Thermostat coolant leak

[Allstar54]

I have an '02 XLT and it developed a coolant leak today. The check engin light came on while on my way home, but the temp never raised. When I looked at it after there was coolant all over and when I squeeze the main hose, it sprays out between the upper and lower thermostat housing. I have been searching the forum and that lead to a few questions. Is it weird that the temp sensor stayed normal, but the check engine light came on? Should I assume it is a warped lower housing or could it be just a O ring and a new one with a bunch of thermostat gasket maker with solve the problem? There are 2 sensirs on the lower housing and one is unplugged and I can't find a line that would plug in there. Normal or is that the cause of the reading not changing? The lower housing is not leaking from the bottom and I am confused on if a warped housing causes the leak on the bottom, top, or both. Sorry, a lot of questions, but I planned my first road trip in the Explorer this weekend and of course that is when this all happens. Thanks in advance.

 

[Allstar54]

Here is the sensor that is not connected. Where might the connection be? Does it come from the same harness as the sensor next to it? The leak is from the upper housing below the+ symbol in the pic, where it meets the lower housing.

 

[swshawaii]

Very likely the lower housing is leaking at the "welded" seams, very common.
I believe the later SOHC only had the gray ECT sensor, other is a blank sender.
Use your VIN and go to Fordparts.com to confirm your correct part numbers.
Replace the two port housing with the single RH148 and DY1004 sensor.
One less sensor to buy and chance of leaking. Also consider changing the
short bypass hose, it's around $10 and much easier to change while apart. GL

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

 

[stoogefan]

I have an 02 XLT and it only has one temp sensor. Maybe yours was replaced previously with one from a different year. That would explain why there is nothing to connect it to.

 

[Allstar54]

It does look replaced. It has blue RTV on all the bolts. I'm worried it is not reading temp right. When the engine light came on but the temp didn't ride, I kept driving home only to find out it was a mistake.

 

[Allstar54]

Update. It was the lower housing. It was all torn up around the outer lip (not bad, but enough to leak). Replaced the lower and upper housing, the O rings and the sensor and all is well. Thanks!

 

[Allstar54]

Follow up on this. I have developed a small second leak. It appears to be from the temp sensor. When I installed the new T-stat upper and lower housing and sensor, I noticed it was VERY lose, but did not appear to leak, so I let it go. Well about 3 months later and it is leaking again. Coolant is pooled on the top of the housing and I am suspecting the sensor because it is so lose. Did they give me the wrong part or is it not supposed to be as tight as my original, which had no give and was difficult to pull out. This one wiggles back and forth and is only held in by the O ring. I have seen some posts about putting gasket maker on the sensor and it will seal up, but I would rather it fit correctly. I can't find my paperwork from the original purchase so I don't don't know the part number they sold me. I am thinking I will just try the gasket maker unless someone can confirm that the sensor fit should be much tighter and I just need to go get the correct part.

 

[swshawaii]

I assume you used the RH144 two sensor housing as a replacement.
You will either need to buy another sensor to seal the leaky port, or
find a 9mm I.D.x 2.5 or 3mm thick Viton-o-ring. Had the same dilemma
and attempted to use RTV sealant that seeped two months later.
Did you see my post above regarding the single hole RH148 housing?

 

[Allstar54]

Yeah, I saw your post and decided it sounded like a good idea to buy the single sensor port housing. I'm not sure what part they gave me, but fordparts.com says the PN is RH-93. They gave the the sensor from the same part diagram, so I can't see how it wouldn't fit unless they grabbed the wrong one. Maybe I can get the O-ring and try that? The part number listed for the sensor was DY-882.

 

[swshawaii]

Interesting, RockAuto shows the RH148 as the correct housing.
The sensor is a compression fit and should have no movement
once you install the horseshoe retainer clip. Either the housing
or the sensor are not the correct part. Call the parts seller. GL

 

[Allstar54]

Hmmm. You know what I didn't notice the retainer clip in the parts diagram and I am pretty sure I don't have one. I'll stop by the parts place and make sure I get the right part/clip. Thanks for talking me through it.

 

[swshawaii]

Hmmm. You know what I didn't notice the retainer clip in the parts diagram and I am pretty sure I don't have one. I'll stop by the parts place and make sure I get the right part/clip. Thanks for talking me through it.

Surprised you didn't have a mini geyser under your hood!
May be a dealer only special order item. Careful, they're tiny.

 

[Allstar54]

Yeah, it was holding good enough, but didn't take much to pull it out. Hopefully that clip will seal it up tight. Thanks.

 

[swshawaii]

Sorry, I didn't read this in post #7:

This one wiggles back and forth and is only held in by the O ring.

 

[Allstar54]

Installed the retainer today. Not the problem. I think it's leaking from between the upper and lower thermostat housing. I'm going to see if Ford will replace the parts they gave me.

 

[swshawaii]

The Motorcraft RH93 lower t-stat housing was replaced by the RH148.
I suspect they gave you the wrong ECT sensor. When installing, it should
"snap in" with no movement without the retainer. There is a known leaking
problem with mixing housings and sensors. Is the "rubber band" seal OK?

http://www.fordpartsgiant.com/parts/ford-housing-thermostat_rh-93.html

 

[Allstar54]

I'm sick of dealing with the leak, so I bought new upper/lower housing, sensor and gaskets. I think you are right about Ford giving me the wrong part. I can't find my parts list or invoice and they lost the order in their system. Hopefully it will solve the problem. Just irritating that I am buying the same parts as I did a few months ago. Thanks for talking me through it.