Thermostat - install / symptoms / overheating (1 Viewer)

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Hey gang - Still having issues and could really use some additional suggestions... Here's the situation this morning:
1) I drained about a cup of coolant out of the radiator bottom drain valve due to the problem I had yesterday (coolant started to overflow with radiator cap off, per Tare's procedure above). 2) Engine warmed up to about 186 degrees, coolant started to overflow AGAIN out of the top of the radiator.

It appears that the new t-stat never opened because the level never dropped? Also, when I was replacing the fluid yesterday after replacing the t-stat, ~ 10 cups came out of the housing into my bucket (there was additional that absorbed into the rag I used to plug off the hose coming out of the t-stat housing), so I actually put a little bit less back in then what came out.

Suggestions???
 
It is strange that you keep experiencing the bubble over. I have bleed my cooling system a lot as of late and I have never had this happen, with the exception of once when I was reeving the engine, which caused a surge of coolant to blow out.

Are you allowing the engine to idle throughout the warm up and bleeding process?

You may want to go to one of your local auto parts stores and rent a coolant vacuum pump and see if that helps. I wish I was closer so I could assist you with the process.
 
Yea, I know, very strange. Particularly when the system had less coolant in it now, then when I swapped the t-stat. And yes, I'm letting the engine idle the entire time. Even though my driveway has an uphill slope, I put the Cruiser up on blocks to elevate the front end even further to assist with burping the system. I just found out that a neighbor around the corner is a Toyota mechanic (does side jobs out of his house), so am planning to drag him over and see if he has any additional suggestions.

Thanks for keeping track of this issue btw, and offering suggestions, it's much appreciated.
 
Just wanted to add part numbers to this thread

Can't seem to find part numbers for clamps

Also, not sure why the standard procedure for most is to pull your hose and let coolant spill everywhere.
>> Drain your coolant from the radiator and avoid the mess.

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Newps said:
** Original thread here **

So I decided to re-post this install under it's own thread. That way someone searching "thermostat", "overheating", etc. on Mud will find it.

Well it’s been hot here in SoCal the last few days. We hit 86 on Saturday and Sunday. Took the family out for lunch had the front and rear AC on high and the check engine light came on. I figured no biggie; it came on before when I needed to clean the throttle body. After lunch it was still on, drove home (3 miles) and just when I was about to turn it off I noticed the engine temp, pegged in the red, . Popped the hood and could hear the coolant boiling in the radiator. Since the drive was so short I’m pretty sure it did not overheat and the radiator did not boil over. Poked around on mud while it cooled down to see what could be the problem. Narrowed it down to two possibilities, thermostat or fan clutch. Went out and tried to turn the fan blade, it rotated about 1/8 of a turn and came to a stop, most likely ok. Gripped and squeezed both of the upper radiator hoses: the one just past the thermostat was easy to squeeze and felt empty of coolant. The other hose was hard to squeeze and felt like it was full of coolant. This lent me to believe a stuck thermostat was the source of my over heating problem. The thermostat is an easy and cheap first option anyway. A quick call to the local Toyota steelership and a 10% TLCA discount (always good to ask) and I was back in 15 minutes with $30 bucks in parts in hand.

Now I searched on Mud and no one had done a write up on how to change out a thermostat. I guess because it is just a basic item to replace no one thought it necessary to write it up. Well kids that’s about change.

Items needed-
1. New Toyota thermostat + a New Toyota thermostat gasket.
2. Large plastic catch container. (see below).
3. About a gallon of 50% mix of Toyota (red or green) coolant and distilled water. ** Check to see what color coolant your engine has. **
4. 10 mm socket with an 8 inch extension.
5. 10 mm open ended wrench.
6. Channel locks

Step 1: Place a large catch basin below the front of your engine. I’ve found these great plastic containers at Home Depot. They are black about 2 ft wide by 3 ft long and 12 inches high. They are used for mixing cement. I use this same container for my oil changes too. It’s the perfect size and catches just about everything that can drip out of your engine bay.

Step 2: Remove plastic engine cover.(unclip the hose on the driver side)

Step 3: Remove the top half of your airbox, (four metal clips).

Step 4: Separate the electrical connection on Mass Air Flow sensor (plastic clip).

Step 5: Remove the three or four tubes that attaches to the large plastic piece that is in between the air filter and throttle body.

Step 6: Remove the two bolts that secure the large plastic piece that is in between the air filter and throttle body.

Step 7: Remove the throttle body inlet tube and remove the entire large airbox to throttle body assembly.

Step 8: Locate the thermostat housing, passenger side tube to lower radiator. Use a pair of channel locks, squeeze and slide the hose clamp down the tube. You will want to slide this clamp far enough down the tube so that with your hand you can grab and hold the tube to wiggle it off the thermostat housing. Get ready for coolant to start pouring out when you remove this tube. I lost about 2 to 3 quarts while I was changing out my thermostat. It all spilled down the front of my engine and went into the large plastic container. I grabbed a couple of paper towels and stuffed’em into the hose end to keep the flow to a minimum.

