Thermostat

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Remove the heat shield that covers it. 3 or 4 bolts. I had to remove that in order to get a tool on the top nut.
Remove the three nuts on the side of the water pump.
When you move the housing, you'll lose quite a bit of coolant, if you haven't already drained the system. It's best to do this when you are flushing the cooling system.
Move the housing aside.
Use a screw driver through the little "cage" on the old thermostat to gently pop it out.
Install the new gasket on the new thermostat.
Install the new thermostat with the jiggle valve between 11 and 1 o'clock position.
Put it all back together. The nuts should be torqued to 15ft-lbs, which is snug but not super tight.
Replace the coolant you lost.

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Make sure it's only OEM parts. I had an aftermarket t-stat installed from the PO that was slow to come up to operating temp and had pretty wild swings in temps per the Scangauge. New genuine Toyota t-stat comes up to normal operating temps quicker, and holds normal temps a lot more steady.
 
OEM Tstat

Make sure it's only OEM parts. I had an aftermarket t-stat installed from the PO that was slow to come up to operating temp and had pretty wild swings in temps per the Scangauge. New genuine Toyota t-stat comes up to normal operating temps quicker, and holds normal temps a lot more steady.

X2 on that. No comparison between OEM and aftermarket stuff.
 
Make sure it's only OEM parts. I had an aftermarket t-stat installed from the PO that was slow to come up to operating temp and had pretty wild swings in temps per the Scangauge. New genuine Toyota t-stat comes up to normal operating temps quicker, and holds normal temps a lot more steady.

I had the same experience...
 
Remove the heat shield that covers it. 3 or 4 bolts. I had to remove that in order to get a tool on the top nut.

I was able to get to all the fasteners without removing the heat shield. One is a little tricky but you should be able to get it. Careful if you decide to remove the heat shield as it could lead to broken fasteners.

If you plan to reuse the coolant, you can drain the radiator from a petcock on the drivers side. I use a small length of hose that will attach to the drain hole and drain the coolant into a bucket. This is really a good time to flush the system.
 
I was able to get to all the fasteners without removing the heat shield. One is a little tricky but you should be able to get it. Careful if you decide to remove the heat shield as it could lead to broken fasteners.

I agree completely. I did get a wrench on the tricky one without removing the shield, but there was no room to actually spin the nut. Sockets were too fat to get under the shield, etc.

But when I turned the bolts for the shield, I got the impression they would easily break. None did though. Removing the shield should be a last resort. Maybe it would be smart to replace all the bolts holding the shields on before they get too much more rusty and baked in place.
 
Are people referring to the exhaust manifold heat shield on a 1FZFE when replacing the T-stat??
 
IIRC I used a socket with an extension for the bottom nut and the top front nut and a box wrench on the top rear nut.
DSC00773.JPG
 
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IIRC I used a socket with a short extension for the bottom nut and the top front nut and a box wrench on the top rear nut.

Great picture. That reminds me why I had the problem. It's because I couldn't find that wrench. I was stuck with sockets, or the open-end wrench. Sockets didn't fit in the gap with the ratchet, and the open end didn't give a good angle. So the shield had to go.

Having the right tools (or at least being able to find them) makes all the difference.

I'm going to go buy another 12mm wrench on the way home, and also some 12pt sockets.
 

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