2004 explorer thermostat 3 bolts holds it on? will the plastic housing leak? should i use distilled water?

There is a gasket on the base of the housing, the housing you speak off has the sensor and a heater hose and bolts to top of the intake and also hold the thermostant, this housing does contain a rubber molded gaske, i have replaced a few of these, heres the problem i have run into a couple where the plastic was eaten away in the area that holds the gasket in place. if you remove it you will see a groove that the gasket sits inside of, if the groove is broken then replace the housing but if its good then all you need is the gasket, you will need to ask for thermostat housing gasket to engine intake, this gets confusing to a parts person as they may think you are asking for the thermostat gasket, also in the rear bottom of the housing theres a hose connected to the housing make sure thats not your leak, the hose may also be leaking. good day

1. Diconnect negative battery cable.

2. If the vehicle has an automate transaxle, remove the exhaust manifold before proceeding with the removal and installation of the thermostat.
3. Drain the cooling system. 4. Take out the bolts that hold the water pump feed pipe to the thermostat housing. 5. Lift out the thermostat-housing-to-water-pump feed pipe. 6. Pull out the thermostat. 7. Set the new thermostat in position. 8. Connect the thermostat housing-to-water-pump feed pipe.
9. Set the bolts in place that holds the thermostat-housing-to-water-pump feed pipe. Torque the bolts to 89 inch pounds. 10. Install the exhaust manifold. 11. Refill the cooling system to the proper level with a 50 / 50 mixture of distilled water / DEX Cool approved coolant. 12. Start the engine and check for leaks. 13. Make the necessary adjustments to coolant levels to assure optimum engine performance.

Please see my tip at http://www.fixya.com/cars/r5929960-s_thermostat .

Specific instructions for your car are as follows. Let me know if you get stuck or have more questions.

Removal & Installation

4.2L Engine

1. Remove the necessary coolant from the radiator.
2. Remove the alternator, as outlined in the Engine Electrical Section.
3. Loosen the outlet hose clamp at the thermostat housing. Remove the outlet hose from the thermostat housing.
4. Remove the thermostat housing bolts.
5. Remove the thermostat housing from the engine block.
6. Clean all of the surfaces of the thermostat housing.
7. Clean the sealing surface of the engine block.
   

To install:

1. Install the thermostat housing to the engine block.
2. Install the thermostat housing bolts and tighten to 89 inch lbs. (10 Nm).
3. Lubricate the inner diameter of the radiator hose with engine coolant.
4. Install the outlet hose to the thermostat housing. Secure the hose with the clamp.
5. Install the alternator.
6. Fill the cooling system with specified coolant and concentration.
7. Inspect all sealing surfaces for leaks after starting the engine.

5.3L Engine
NOTE The thermostat is not serviceable separately. The water pump inlet and thermostat must be replaced as an assembly.

1. Drain the cooling system to a level below the thermostat.
2. Remove the radiator outlet hose.
3. Remove the water pump inlet bolts.
4. Remove the water pump inlet and thermostat from the water pump.

To install:

1. Install the thermostat and thermostat housing to the water pump.
2. Install the thermostat housing bolts. Tighten the bolts to 11 ft. lbs. (15 Nm).
3. Install the radiator outlet hose.
4. Properly fill the engine cooling system and check for leaks.

its likely the plastic housing leaking , gone bad
a replacement housing and thermostat are in order.

Have you checked the thermostat and/or the coolant level? SAFETY: DO NOT DO ANY OF THIS WHILE THE ENGINE IS HOT!

To check the coolant level, open the hood and look for a plastic cap with the thermometer symbol on it. (Do not confuse this with the windshield washer reservior, which has a windshield symbol on it). With the engine cold, look through the translucent plastic and compare the coolant level to the raised markings on the reservior. Fill as needed with a 50/50 mixture of coolant and distilled water.

To find the thermostat housing, follow the radiator hoses back to where they enter the engine block. You should see a hemispherical housing held on with two bolts. That is the thermostat housing. Remove the bolts and the thermostat, being careful to note how everything was positioned. Replace the housing and refill any lost coolant. Realize that we are still in the diagnostic phase. Run the engine until you are satisfied that it is not over-heating. It will not hurt the engine to run without a thermostat, but your heater will not work. To install a new thermostat, remove the housing and clean off all the old gasket and install the new one that comes with a new thermostat (if you do not clean off all the old gasket before installing the new one it will probably leak). Put the new thermostat in place in the same position as the old one, replace the housing and refill any lost coolant.

remove radiator house from thermostat housing inlet... then remove two bolts that hold the housing on... remove thermostat from housing... replace thermostat with new one... make sure housing does not have any of the old gasket left on it, then replace gasket... ensure you use high temprature rtv.... then put the bolts back in and then put the hose back on... hope this helps

It Depends on which engine you have, this is how it goes for both. I use a little RTV with a new ring as well.

