Thermostat - install / symptoms / overheating (1 Viewer)

[Newps]

** 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.

 

[hankinid]

** 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.

.................snipped............

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.

..................snipped.............

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.

Newps, great writeup...I did the t'stat yesterday after fixing a leak in the water intake housing caused by not enough fipg the last time the original owner had it done. Mine is an '01, so if later models don't use the jiggle valve please ignore.

Steve

 

[Newps]

Steve:

I made the changes to the write up per your recommendations. I thought it was weird to put the jiggle valve at high noon but that was the way it came out. So that was the way I put it back in. Good know there was a reason for it being in that position. Good idea too to check the radiator after 50 miles too. I doubt there would be any drop in coolant but in case someone did not fully burp the system of any air this is a good backup.

Tare

 

[hankinid]

Steve:

I made the changes to the write up per your recommendations. I thought it was weird to put the jiggle valve at high noon but that was the way it came out. So that was the way I put it back in. Good know there was a reason for it being in that position. Good idea too to check the radiator after 50 miles too. I doubt there would be any drop in coolant but in case someone did not fully burp the system of any air this is a good backup.

Tare

I've noticed the system is an easy burper. Level in the recovery tank stays constant in the cold or hot modes after 4-6 cool-hot cycles.

I just re-checked everything for tightness and installed the airbox. Easy but messy.

Have a good Halloween.

Steve

 

[uzj100]

Thank you for the instructions. Completed today in under 30 minutes. You guys rock.

 

[Somebodyelse5]

I just want to add that steps 2-7, although they make access easier, are not really necessary. I replaced mine last night in about a half hour without removing anything but the 3 nuts on the housing and the house clamp.

 

[Brian Waag]

** 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.

Newps - Thanks for posting this thread. I'm planning to (finally) change my thermostat tomorrow. When I bought my 100 about 4 years ago, I had the coolant flushed, but didn't do the thermostat swap. Been having some weird temp issues the past 3 weeks so am starting with the t-stat in hopes that the problem is that simple (we'll see....). Briefly, here is what I'm seeing: Driving on open hwy at 65 mph, outside air temp is ~ 90 deg. F. Engine temp (using ODB2 scan guage) shows typically between 195 and 197. Go up a grade, engine temp goes up to about 211 - 213 (never used to get above 202). Start driving on a down grade, engine temp cools to about 202 - 205, but never gets back to 195-197. Stop and get gas, head back down hwy, engine temp again at 195 - 197, and then going up another grade, the scenario repeats itself. Also, when pulling over and sitting at idle, engine drops back down to 195 - 197. Installed new fan clutch about 2 years back and similar to your description of testing yours, mine responds similarly. We'll see....

 

[94SRUNNER]

Newps - Thanks for posting this thread. I'm planning to (finally) change my thermostat tomorrow. When I bought my 100 about 4 years ago, I had the coolant flushed, but didn't do the thermostat swap. Been having some weird temp issues the past 3 weeks so am starting with the t-stat in hopes that the problem is that simple (we'll see....). Briefly, here is what I'm seeing: Driving on open hwy at 65 mph, outside air temp is ~ 90 deg. F. Engine temp (using ODB2 scan guage) shows typically between 195 and 197. Go up a grade, engine temp goes up to about 211 - 213 (never used to get above 202). Start driving on a down grade, engine temp cools to about 202 - 205, but never gets back to 195-197. Stop and get gas, head back down hwy, engine temp again at 195 - 197, and then going up another grade, the scenario repeats itself. Also, when pulling over and sitting at idle, engine drops back down to 195 - 197. Installed new fan clutch about 2 years back and similar to your description of testing yours, mine responds similarly. We'll see....

Report back. Hopefully it is as simple as a thermostat! Check the heater tees while you are in there!

What brand of thermostat are you planning on going with?

 

[flintknapper]

Replace thermostat AND radiator cap. Both OEM. Then take it for a test drive...see if that helps. Fan clutch sound s like it might be OK.

 

[Leandro]

As the OP said, make sure to have 1 gallon of coolant and a big pan to catch the coolant when remove the old t-stat.
I put a rag under it thinking that may lose 1 cup of coolant (based on my experience with other cars), boy was I wrong.... I made a mess....

 

[Brian Waag]

Report back. Hopefully it is as simple as a thermostat! Check the heater tees while you are in there!

