2UZ-FE Normal Operating Temperature (4 Viewers)

[iddibhai]

More data points for late model cars, in extreme heat:

06 LX, stock (no lift/tires/bumpers/racks), 209k, tb/wp/hoses/mr T pink coolant done about 10k ago. Factory radiator, and fan clutch (it was deemed to be in great shape at tb/wp service). Going up the grade on interstate 15 between Baker and Las Vegas, last week. Afternoon sun, baking out and indicated 113F on the Baker thermometer, and 113F on car's outside air temp display. Maintained 70mph all the way up the grade with AC blasting. Peak coolant temp on OBD reader never got past 94C (201F). Usually runs around 91, going up a degree or two when idling on a hot day, or climbing long grades. Tells me there's plenty of thermal capacity in the system.

 

[silver02accord]

More data points for late model cars, in extreme heat:

06 LX, stock (no lift/tires/bumpers/racks), 209k, tb/wp/hoses/mr T pink coolant done about 10k ago. Factory radiator, and fan clutch (it was deemed to be in great shape at tb/wp service). Going up the grade on interstate 15 between Baker and Las Vegas, last week. Afternoon sun, baking out and indicated 113F on the Baker thermometer, and 113F on car's outside air temp display. Maintained 70mph all the way up the grade with AC blasting. Peak coolant temp on OBD reader never got past 94C (201F). Usually runs around 91, going up a degree or two when idling on a hot day, or climbing long grades. Tells me there's plenty of thermal capacity in the system.

Well this seems to be similar to what I am seeing -I had less extreme conditions but hit ~93. and it sounds like our cars are similar mileage and maintenance condition. I do not think my radiator cap is OEM, it doesn't have any Japanese characters on it like the oem ones I am seeing. Just waiting for the cap to come in to start there. Will prob just replace fan clutch anyway.

 

[geanes]

My 98 LX has 250k on it. Replaced the OEM radiator with a CSF back in April. Put in new hoses, thermostat, cap and filled with Toyota Red (diluted 50/50 with distilled water per FSM). Both my Fan Bracket and Fan Clutch were replaced when I did the TB/WP job last year. I did nothing "special" to the fan clutch in terms of a fluid exchange. I do a pan drain/fill on the transmission every 5k with my oil change. Under "normal" scenarios here in Central Texas (90 degrees or less and not towing), I run consistently between 188-190 on the engine and 158-165 on transmission. With temps above 100 degrees, I see 191-193 on the engine and 160-170 on the transmission. If towing in 100 degree temps (1400lb trailer), I see 191 when engine is under no strain to as high as 198 if under load (climbing a hill). Transmission temps can be 158 (coasting, OD off) to as high as 190 (steep hill under load, locked in 3rd). The main thing I'm looking for is how quick the system "recovers". In all cases, my temps fall rapidly once "load" is reduced. Can take as little as 30 seconds for the temps to drop to "normal" once load on the engine is reduced. Going up a LONG hill in West Texas a few weeks ago (107 degrees), my engine climbed to 198 and held for the duration of the climb. The transmission climbed to 196 for the duration of the climb). Upon clearing the top and running on level ground, everything fell to normal in less than 1 minute. Engine temp dropped to 190 in like 20 seconds and the transmission dropped to 158 in about 45 seconds. Those behaviors tell me my engine is operating normally and simply getting "hot" when I'm putting a heavier than normal load on the motor. My rig is 7700lbs loaded for overland (6900lb in daily trim), plus the 1400lb trailer.