THERMOSTAT REPLACEMENT (4.2L ENGINE)
Removal Procedure
1. Remove the necessary coolant from the radiator.
2. Remove the generator.
3. Loosen the outlet hose clamp at the thermostat housing. Remove the outlet hose from the thermostat housing.
4. Remove the thermostat housing bolts.
5. Remove the thermostat housing from the engine block.
6. Clean all of the surfaces of the thermostat housing.
7. Clean the sealing surface of the engine block.
Installation Procedure
1. Install the thermostat housing to the engine block.
2. Install the thermostat housing bolts.
Tighten: Tighten the bolts to 10 N.m (89 lb in).
3. Lubricate the inner diameter of the radiator hose with engine coolant.
4. Install the outlet hose to the thermostat housing. Secure the hose with the clamp.
5. Install the generator.
6. Fill the cooling system with specified coolant and concentration. Follow the correct cooling systen bleed procedure for your engine.
7. Inspect all sealing surfaces for leaks after starting the engine.
THERMOSTAT REPLACEMENT (5.3L ENGINE)
1. Drain Radiator and remove the radiator outlet hose.
2. Remove the water pump inlet bolts.
3. Remove the water pump inlet and thermostat from the water pump.
Installation Procedure
IMPORTANT: The thermostat is not serviceable separately. The water pump inlet and thermostat must be replaced as an assembly.
1. Install the thermostat and thermostat housing to the water pump.
2. Install the thermostat housing bolts.15 N.m
3. Install the radiator outlet hose.
4. Fill the cooling system with specified coolant and concentration. Follow the correct cooling systen bleed procedure for your engine.
5. Inspect all sealing surfaces for leaks after starting the engine.

1. drain coolant
2. remove engine cover
3. remove the 2 bolts from water hose connection (upper rad hose connecting to)
4. remove o-ring and thermostat
5. repeat in reverse order

Explorer Thermostat LocationHere is advice for finding the thermostat:

• Follow the upper radiator hose from the radiator to the engine and there is a housing that houses the thermostat. Take it off and when you reinstall the thermostsat, make sure the spring goes toward the engine.

• The thermostat is located on the motor block under the three bolt flang that the top rediator hose connects to. Remove the three 10MM bolts and the thermostat can be removed for replacement.

How to Change an Explorer Thermostat

• 1. Remove the air cleaner air duct from the throttle body and air cleaner.
• 2. Follow the upper radiator hose to the engine to locate the thermostat housing. The housing is located at the front of the intake manifold.
• 3. Loosen the hose clamp, then detach the hose from the fitting. This can be difficult. If it's stuck, grasp with a pair of adjustable pliers and twist to break the seal. Then pull it off.
• 4. Remove the bolts and detach the housing cover. Be prepared some coolant may leak out as the gasket seal is broken. Remove the thermostat.
• 5. Install the new o-ring onto the thermostat (no gasket is needed) and install the thermostat into the intake manifold with the spring side pointing toward the engine.
• 6. Make sure the air release valve is in the up 12 o'clock position. Install housing cover and bolts. Reattach the hose fitting and tighten the hose clamp. Fill the cooling system with a 50/50 mix of coolant and water, and burp the system.

please rate as fxed if this helps.

Thermostat, Water, 3.0L Aerostar and Ranger Removal

1. Drain cooling system.

1. Remove upper radiator hose (8260) from water outlet connection.

1. Remove two retaining bolts.

1. Remove water outlet connection and water thermostat (8575) as an assembly.

1. Discard gasket. Clean sealing surfaces with gasket scraper. Gouges in aluminum could form leak paths. Use care when scraping thermostat housing-to-gasket mating surfaces.

Installation

1. Make sure sealing surfaces are totally free of gasket material.

1. Install water thermostat into thermostat housing as illustrated.

1. Position gasket onto thermostat housing using bolts as holding devices. Install water thermostat and tighten bolts to 20-30 Nm (14-21 lb-ft).

1. Install upper radiator hose . Tighten clamp securely.

1. Fill and bleed cooling system with proper amount and mixture.

1. Start engine (6007) and check for coolant leaks.