2UZ-FE Normal Operating Temperature (2 Viewers)

94SRUNNER

GOLD Star
Joined
Oct 9, 2006
Messages
3,614
Location
Dayton, OH
 
 
Okay, so I just replaced my thermostat (and other things) and the temps aren't right, although my heater is blowing super hot now, which it wasn't before.

Driving around town right now with the OAT at about 60-70F (no heat and no AC) the ultra gauge shows 185F for a while, but it keeps creeping up to about 188 and then will spike at 190-192 for brief periods but then go back down to 188. But what I noticed that's weird is that when I come home, I am going about 25mph up a hill and then let off the gas, turn right, and then go down a hill. When I do this the temp jumps to 192 almost immediately. VIDEO but then cools back down to 188.
These coolant temperatures you have listed above, as well as the behavior of the observed coolant temp fluctuations, IMO are completely normal and I see similar patterns in my system.

Nothing to worry about.
 
Joined
Nov 4, 2007
Messages
10,113
Location
Colorado
 
 
What's your mileage?

In the mile high city. I'd say your running hot. But regardless of altitude. That rapid ECT fluctuation, on a cool evening in lower RPM and speeds, is not what I'd see after a complet baseline. In a stock 98-02 with engine, properly turned and all but lower foam around radiator. I'd see 184-187F ECT in most all driving condition from 5,000' to 9,000' ASL. W/both AC on full or off, at OAT between 60F & 97F.

Did you clean your radiators fins (all 3). I see no mention of doing so.

Fan clutch can be difficult to diagnose. Additionally they may build up crud on the face of fan in the coil. This can interfere with coils operation. Clean it as you clean the radiators. It can take hours and repeated attempts to clean the radiator fins. Really take the time to do a thorough job and come back often at it.

New radiator OEM cap is a must.

Confirming the tube and cap between radiator and reservoir, is free of obstruction. Confirm reservoir tube goes straight the the bottom of reservoir. Very important.

The fact you replaced water inlet & cap. Suggest to me, you had electrolysis. That is a system that was not well care for with all OEM products from day one.
I only use, Toyota red mixed 50/50 with distilled water in the 89-03. Additionally in older systems. It's not a bad Idea to chemically flush with BG Clean and add BG Cool. Make sure block is triple drain and blow out the system each flush/drain.

On other notes:
I notice your BK 1 LT FT reading in the negative. whereas BK 2 LT FT running a more normal to what I see, in positive. I'd run BG44k in halve tanks of gas (about 12 gallons) and Chevron techron in another. Alternating one bottle at a time, for 4 tanks. Or better better yet; rebuilt all fuel injectors, replacing all seals. Making sure top of engine is spotless before doing so. You do not want even dust dropping into intake ports. Replace fuel filter also. Additionally verfly not vacuum leaks. This includes the two vacuum lines coming up from idle up control of vane pump (power steering pump).. Replace fuel filter if never done, is good PM.

Has starter ever been replaced. Were intake gaskets replaced at that time. Was top of engine cleaned before doing so. A compression check, can be revealing. So very often shops or even more so DYI ,drop sand down the intake ports from not clean top of engine pre disassemble..

BTW: Did you replace PCV grommet. 98-02 grommet shrink and we lose vacuum and blow oil out around grommet.

What's condition of spark plugs and coils.

Make sure you've a good OEM air filter and seal of filter did not get pinched.

Don't get frustrated, just get all systems back to spec. Frustration starts when they are.;)
 
Last edited:
Joined
Oct 3, 2014
Messages
679
 
Denver based 99 LC here. 216K miles with TRD supercharger (with 9th injector). I'm running a URD 170* thermostat and see temps in the 185-195 range; I typically see hit the upper range (192-195) when climbing up hills.
 

Nightbrew

SILVER Star
Joined
Jan 20, 2013
Messages
507
Location
Missouri
 
Okay, so I just replaced my thermostat (and other things) and the temps aren't right, although my heater is blowing super hot now, which it wasn't before.

Driving around town right now with the OAT at about 60-70F (no heat and no AC) the ultra gauge shows 185F for a while, but it keeps creeping up to about 188 and then will spike at 190-192 for brief periods but then go back down to 188. But what I noticed that's weird is that when I come home, I am going about 25mph up a hill and then let off the gas, turn right, and then go down a hill. When I do this the temp jumps to 192 almost immediately. VIDEO but then cools back down to 188.

It does this EVERY SINGLE TIME. If it was 100F outside and I was blasting the AC I wouldn't be surprised by these numbers, but they seem hot given how cool it is outside. I also don't like the rapid fluctuations.

