2UZ-FE Normal Operating Temperature (3 Viewers)

[Beau]

Well I went for a quick drive and it hasn't changed anything. If anything, I am now cruising in town higher and see 203 sitting still. I'm begining to wonder if the temp sensor is reading right. The one for outside was reading 64 today when Florida was in the upper 80's. Maybe it got went from rain? I'll try zapping the thermostat with a temp gun to see what it reads. Either way, I'm gonna be looking at the temps the entire trip.

To make matters worse, after giving the radiators a wash, she TPS sensor or something was playing up because I'd have no throttle whatever, it wouldn't move. It would also linger after getting off the throttle. I hope that's just water getting in somewhere. Started it up few times and it seems ok now but damn, I'm a little worried about my trip tomorrow.

 

[94SRUNNER]

@2001LC what are your thoughts on running a 0.9 bar radiator cap versus the factory 1.1 bar radiator cap?

@Beau are you sure you got all the air out of the system after installing the new thermostat?

 

[Beau]

@94SRUNNER Here's what I did. Also bare in mind, I did my best to conserve as much coolant as possible and kept the hose as upright as possible during the change. Once buttoned up, I brimmed the radiator with coolant. Expansion tank didn't loose any so none was added. I started the truck up and let it idle for couple minutes with heaters on max, low fan, until coolant started slowly rising and trickling out from the radiator. This was under only about 2-3 minutes of idling at this point. I put rad cap on and let it idle for an additional 5 minutes, temp was reading 180. Switched it off.

Let it cool for few hours and opened the rad, it was low a little and took about a cup more of coolant. Rad cap back on and out for a good half hour drive which is when I am getting these hot temps.

What am I doing wrong here? Should I just leave the rad cap off from cold for 10+ minutes and let it essentially burp coolant and possible air out from the rad?

 

[94SRUNNER]

@94SRUNNER Here's what I did. Also bare in mind, I did my best to conserve as much coolant as possible and kept the hose as upright as possible during the change. Once buttoned up, I brimmed the radiator with coolant. Expansion tank didn't loose any so none was added. I started the truck up and let it idle for couple minutes with heaters on max, low fan, until coolant started slowly rising and trickling out from the radiator. This was under only about 2-3 minutes of idling at this point. I put rad cap on and let it idle for an additional 5 minutes, temp was reading 180. Switched it off.

Let it cool for few hours and opened the rad, it was low a little and took about a cup more of coolant. Rad cap back on and out for a good half hour drive which is when I am getting these hot temps.

What am I doing wrong here? Should I just leave the rad cap off from cold for 10+ minutes and let it essentially burp coolant and possible air out from the rad?

When I perform this procedure I allow it to idle with the radiator cap off until the the engine is up to full operating temperature. Usually 15-20 minutes at idle speed.

Is your thermostat oriented in the correct manor? Jiggle valve at ~12 o’clock.

 

[Beau]

@94SRUNNER

When you let it idle did coolant run over? As it gets up to temp, it's going to naturally expand and thus loose coolant which would normally go into the expansion tank? Yes jiggle valve is upwards, 12 o'clock.

 

[94SRUNNER]

Yes. I typically allow it run and loose coolant because I eventually burp out air that is trapped in the system.

 

[Eyedaho]

@2001LC what are your thoughts on running a 0.9 bar radiator cap versus the factory 1.1 bar radiator cap?

Based on my limited understanding, running a lower pressure radiator cap will lower the boiling point of your coolant, which is not a good thing. I can't think of why that would be advantageous unless you're experiencing component failure/leakage due to pressure.

 

[Beau]

Guess I'll report back in the AM. I leave 4pm for my trip after work.

 

[silver02accord]

@94SRUNNER Here's what I did. Also bare in mind, I did my best to conserve as much coolant as possible and kept the hose as upright as possible during the change. Once buttoned up, I brimmed the radiator with coolant. Expansion tank didn't loose any so none was added. I started the truck up and let it idle for couple minutes with heaters on max, low fan, until coolant started slowly rising and trickling out from the radiator. This was under only about 2-3 minutes of idling at this point. I put rad cap on and let it idle for an additional 5 minutes, temp was reading 180. Switched it off.

Let it cool for few hours and opened the rad, it was low a little and took about a cup more of coolant. Rad cap back on and out for a good half hour drive which is when I am getting these hot temps.

What am I doing wrong here? Should I just leave the rad cap off from cold for 10+ minutes and let it essentially burp coolant and possible air out from the rad?

I let bleed for

Guess I'll report back in the AM. I leave 4pm for my trip after work.

