How to: Replace a thermostat on a 1996 4.0L OHV V6. | Ford Explorer Forums - Serious Explorations

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How to: Replace a thermostat on a 1996 4.0L OHV V6.

Charlie

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Joined
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City, State
Wisconsin
Year, Model & Trim Level
2000 Limited
Well, after replacing my thermostat I decided to do a write up on it. If you are needing to replace your thermostat, I highly recommend doing it yourself. It is easy to do, and very cheap.

Note: This is for the 4.0 OHV, not SOHC

First, a general disclaimer: I am not a Ford engineer, and do not work for Ford. Anything that you do, you do at your own risk.

Now to start. It should take about an hour to complete this, but giving yourself plenty of time is the first step. The tools I used are very common, and can be found just about anywhere.

Before you start, drain all of your coolant out of the car. This will make your life a lot easier down the road.

IMG_0789.jpg

Tools used:
3/8" Drive ratchet
3/8" 2" drive extender
3/8" to 1/4" drive reducer
1/4" drive ratchet
10mm socket
8mm socket
Flathead screwdriver (not pictured)

Parts needed: Thermostat
New coolant

Now, where is the thermostat located?
IMG_0794.jpg

IMG_0793.jpg

It is on the end of the hose going to both the engine block and the radiator. It is where the hose bolts onto the block.

First off: The intake needs to go. Take off the latch for the filter, unplug the 2 plugs in the intake, and pull the vacuum line out. Now, unscrew the hose clamp with the flathead screwdriver, and remove intake.
IMG_0791.jpg

Now there is that throttle cable cover there. That needs to be removed. Take you 8mm socket, and remove the 2 bolts holding that on.

After that is removed, remove the 3 bolts holding the hose on. These use the 10mm socket. It will take some experimentation with the different extenders/ratchets I have listed, but it can be done with just that. When you are loosening up the bolts and removing the hose, be prepared for coolant to leak from there. Have something underneath the front of the truck to catch it, Either an oil change pan or just some old towels.
Once removed, you will see this:
IMG_0785.jpg

IMG_0787.jpg

Please note that the thermostat shown in this picture is actually the new one, yours will not look that nice. It will also be wedged in there solid, and take some wiggling to remove.

When you place in the new one, be sure it is aligned the same way, and rotated the same way as the last one.

Now, put the hose back, and tighten in the 3 bolts. Then re-attach the throttle cable cover. Now put the intake back on. Be sure to re-attach both sensor plugs, and also the vacuum line.
IMG_0798.jpg

Now, refill the coolant and burp the system.

You have now successfully changed your thermostat. Take it for a drive, then check for any leaks.

IMG_0800.jpg

This is the old thermostat. Note how the gasket around it is worn and chipping.
Just remember, replacing your thermostat is easy to do yourself, and a lot cheaper too. Just take your time, and everything should go fine! If I have left anything out that you think should be added, be sure to add it or let me know!
 



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Good write-up. Note that it's for an OHV, not an SOHC motor.

-Joe
 












Thanks, just added it on.


Maybe a moderator could add OHV into the title?

Yeah, I just looked to see if there was some way to edit it, but couldn't.

Moderator help would be appreciated here. :D
 


















A 10mm gear ratchet socket (hollow socket for removing long studs) fit perfectly to remove the bolt behind the idler. You can probably use something else but that very short socket got it off in one shot. If you have this set its worth a try.
Also, be sure the replacement stat is OEM or has a bleed hole. This helps purge the air when you refill coolant. Also, if your temp gauge is flaky a thermostat and the one wire sender will fix the issue.
 






im sorry i know this is an old thread but what does it mean to "burp" the system?:D Also sorry for the probably dumb questions, but how do you drain the coolant? im not really an engine guy haha.
 












im sorry i know this is an old thread but what does it mean to "burp" the system?:D Also sorry for the probably dumb questions, but how do you drain the coolant? im not really an engine guy haha.

Here is the official procedure from the Ford manual. If you have 4.0L OHV engine be sure to follow this procedure to get out all the air. It is also in your owners manual!

WARNING: NEVER REMOVE THE RADIATOR CAP UNDER ANY CONDITIONS WHILE THE ENGINE IS OPERATING. FAILURE TO FOLLOW THIS INSTRUCTION COULD RESULT IN DAMAGE TO THE COOLING SYSTEM OR ENGINE AND/OR PERSONAL INJURY. USE EXTREME CARE WHEN REMOVING THE RADIATOR CAP FROM A HOT RADIATOR. IF POSSIBLE, WAIT UNTIL ENGINE HAS COOLED, THEN WRAP A THICK CLOTH AROUND THE RADIATOR CAP AND TURN IT SLOWLY TO THE FIRST STOP. STEP BACK WHILE THE PRESSURE IS RELEASED FROM THE COOLING SYSTEM. WHEN YOU ARE SURE ALL THE PRESSURE HAS BEEN RELEASED, PRESS DOWN ON THE RADIATOR CAP (STILL USING A CLOTH), TURN AND REMOVE IT.