 

[silver02accord]

My 98 LX has 250k on it. Replaced the OEM radiator with a CSF back in April. Put in new hoses, thermostat, cap and filled with Toyota Red (diluted 50/50 with distilled water per FSM). Both my Fan Bracket and Fan Clutch were replaced when I did the TB/WP job last year. I did nothing "special" to the fan clutch in terms of a fluid exchange. I do a pan drain/fill on the transmission every 5k with my oil change. Under "normal" scenarios here in Central Texas (90 degrees or less and not towing), I run consistently between 188-190 on the engine and 158-165 on transmission. With temps above 100 degrees, I see 191-193 on the engine and 160-170 on the transmission. If towing in 100 degree temps (1400lb trailer), I see 191 when engine is under no strain to as high as 198 if under load (climbing a hill). Transmission temps can be 158 (coasting, OD off) to as high as 190 (steep hill under load, locked in 3rd). The main thing I'm looking for is how quick the system "recovers". In all cases, my temps fall rapidly once "load" is reduced. Can take as little as 30 seconds for the temps to drop to "normal" once load on the engine is reduced. Going up a LONG hill in West Texas a few weeks ago (107 degrees), my engine climbed to 198 and held for the duration of the climb. The transmission climbed to 196 for the duration of the climb). Upon clearing the top and running on level ground, everything fell to normal in less than 1 minute. Engine temp dropped to 190 in like 20 seconds and the transmission dropped to 158 in about 45 seconds. Those behaviors tell me my engine is operating normally and simply getting "hot" when I'm putting a heavier than normal load on the motor. My rig is 7700lbs loaded for overland (6900lb in daily trim), plus the 1400lb trailer.

Thanks for the detailed information. How are you measuring trans temp, car soft, techstream bluetooth OBDII? I have a icarsoft but as best I can tell it does not measure a/t temperature-it says it does but the a/t and engine temp are the same(always) on my reader.

 

[iddibhai]

A/T fluid temp can ramp up very quickly as @geanes mentioned. Unlocked torque converter = quick ramp up, lock, quick ramp down. Some screenshots from last week's Baker grade I referenced above. First photo is 5th gear unlocked, second photo is 4th gear locked. Within the same minute time frame.

 

[silver02accord]

I replaced my thermostat and now the engine is overheating. I posted in another thermostat thread here. I believe my thermostat is opening up because when I squeeze the coolant inlet to the engine I hear the fluid move as well as the thermostat make a noise. It is at ~160 deg. right now. I'll see if it makes a noise in the morning when its cold.

 

[94SRUNNER]

I replaced my thermostat and now the engine is overheating. I posted in another thermostat thread here. I believe my thermostat is opening up because when I squeeze the coolant inlet to the engine I hear the fluid move as well as the thermostat make a noise. It is at ~160 deg. right now. I'll see if it makes a noise in the morning when its cold.

See my reply in the other thread, but it sounds like you have air in the system at the very least.

 

[JunkCrzr89]

Yep, many miss the fact, that a good wook radiator cap is so important. If stuck it can not only caused leaks. It can blow the radiator top and or heater tee's or any weak spot. Weak cap and we've other issues. All radiator manufacture recommend new cap and thermostat at time of radiator replacement.

I agree. I installed a new radiator when I did TB/WP job, but reused the old rad cap. A couple of days later I popped the hood to check coolant level and saw the brand new Toyota upper rad hose collapsed. Pulled the overflow res hose to check for blockage but it was clean. So popped the rad cap off and heard the air vacuum release immediately and upper rad hose pop back to form. Picked up a new rad cap from dealer the next day and haven’t had a problem since. Old rad cap simply stopped functioning.

 

[Beau]

Hope someone can help me out here, I didn't want to start another operating temp thread. However, here's my problem. Running in the evening last night at 80 degrees weather outside, humid florida, doing 75mph, torque app is showing 205, peaking at 210 when I accelerated hard getting on the highway up to around 80. This is pretty empty so has me worried.

Then I realized someone say in this thread check your radiator cap. Well mine is relatively new but not OEM. And it has 0.9 bar on it. A quick search indicated the stock one is 1.1 Bar. Could this difference in the system lead to running slightly hotter?