Step 8: Remove the three nuts that secure the thermostat housing. (More coolant to exit the engine block and radiator tube when this is removed)

Step 9: Remove the thermostat, if yours is stuck in place use the channel locks to remove the thermostat.

Step 10: Install the new thermostat gasket on the thermostat and install into the thermostat housing. Install the thermostat so the "jiggle valve", as the FSM describes it, is located at the 11 to 1 o'clock position in the housing. It allows a little circulation until the thermostat opens.

Step 11: Repeat the previous steps in reverse order. One item to remember is to tighten the thermostat nuts evenly to make sure you get a proper seal. No not over tighten these nuts, just snug them down with the same amount force you felt when you backed them off.

Step 12: After everything is all buttoned up and back to the way you found it. Take a hose and wash down everything that the coolant could have dripped on. If you own any pets keep them away while you are washing the residual coolant away. They have a tendency to like the taste/smell of coolant.

Step 13: Open up your radiator cap and set it to the side. Place a funnel over the radiator and fill it. Keeping the radiator cap off, start your truck and move the interior heat setting to high but keep the fan to off or low depending on your vehicle’s controls. Monitor the coolant level in your radiator it will take a little while for your engine to heat up. Once it does the thermostat will open and the coolant lever in the radiator will drop. Top it off once it does and monitor for a few more minutes to make sure all the air bubbles are out of your coolant system. Turn off the engine and install your radiator cap. Then top off your coolant over flow bottle (if it needs it) and you are done.
** Check coolant level after 50 miles or so and top-off the recovery tank if needed. **

I hope this write up helps anyone else who may have some questions about this process. I learned not ignore my check engine light. I was lucky and only drove a short distance this could have been much worse.
Click to expand...
I would also add drilling a 1/8 hole on two opposite side of the thermostat to allow any trapped air to escape.

I've done that on every thermostat I've installed in Las Vegas. If you drive a ford or chevy you can get the thermostat with the holes already drilled.
 
Michaelinlv said:
I would also add drilling a 1/8 hole on two opposite side of the thermostat to allow any trapped air to escape.

I've done that on every thermostat I've installed in Las Vegas. If you drive a ford or chevy you can get the thermostat with the holes already drilled.
Click to expand...

That is what the jiggle valve is for, pretty sure every thermostat has this.
 
Brian Waag said:
Yea, I know, very strange. Particularly when the system had less coolant in it now, then when I swapped the t-stat. And yes, I'm letting the engine idle the entire time. Even though my driveway has an uphill slope, I put the Cruiser up on blocks to elevate the front end even further to assist with burping the system. I just found out that a neighbor around the corner is a Toyota mechanic (does side jobs out of his house), so am planning to drag him over and see if he has any additional suggestions.

Thanks for keeping track of this issue btw, and offering suggestions, it's much appreciated.
Click to expand...

@Brian Waag did you ever get any resolution?
 
I can't get the thermostat to go back into the housing. I pulled out thr thermostat that was in there but can't it back in (or the new one I bought) Any tips?

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edit
 
Last edited:
Update:

Got the thermostat installed(lost fluid) when removing tubes. I positioned jiggle valve at 12 oclock and had marked with a sharpie where to put it exactly as previously installed. I added 2 qts of 50/50 Toyota red coolant mixed with distilled water. I left radiator cap open, turned heat on high and let truck sit and get warmed up. After a bit I held idle at rpm between 2k and 2.5k per fsm. The temperature got up to ~208 F. I let run a little longer and it cooled down a bit to lower 200s. This seems unusual to me.

I shut off car and squeezed the 2 thick hoses one at the top DS and one that goes from the radiator to the thermostat. The hose at the DS was easily squeezed and did not feel full. When I squeezed the hose going from rad to thermostat I could hear the fluid slush around/move in the radiator(cap was still open) I also tried this with engine running.

I put cap on to take for a test drive. Just driving down the street with heater off the temp started climbing and got up to 231, I turned around at the end of the street and parked in the drvieway. When I opened the engine bay I squeezed the upper DS radiator hose coming from engine and it was hard, it felt "full" and it did not feel so before(see above)

Obviously something is not right-I am guessing the thermostat is not opening up? I was very cautious about tightening the bolts evenly and installed a new gasket and everything.

Also it did not pull any coolant from the reservoir. I had it marked. The level in the radiator does not appear to have dropped either(when I checked it prior to it getting to 231)

Any suggestions?

Additoinal update:

I went out to the truck and squeezed the line going to the thermostat from radiator, coolant temp ~160 deg. I could hear the coolant move in the radiator and tube as well as I metallic sound clink sound coming from what I assume is the thermostat.

Also I installed part # 90916-03100, I see there is also a part number 90916-03138.

I am going to reinstall the old thermostat tomorrow and report back. I am wondering if it is wrong part or thermostat which I purchased is defective.

