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Thermostat Housing - Help Please (One car)

NeuroResid

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City, State
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Year, Model & Trim Level
1999 Ford Explorer XLT
Installed new hoses and thermostat (upper and lower) on my 1999 XLT SOHC 4.0 Explorer. Everything looked clean and well fitted until I turned the engine on. Almost immediately, coolant rushed out between the seal where the upper portion (smaller square piece with three individual bolts) met with the lower housing.

Did I miss a gasket or something? The kit I bought included the thermostat, upper and lower gasket, and sensors, but did I neglect to buy a thermostat gasket, or a gasket for the seal between the upper and lower portion?

Any assistance is appreciated. This has been a huge pain, especially without the proper tools - although I've purchased them along the way deep into the night.


New Parts Installed:

Upper radiator hose (longer piece)
Upper radiator hose (shorter piece between metal sleeve and thermostat)
Bypass hose
Unknown hose between thermostat and plastic tube
Thermostat Housing (upper and lower)
Thermostat Sensors

New, but not installed yet:

Lower radiator hose
 



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Lazzman

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I did this job about 3 months back but I had to replace the lower thermostat housing because the plastic eventually seperates and causes a leak, in you case though it sounds like you might have left out the rubber O ring gasket that sits between the two housings.

Did you remember putting this round O ring gasket in? there is a channel in the housing that it drops into. This would definately cause the leak your talking about
 






drdoom

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Lazzman is right o ring.
 






swshawaii

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Possibly over tightened? Both lower and upper housing torque spec is only 89 inch/lbs. (7-8 ft/lbs.)
 






joecrna

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Rushing out= O-ring gasket

Dripping, even fast= cracked housing. Overtightened bolts or Leak at sensors if the were not preinstalled in new housing.

Just most common causes.
 






NeuroResid

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Good News:


1. Installed the o-ring around the thermostat; no more leak (as of yet, anyways).

Bad News:

1. The temperature gauge inside the cabin no longer works. It didn't work prior to the new cooling parts listed above, but it worked briefly before the thermostat housing leaked initially after replacement.

Perhaps the coolant grounded the wire?

2. The "Check Gauge" light is on (red light).

3. After running the car for a while, I turned the heat on and felt the upper radiator hose (which was pretty hot!), but I'm not getting any heat in the cabin. Well, a little, but only when I step on the gas.

4. Unless I'm crazy, I hear a rotational clicking noise coming from underneath the center console. Heater core? When I removed the old thermostat lower housing, a little piece of degraded plastic fell into the bypass hose. Perhaps it cycled into the heater core tubing?


Anyway, any advice is appreciated.

Lastly, unless I'm wrong, is it reasonable to think the thermostat sensor(s) grounded briefly after the initial coolant leak (because I forgot the o-ring), then subsequently failed to transmit the signal. Because the signal is improperly grounded, the thermostat is not opening?

I'm not into this coolant stuff. . .
 






joecrna

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Thermostat is a simple mecchanical unit. Bi metal spring opens and closes it.
 






J_C

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If coolant grounded the coolant temp sensor then the gauge would read hotter than normal. Possibly the contacts are corroded or the sensor just failed.

You can use a multimeter to check the sensor. With engine cold it should (usually, I don't know specifics for an Explorer) read a few thousand ohms. With the engine up to temperature it should drop to a few hundred ohms. The engine need not be running but of course the key must be in the on position.

You can also use the multimeter on the connector to it. On one wire you should have a voltage relative to chassis ground. AFAIK it should read close to 5V if not more.

It might only need unplugged, rinsed out, dried, and plugged back in.
 






rb142

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It sounds like you may have an air pocket trapped in there. Make sure you have all the air out. Check the wiring to the sensor -- you may have a bad connection or a broken wire.

I wonder whether that little piece of plastic is jamming something up. Generally not a good idea to drop debris in there and not get it back out.

You replaced all that other stuff. Did you replace the thermostat itself? Are you sure it is the right one for this vehicle (right temp range, etc.)? Sounds like it isn't opening up for some reason (or not opening much).
 






NeuroResid

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It sounds like you may have an air pocket trapped in there. Make sure you have all the air out. Check the wiring to the sensor -- you may have a bad connection or a broken wire.

I wonder whether that little piece of plastic is jamming something up. Generally not a good idea to drop debris in there and not get it back out.

You replaced all that other stuff. Did you replace the thermostat itself? Are you sure it is the right one for this vehicle (right temp range, etc.)? Sounds like it isn't opening up for some reason (or not opening much).

I tried to get the piece out, but unfortunately had little luck. Perhaps it is an air pocket. I'll double check that tonight. Yes, I did change the thermostat and thermostat housing. I went with a oem replica, set at 195.
 






Lazzman

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Couple things I would check are coolant level to make sure it has enough, not enough coolant will make the heater run cool, air bubbles, make sure to run you heater on high for 30 minutes or more and lastly your thermostat, they do fail quite a bit.

Also those sensors fail all of the time, I put in a brand new coolant temp sensor when I did my repair and it was Doa and needed to be replaced.
 






NeuroResid

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Everything works now! Sorta. . . Flushed it one more time with new coolant, turned the heat on but the fan off, started it up and guess what? No problems! And, the heat is hotter than I've ever felt it before.

BUT, the dash temp. gauge is still acting odd. I unplugged both the grey plug and red/orange plug (clips). Each have two wires. The orange one is responsible for the dash gauge issue.

While the Explorer is on, the gauge will not drop back to cold when I unplug the orange clip, but when the car is off, it drops to cold. Start the Explorer? Shoots back up. Hmm. . . Ground? Faulty wire?
 






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