Fixed my coolant leak - not what I thought

[Froggy]

I had been loosing coolant for a few weeks & eliminated the hoses as a problem & I could not really see all the way up to the w/p weep hole, but I assumed that was where it was originating.

So I bought all the parts, needed a stat and serp belt anyway @ 95,000 miles.

Got it all apart (you do NOT need to pull radiator) and found the weep hole bone dry.

Turns out that the leak was one of two coolant sensors found just in back of the stat housing was loose. It's not a really good design as there is no gasket on the sensor.

If anyone knows why Ford put TWO sensors there I would love to know, I don't have a factory service manual on this vehicle.

I made one out of "Right Stuff" gasket maker and screwed it back in. I replaced the w/p anyway with a Bosch (lifetime) for 66 bucks & replaced the serp belt, stat, fresh coolant, rad cap, etc. The coolant was clear & looking into the radiator was like looking into a new one. I believe I had done one other coolant service @ about 50k miles.

The parts store (Pep Boys) had a screw up with the hoses being wrong parts (in their computer) for my 2000 xlt 4.0 sohc so I reused the same hoses, they looked good & felt good inside & out @ 95,000 miles, that's some rugged hose material.

I figure if I need to do hoses later it's no biggy as they are pretty easy to access.

Ran it up the fwy at 90 or so & back home to inspect & no leaks, good to go.

Hope this helps someone, as you "may" be able to get to that sensor w/out pulling the w/p.

Happy 4th & please vote as many idiots out of DC as you can in Nov. They are ruining the country.

 

[budwich]

don't know about the "lack of a gasket".... probably shouldn't need one IF the proper thread has been deployed (pipe thread).... but the reason for the two sensors is pretty straight forward, one is for your gages and the other is for your engine computer.

 

[Froggy]

Thanks Bud.

It's not a pipe thread type seal. The female side is a metal insert into the plastic composite housing for the stat, black plastic looks similar to the intake plastic. The male is also a metal brassy type contact surface with a raised bit that seemed to me to look like where a crush washer (say copper) would go, but there was no washer where I thought there should be one, just a flat metal to flat metal seal for coolant. The "Right Stuff" seems ok so far.

 

[Rudy602]

Which sensor was it? Driver's side or passenger side?

 

[Froggy]

Which sensor was it? Driver's side or passenger side?

The leaky one was towards the driver side. I just took a very small turn on the other sensor to tighten a bit.


Should have took a pic, sorry.

If you take a light & look from the driver side immediately behind the stat housing you can see both sensors. You don't even need to pull the beauty cover over the engine.

Wires going into both sensors, of course. Right behind (to the rear) of stat housing on my 2000 4.0 sohc.

 

[Rudy602]

I pulled both of mine and even though they looked the same from the outside, they looked very different on the threaded end. The one on the drivers side had a small black rubber o-ring that was barely visible at the top of the threads but the other didn't and the threaded end was considerably larger. I wire brushed the blue green crust off and carefully reinstalled them both with thread sealant. Sure beat changing the water pump, huh?

 

[Froggy]

Good job, I wonder if the seal/oring/gasket on mine had just "evaporated" after 95 k miles.

Nice to not smell the distinctive coolant odor anymore.

 

[xglyphicx]

oh cmon! smells like waffles . Lol JK. Ya, I am pretty sure my 4.0 ohv is about in need of a water pump replacement (193k).. I'm not losing coolant - I can just hear when the stat opens and releases the coolant, it makes an odd noise.. almost like a "tick tick pshhhh" is about the best I can describe it.. what can I say I'm not very animated.

I waited under my hood for almost an hour idling to hear where it was coming from.. and stat housing seems to be the culprit.

 

[Froggy]

oh cmon! smells like waffles . Lol JK. Ya, I am pretty sure my 4.0 ohv is about in need of a water pump replacement (193k).. I'm not losing coolant - I can just hear when the stat opens and releases the coolant, it makes an odd noise.. almost like a "tick tick pshhhh" is about the best I can describe it.. what can I say I'm not very animated.

I waited under my hood for almost an hour idling to hear where it was coming from.. and stat housing seems to be the culprit.

You have very good hearing if you can hear a stat open. I would say you are due for all the cooling system parts with those miles.

I was surprised how good my radiator held up.