Should I also look at replacing the engine control temperature sensor?
 
Last edited:
silver02accord said:
Update:

Got the thermostat installed(lost fluid) when removing tubes. I positioned jiggle valve at 12 oclock and had marked with a sharpie where to put it exactly as previously installed. I added 2 qts of 50/50 Toyota red coolant mixed with distilled water. I left radiator cap open, turned heat on high and let truck sit and get warmed up. After a bit I held idle at rpm between 2k and 2.5k per fsm. The temperature got up to ~208 F. I let run a little longer and it cooled down a bit to lower 200s. This seems unusual to me.

I shut off car and squeezed the 2 thick hoses one at the top DS and one that goes from the radiator to the thermostat. The hose at the DS was easily squeezed and did not feel full. When I squeezed the hose going from rad to thermostat I could hear the fluid slush around/move in the radiator(cap was still open) I also tried this with engine running.

I put cap on to take for a test drive. Just driving down the street with heater off the temp started climbing and got up to 231, I turned around at the end of the street and parked in the drvieway. When I opened the engine bay I squeezed the upper DS radiator hose coming from engine and it was hard, it felt "full" and it did not feel so before(see above)

Obviously something is not right-I am guessing the thermostat is not opening up? I was very cautious about tightening the bolts evenly and installed a new gasket and everything.

Also it did not pull any coolant from the reservoir. I had it marked. The level in the radiator does not appear to have dropped either(when I checked it prior to it getting to 231)

Any suggestions?
Click to expand...

Did you install the thermostat in the orientation you had in the picture? That is backwards.

Once you have it back together correctly, you need to run the the engine with the radiator cap off, the heaters (front and rear) on full heat, and allow the engine to slowly come up to speed. You will want to add coolant or distilled water as the level begins to drop. Once the level appears to have stabilized, make sure the reservoir is at least 1/2 to 2/3s full, install the radiator cap and go for a drive, keeping the heat on full blast. Then park it, and allow it to fully cool off over night. The next morning, check the level in the reservoir it should be around half way. If it is lower, that means the cooling system has pulled coolant back in. Then pull the radiator cap and inspect the level. It should be up in the neck of the radiator opening.
 
94SRUNNER said:
Did you install the thermostat in the orientation you had in the picture? That is backwards.

Once you have it back together correctly, you need to run the the engine with the radiator cap off, the heaters (front and rear) on full heat, and allow the engine to slowly come up to speed. You will want to add coolant or distilled water as the level begins to drop. Once the level appears to have stabilized, make sure the reservoir is at least 1/2 to 2/3s full, install the radiator cap and go for a drive, keeping the heat on full blast. Then park it, and allow it to fully cool off over night. The next morning, check the level in the reservoir it should be around half way. If it is lower, that means the cooling system has pulled coolant back in. Then pull the radiator cap and inspect the level. It should be up in the neck of the radiator opening.
Click to expand...
yes I installed it that way.......................F****. thank you glad I took a picture....
 
silver02accord said:
yes I installed it that way.......................F****. thank you glad I took a picture....
Click to expand...
Also I’m sure you figured it out, but the t-stat “fits” in the block side of the housing.
 
Getting ready to do this myself. It's the last piece of my coolant system to get dialed in. Only thing keeping me from doing it is that I want to do the entire thermostat housing assembly, which requires using FIPG. But I have all the parts, including the o-ring so I should just do it.

I'll be following this though to see how it goes when you install the thermostat the right way ;)
 
shtbrwn86 said:
Getting ready to do this myself. It's the last piece of my coolant system to get dialed in. Only thing keeping me from doing it is that I want to do the entire thermostat housing assembly, which requires using FIPG. But I have all the parts, including the o-ring so I should just do it.

I'll be following this though to see how it goes when you install the thermostat the right way ;)
Click to expand...
From another thread, but everything is working great when you install the new thermostat correctly. I believe the old one was stuck/not oepning all the way:

I installed the thermostat, properly this time, and things are working great. I let idle for 20 min or so with heat on high and reved up to 2k to 2.5k to get engine temp up. Truck would not get above ~176 while sitting in driveway, ambient temp is 66-68 deg. outside. I took for test drive with heat on high and a/c on high. With heat on high I got up to a high of 185 and with a/c on high got to 186.2F. Happy with the results. I was previously running 191-197F, so I think my thermostat was defintely the culprit. I have a rad cap on order and a clutch fan assembly but may just skip the clutch fan. Thanks for help @94SRUNNER
 
Anyone have issues with the thermostat housing leaking?

I did replaced mine (actually TB, water pump, idlers, tensioner , etc.) about two weeks back. Drove it for over 50 miles no issues. Then yesterday, wife goes to the store, comes back and its leaking at the housing.

I'm guessing I may have unevenly tightened the 3 screws but seems odd considering I used a torque wrench. Anyone else have this issue?
 
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