I ran for 20 min in driveway, high heat and revered to 2k per fsm. mostly full radiator but it didn't bubble over I squeezed lines too. I was getting to 197 before tstat change, now 185 is highest I have seen on 2 trips today. Some coolant got sucked up from reservoir tank when I checked back a few hours after my first test drive.

 

[jerryb]

The spec in the book is 11.xx something psi for a flush, and a new cap is mandated on radiator replacement. So right there you're lower than .9bar
Just fyi.

edit, it doesn't mandate a new cap. Just that minimum opening of relief valve on a used cap is 11.4 psig
New cap opening spec is 13.4 - 17.8 psig

 

[Beau]

Thought the new cap was 1.1 Bar which is 16 PSI. 0.9 Bar is around 13 which falls just short of your range.

@94SRUNNER

Bled the system as you did this morning. It definitely had air in the system still, mostly in the return hose back to the rad. I could tell by a cooler spot on it. Anyway, after a good 25 minutes idling, a couple 2k revving moments, lots of hose squeezing, the max temp I see at idle was 197 and it normally knocks back down to 195 within a couple seconds. Driving in traffic, AC on, 84 degrees outside, I saw between 199-203. Driving at 50mph yielding 193 which is a improvement.

 

[silver02accord]

BTW this was my old tstat and new one, def. don't think old was opening fully. Maybe hard to tell from pic but old is "shorter"

 

[Ambledog]

I fill it up, put the cap on, run engine. Then squeeze the upper radiator hose to move air out until I hear it stop moving air, or it gets too hot to handle. Check overflow, fill to about middle between the LOW and FULL lines. I run the heaters front and rear on high. Drive it around. I keep about a gallon of coolant pre-mixed ready to go in the rig for about a month, keep a very close eye on coolant level. A lot to times as engine cools down it will pull from the overflow since some air got burped. Keep overflow filled at least to the LOW line. When I turn it off and engine at full temp, the overflow will be higher as coolant expands, and once it cools down, coolant drops about 1/4 to 1/2 inch. Once all that stabilizes and I'm not seeing any big drops in the overflow for a week or two, I fill the coolant overflow so when completely cold the level is about 1/2 inch below FULL line. And then when it is fully up to temp, it stays right at the FULL line. Very easy to check from then on if more air is getting out or not. And then my temps are stable as well. With air in there it can be hard to know if the temp is very accurate.

 

[94SRUNNER]

Thought the new cap was 1.1 Bar which is 16 PSI. 0.9 Bar is around 13 which falls just short of your range.

@94SRUNNER

Bled the system as you did this morning. It definitely has air in the system still, mostly in the return hose back to the rad. I could tell by a cooler spot on it. Anyway, after a good 25 minutes idling, a couple 2k revving moments, lots of hose squeezing, the max temp I see at idle was 197 and it normally knocks back down to 195 within a couple seconds. Driving in traffic, AC on, 84 degrees outside, I saw between 199-203. Driving at 50mph yielding 193 which is a improvement.

Glad you were able to see improvement.

BTW this was my old tstat and new one, def. don't think old was opening fully. Maybe hard to tell from pic but old is "shorter"View attachment 2396466

Are they both OEM?

 

[silver02accord]

Glad you were able to see improvement.

Are they both OEM?

The replacement 100 percent was oem and I'm pretty sure the old one I removed was the original oem tstat as well. Had lexus maintenance history dealer maintained and it was never replaced as best I could tell-unless they jus did it with the new radiator 2 yeara/15k ago. They had the same markings on top 28c I think it was and some other etches.

 

[silver02accord]

The correct OEM temp for the thermostat to open on a 100 series land cruiser is 195F. Once the engine coolant reaches the operating temperature, usually around 195 degrees, the valve in the thermostat will open and close as you drive in order to maintain a coolant temperature typically between 195 to 225 degrees Fahrenheit. If you are running an engine that runs under 195F at operating temperature then you are not operating the engine at temp that it was design to run. Many people switch the 195F to a 185F thermostat which is not the one intended for the 100 series land cruiser.

Where were you able to find this information on operating temperature I would be interested to read it. Thanks for the explanation

 

[jerryb]

179.6

 

[TLCOVERLAND]

If you call any Toyota dealership and talk to a mechanic or parts manager, they can look up and tell you the correct thermostat temp you need for your TLC and explain the correct temp your engine should run at. Every engine is design to run at a specific temperatures from the factory.

 

[jerryb]

Dear lord.

 

[TLCOVERLAND]

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