What brand of thermostat are you planning on going with?

I'm using a Toyota OEM 180 deg F thermostat. Curiously, the dude at the Toyota dealer said that they also have one rated for 170 deg F. I asked him which was standard and he said the 180. Also, I replaced the heater "T's" shortly after I bought the Cruiser. Did the same with my 80 before I sold it (miss the old girl...).

To catch the fluid, I did what Tare did, I borrowed one of those large, black, plastic containers that folks use for mixing concrete that my neighbor loaned me. I have 1 gallon of Toyota "red" coolant and a gallon of distilled agua to replace what spills into the container.

Additionally, my brother-in-law (mechanical engineer, pilot, amateur race car driver) suggested replacing the radiator cap but if I have no leaks from there (which I confirmed, the level is still just below the cap when I removed it 2 days ago), I don't see any reason to??

 

[94SRUNNER]

The radiator caps can fail over time and if they do not open and close as designed, they can cause coolant temp issues. They are pretty cheap (even the Toyota OEM units) to replace.

I'm using a Toyota OEM 180 deg F thermostat. Curiously, the dude at the Toyota dealer said that they also have one rated for 170 deg F. I asked him which was standard and he said the 180. Also, I replaced the heater "T's" shortly after I bought the Cruiser. Did the same with my 80 before I sold it (miss the old girl...).

To catch the fluid, I did what Tare did, I borrowed one of those large, black, plastic containers that folks use for mixing concrete that my neighbor loaned me. I have 1 gallon of Toyota "red" coolant and a gallon of distilled agua to replace what spills into the container.

Additionally, my brother-in-law (mechanical engineer, pilot, amateur race car driver) suggested replacing the radiator cap but if I have no leaks from there (which I confirmed, the level is still just below the cap when I removed it 2 days ago), I don't see any reason to??

 

[Brian Waag]

The radiator caps can fail over time and if they do not open and close as designed, they can cause coolant temp issues. They are pretty cheap (even the Toyota OEM units) to replace.

Yes, they are indeed cheap, so I guess it's worth it. Will run over to the local Toyota dealer later today and swap it out after I replace the t-stat. About ready to jump into it now. Will take and post pics.

 

[flintknapper]

Additionally, my brother-in-law (mechanical engineer, pilot, amateur race car driver) suggested replacing the radiator cap but if I have no leaks from there (which I confirmed, the level is still just below the cap when I removed it 2 days ago), I don't see any reason to??

It's up to you of course, but at least 3 knowledgeable people are trying to impress upon you the cheap insurance of a new OEM radiator cap. IF you are pretty certain your old one is still good...it can be kept for a spare.

The radiator cap on my 80 series was not 'leaking' either...but that wasn't the problem with it. It had stuck closed and was not allowing overflow to occur into reservoir (no expanded coolant out of the system and no cooled fluid back in either). Engine coolant temps were elevated until I replaced the cap.

 

[Brian Waag]

It's up to you of course, but at least 3 knowledgeable people are trying to impress upon you the cheap insurance of a new OEM radiator cap. IF you are pretty certain your old one is still good...it can be kept for a spare.

The radiator cap on my 80 series was not 'leaking' either...but that wasn't the problem with it. It had stuck closed and was not allowing overflow to occur into reservoir (no expanded coolant out of the system and no cooled fluid back in either). Engine coolant temps were elevated until I replaced the cap.

Yep - agree with your logic (at least 3 knowledgeable people...) so will plan to do that, today. Just finished replacing the t-stat. One correction from my prior post: The t-stat and o-ring/gasket were purchased at Napa Auto Parts and NOT Toyota (I purchased the red anti-freeze from Toyota only, memory gets kinda shaky as I get older...). I took a pic of both the Toyota OEM and Napa replacement and will post here in a bit when I finish hosing down the under-carriage that received a fresh-coating of anti-freeze.... I elected to NOT remove the plastic engine cover, air filter box, etc., as I was able to get to all 3 nuts on the t-stat housing cover. Now, back to completing the job...

 

[Brian Waag]

Hmmmm.... Ok, so here's an issue that just popped up. After following the instructions that Tare posted above regarding re-filling the radiator, leave the radiator cap off, etc., I did just that. When the engine temp reached ~ 100 deg F., the radiator fluid started over-flowing out of the top of the radiator. Shouldn't this be flowing into the fluid reservoir?? Uh-oh?