 

[94SRUNNER]

Hope someone can help me out here, I didn't want to start another operating temp thread. However, here's my problem. Running in the evening last night at 80 degrees weather outside, humid florida, doing 75mph, torque app is showing 205, peaking at 210 when I accelerated hard getting on the highway up to around 80. This is pretty empty so has me worried.

Then I realized someone say in this thread check your radiator cap. Well mine is relatively new but not OEM. And it has 0.9 bar on it. A quick search indicated the stock one is 1.1 Bar. Could this difference in the system lead to running slightly hotter?

The radiator cap could be the cause of your temp issues. I would suggest picking up the correct OEM radiator cap (16401-50210).

What is the status of your cooling system?

 

[Beau]

What is the status of your cooling system?

Radiator less than 3/4 years old, not a OEM one though and missing foam on edges. Brand new fan clutch and coolant flushed not too long ago. Around town, temps are 185-190. From what I've read it seems all a higher pressure cap does is marginally increase your boiling point. If that's the case the highter bar cap may not make a temperature difference.

All things point to the thermostat. I leave for a 3 day trip tomorrow though and generally don't like changing parts last minute so I'll probably just monitor temps during the trip and change it out when I get back.

 

[Beau]

Ok, I'm gonna bite the bullet, head to my toyota dealer, get the thermostat and change this sucker out before heading out for my trip tomorrow. I'll report back next week and let y'all know what happens with my temps. Wish me luck. Price wise they want $34 for the stat, not bad, but $10 for the gasket.

 

[shtbrwn86]

Ok, I'm gonna bite the bullet, head to my toyota dealer, get the thermostat and change this sucker out before heading out for my trip tomorrow. I'll report back next week and let y'all know what happens with my temps. Wish me luck. Price wise they want $34 for the stat, not bad, but $10 for the gasket.

Good luck! I agree about not wanting to change things out right before a trip. But it's a pretty straight forward install.

 

[94SRUNNER]

Ok, I'm gonna bite the bullet, head to my toyota dealer, get the thermostat and change this sucker out before heading out for my trip tomorrow. I'll report back next week and let y'all know what happens with my temps. Wish me luck. Price wise they want $34 for the stat, not bad, but $10 for the gasket.

Good move. Its a straightforward install, just make sure you go through the proper procedure for removing all the air from the system once the repair is complete.

 

[Beau]

Yeah, my experience is these trucks and most Toyota's are pretty easy to bleed air from the system. My BMW and 350z on the other hand were a little more of a pain.

 

[silver02accord]

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

 

[geanes]

Thanks for the detailed information. How are you measuring trans temp, car soft, techstream bluetooth OBDII? I have a icarsoft but as best I can tell it does not measure a/t temperature-it says it does but the a/t and engine temp are the same(always) on my reader.

Scangauge mounted on steering column. You have to program the X-Code to get the transmission temps. I monitor Engine Temp, Intake Temp, Voltage and Transmission Temp.

 

[Beau]

Well went to toyota on my lunch break and got it installed shortly after as well. Let it idle for 5 minutes, but will take it for a drive this evening to circulate it properly. I was able to catch about 50% of the coolant with a jug underneath and used it back.

Old one didn't look old, but I did notice the inner rubber looked a bit perished. OEM one so either replaced or original. I'd guess replaced at some point. I'm not hopeful for lower temps given this but I'll see.

 

[2001LC]

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

Unfortunately after reading hundreds email, post and PM all on 100 series each day. I can't remember your year or if built. Added that info to your signture line, would be so helpful.

So I took the time to scroll back and read your older post again. I see you have and 06, correct?

 

[silver02accord]

Unfortunately after reading hundreds email, post and PM all on 100 series each day. I can't remember your year or if built. Added that info to your signture line, would be so helpful.

So I took the time to scroll back and read your older post again. I see you have and 06, correct?

Shoot I am sorry, yes I need to add that. I'll do right now. 2006 LX with 211k miles, ahc intact and neutral(thanks to you and other helpful members)