Draining

Shut off engine (6007) and allow to cool.

Remove the radiator cap (8100). Refer to above warning.

Attach a 9.5mm (3/8-inch) inside diameter hose on the radiator draincock (8115) to minimize loss of coolant when draining. (look under your radiator - passenger side)

Open radiator draincock and permit coolant to drain into a clean container. (spray a bit of PB on it, then unscrew it)

Remove drain plug on cylinder block (6010) to allow coolant to drain from engine, if necessary. (not needed)

Dispose of old coolant properly. Promptly clean up any spilled coolant.


At this point you may want to flush the system, there are many ways. You can use a kit.

I like disconnecting the heater hose at the heater control valve, and inserting a push connect garden fitting into both hoses with the clamp(one is a drain or can be blocked off and another part open (e.g. rad cap)). Make sure the hose isn't on full blast(1/4-1/2 is fine since the heater core is fragile). You can flush a variety of ways (heater core, block, radiator) depending on the hose configuration.


Filling

WARNING: USE CAUTION WHEN ADDING COOLANT MIXTURE TO RADIATOR TO AVOID HOT COOLANT OR STEAM BLOW OUT FROM THE RADIATOR.

NOTE: Use the following steps to remove air from the cooling system and to make sure fill is complete. (VERY IMPORTANT FOR THE 4.0L)



NOTE: When filling a crossflow radiator (8005), allow time for the coolant to flow through the radiator tubes to fill both tanks.


Close radiator draincock and install cylinder block drain plug.

Fill the cooling system with a 50/50 ethylene glycol and water mixture. Allow several minutes for trapped air to escape (bubble out) and for coolant mixture to flow through the radiator.

Install radiator cap to pressure relief position by installing radiator cap to fully installed position and then backing off to first stop. This will allow any air to escape, and minimize spillage.


Slide heater temperature and mode selection levers to maximum heat position.

Start engine and run at fast idle (approximately 2000 rpm) for three to four minutes. Shut engine off.

With engine off, wrap radiator cap with a thick cloth, carefully remove radiator cap and add coolant to bring coolant level up to filler neck seat.

Replace radiator cap to fully installed position. Then, back off to first stop. Operate engine at fast idle until the upper radiator hose (8260) is warm (water thermostat (8575) opens). To check radiator, shut engine off, wrap radiator cap with thick cloth and carefully remove radiator cap. Add coolant if necessary. Replace radiator cap to fully installed position.

Open the small cap on the top of the radiator coolant recovery reservoir. The large cap is for the windshield washer reservoir. NEVER put coolant mixture in windshield washer bottle.

Using a suitable suction gun, remove all coolant from radiator coolant recovery reservoir.

Add 1 liter (1.1 quarts) of 50/50 mixture of ethylene glycol and water to the radiator coolant recovery reservoir. Close the small cap. (or fill between the hot and cold marks - suction gun is optional)


Also, check the level after a few trips. The OHV may need a bit extra coolant because of air issues.
 






i had a problem with my engine overheating. i followed your guide step by step on replacing the thermostat and it, well, again -- i had a problem...
thanks for the info charlie. :thumbsup:
 






Charlie you did clean up the gasket surface and used a new gasket right?
 






Thermostat has a built in gasket, so there is no gasket needed.
 






Great Write Up! Just purchased a Stant SuperStat 195 degree Thermostat p/n 59369 for $7.99, the kid at auto store said to get a Rubber Water Outlet Gasket as well. Anyone have any recommendations on other brands i.e. Hypertech 180 degree t-stat, Beck Arnley etc. The Stant is made in USA with a lifetime warr. They also sold a "Motorcraft" t-stat for $21.99 but I find it hard to believe there would be much difference for the added money. Plan on installing it in the next couple of weeks when it gets a little warmer. Anyone want to share their 2cents would be appreciated.
Thanks, Rick
 






Don't use the rubber gasket IMHO. I'd use a regular ol' paper gasket with some RTV. It was good enough to never leak from the factory, right? Rubber gaskets never seem to hold up for me. Paper with the proper gasket sealant has never let me down.

-Joe
 






Great write up. It made me finally get off my arse and replace my thermostat.

"Before you start, drain all of your coolant out of the car. This will make your life a lot easier down the road." Pay attention to that part! I didn't and and watched a good portion of my coolant pour out when I removed the old thermostat. duh!
 






I just changed mine , I had no idea anything was wrong until I got a scantool and realized it was operating 20 c less than it should be. I changed the thermostant and the problem was fixed and the heat starting working much better
 



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Seems like a lot of explorers have thermostats that get stuck open, just from reading on here......and I'm the newest one...lol
 






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