing on the vehicle. As soon as I learn Hawaiian for "I'll have a beer" I'll be set.

 

[Huskerbob]

Thermostat housing leak

Bob- Then you need the single RH148 housing, DY1004 ECT sensor, and the two 0-rings.
Follow this link with pictures for a walk through. BTW, good "Hawaiian" speak you have.

http://bengrosser.com/howto/fordthermostat/

Okay, I got the new housing installed. Easy. 3 bolts for the housing and 3 for the thermostat cover. The old sensor fit but it was sloppy so I went to Orielly Auto parts and picked up one for $15. Lost the little spring clip so I went to the Ford dealer and they have them for ONLY $6 OMG!

It very obvious that the seam on the back side of the housing was split and the source of the leak. Got it all back together and everything is dry.

Thanks for all the help.