 

[94SRUNNER]

So I understand...You left the cap off while bleeding air from the system and when the coolant temp hit 100* F, it start overflowing out of the radiator?

Coolant wil only flow into the reservoir if the cap is on and function as designed. Otherwise the coolant will take the path of least resistance...in this case out of the top.

A note about the NAPA thermostat, if you look at my cooling system maintenance thread, I mention that in my experience the NAPA thermostat runs hotter that the Toyota OEM thermostat. I prefer the Toyota thermostat. Just my $0.02.

Hmmmm.... Ok, so here's an issue that just popped up. After following the instructions that Tare posted above regarding re-filling the radiator, leave the radiator cap off, etc., I did just that. When the engine temp reached ~ 100 deg F., the radiator fluid started over-flowing out of the top of the radiator. Shouldn't this be flowing into the fluid reservoir?? Uh-oh?

 

[Brian Waag]

Hmmmm.... Ok, so here's an issue that just popped up. After following the instructions that Tare posted above regarding re-filling the radiator, leave the radiator cap off, etc., I did just that. When the engine temp reached ~ 100 deg F., the radiator fluid started over-flowing out of the top of the radiator. Shouldn't this be flowing into the fluid reservoir?? Uh-oh?

So, here are some pics I took while swapping the thermostat: 1) hose removed from housing, 2) t-stat housing covered removed, 3) old (on left) vs. new ( on right). As mentioned prior, I was able to remove the hose and t-stat housing cover with removing any other engine parts. However, I did remove the cheap-o OEM skid plates underneath to try to better control the coolant pouring out of the t-stat housing. Also, the nuts for the t-stat housing are 12mm. Tare mentioned in his write-up that you needed a 10mm. Perhaps earlier 100's had a different size?? Mine is an 06. Last, I buttoned everything up, drive the Cruiser around the block a few times and up a few hills, temp got up to 198 deg F. So, appears that I still have an issue, and may be tied to the fact that when I was going thru the radiator fill procedure, coolant began overflowing out of the radiator cap opening when the car was on and temps exceeded 100 deg. F. So, I put the cap on and drove around a bit. I'll wait until the engine cools off then remove the cap again and see if the level is low, however any other suggestions as to what the issue might be would be greatl

So I understand...You left the cap off while bleeding air from the system and when the coolant temp hit 100* F, it start overflowing out of the radiator?

Coolant wil only flow into the reservoir if the cap is on and function as designed. Otherwise the coolant will take the path of least resistance...in this case out of the top.

A note about the NAPA thermostat, if you look at my cooling system maintenance thread, I mention that in my experience the NAPA thermostat runs hotter that the Toyota OEM thermostat. I prefer the Toyota thermostat. Just my $0.02.

Pete - Just, I left the cap off. After I sent my prior comment I realized that the cap needs to be on for the system to function properly (dump fluid in the reservoir, or pull from the reservoir). And yes, it started flowing out of the radiator.

I understand regarding the Toyota OEM vs. Napa, however unfortunately missed that comment you made in your thread about the Napa running hotter... Anyhow, just went out and pulled the cap off, the fluid level was very close to the top. Also looked in the reservoir and it was about 3 inches below the fill line so I added coolant up to the line. Will go run it again and see what temps look like.

 

[94SRUNNER]

@Brian Waag did you have the front end slight elevated while you bleed the system? Also, while bleeding make sure you run the HVAC on full heat to help cycle the coolant through the whole system and bleed any air out of the heater core for both the front and rear systems.

I haven’t run into the same issue as you while bleeding the system. Are you letting the engine just idle while it warms and cycles the coolant?

 

[Brian Waag]

Yea, my driveway has a little uphill slant on it and had assumed that would be good enough. I did also have the heater/AC on full heat ("hot") and kept the fan on low per Tare's write-up.

Just got back from doing some errands, found the fluid reservoir just a little over the fill line. Scan gauge temps are running the same, and just saw 200 deg F at idle at a traffic light. So..... no change as of yet, however I haven't yet driven on a highway/freeway to see temps at 65 mph or higher. Also, just in case, I ran by Toyota and grabbed another t-stat and gasket ($30).