Here is what I did:

99 LX470
  • New OEM Thermostat (jiggle valve at the top)
  • New thermostat housing
  • New housing over the top of the thermostat
  • New serpentine belt
  • New PCV valve/hoses
  1. Refilled coolant and ran it until it warmed up, then shut down, added coolant to the overflow tank.
  2. The next morning I topped off the radiator then drove it to work. Parked on a slope. I did this three times. Each time I had to add a little coolant.
  3. Put one of those funnels to help bleed the air out, didn't really notice any bubbles coming out.
  4. Drove around a bit tonight and saw the same behavior. Parked on the steepest part of my driveway to check on it again tomorrow.
Getting a little frustrated...
I may be able to help with this, within the next week or so. I would expect mine to do the same thing. Gain a few degrees going up mild hills, and then back down. I am currently in the middle of a cooling system overhaul. So once I am back on the road, I will report back.
 
Joined
Apr 27, 2017
Messages
193
Location
West Coast
I may be able to help with this, within the next week or so. I would expect mine to do the same thing. Gain a few degrees going up mild hills, and then back down. I am currently in the middle of a cooling system overhaul. So once I am back on the road, I will report back.
That would be great. But the more I think about this the more I think about how many 100 series drivers are out there just happily tooling about in their ignorant bliss and the ECT temps go up and down but they never know any better because it's not moving the needle and while it might be running hotter than a new truck it's still not in the danger zone.
 

Nightbrew

SILVER Star
Joined
Jan 20, 2013
Messages
507
Location
Missouri
 
That would be great. But the more I think about this the more I think about how many 100 series drivers are out there just happily tooling about in their ignorant bliss and the ECT temps go up and down but they never know any better because it's not moving the needle and while it might be running hotter than a new truck it's still not in the danger zone.
Tru dat. But two sayings to think about.
Ignorance is bliss.
Knowledge is power.
Pick one of the two, and live with results.
 
Joined
Nov 4, 2007
Messages
10,113
Location
Colorado
 
 
Denver based 99 LC here. 216K miles with TRD supercharger (with 9th injector). I'm running a URD 170* thermostat and see temps in the 185-195 range; I typically see hit the upper range (192-195) when climbing up hills.
@gungriffin runs with TRD. He also has lower temp thermostat as you and different spark plugs than stock. IIRC he's running cooler than you.
 

Ramathorn15

Supporting Vendor
Joined
Jan 8, 2016
Messages
1,687
Location
ABQ NM
Didn't read the whole thread, but make sure your radiator is clean. I had a customer come in for a timing belt in a extremely clean 2006 LX with 180k for a timing belt. Radiator looked great on the back side. Once I pulled it, it looked like this. The condesor being sandwiched against the front of the radiator can really trap grime. You can't even get to this section with a hose because of the fan shroud.

 
Joined
Nov 4, 2007
Messages
10,113
Location
Colorado
 
 
I see the same, time and time again. I now regularly clean radiator as I clean engine before timing belt job. As part of coolant system service. Sometimes hours of HP washing, come back again and again from all angles. Even after all that washing, I find they (all 3 radiators) need more cleaning after I pull the engine radiator.


007.JPG

Even with skid on, a flashlight will reveal the cloggs.
Radiator.JPG

I've even found styrofoam between them, with full skids on and all foam. I suppose standing in high water and floated in.
Old Radiator (6).JPG




 
Joined
Sep 16, 2020
Messages
41
Location
knoxville, TN
Alright, I know its been hot here in Vegas at 112 today but I've noticed my temperature hitting 215-218 on the scangauge with my AC on while I was in the drive thru today, which is getting me worried. But while driving, I eventually get back down to 188/190

I have done the following PM work with all brand new Toyota OEM parts within the past 3 months.
-WP & TB
-Thermostat
-Crank Seal
-Upper and lower radiator hoses
-Refilled system with fresh Toyota Red long life coolant

What I haven't done is change the radiator, which is still original and I'm currently at 170k. Clutch fan engages and stays rotating when engine is on.

Anyone have an idea why I'm hitting over 200? Maybe its time for a new radiator? Thermostat rotation placement?

Any feedback would be appreciated! Thanks in advanced!
How was it replacing the crank seal? I think I need to replace mine. I have the fan and shroud off right due to replacing the clutch. I am seeing oil down there.
 
Joined
Apr 30, 2020
Messages
297
Location
San Diego, CA
I see the same, time and time again. I now regularly clean radiator as I clean engine before timing belt job. As part of coolant system service. Sometimes hours of HP washing, come back again and again from all angles. Even after all that washing, I find they (all 3 radiators) need more cleaning after I pull the engine radiator.


View attachment 2454104
Even with skid on, a flashlight will reveal the cloggs.
View attachment 2454102
I've even found styrofoam between them, with full skids on and all foam. I suppose standing in high water and floated in.
View attachment 2454108



Did a longer road trip today only up to 4k feet but Temps were just shy of 100. Even idling with a/c on the ect temp did not get above 190 degrees and while driving was in the 181-186 range primarily. I was seeing over 200 before I replaced the fan clutch a while back few weeks ago. Also replaced the lower and upper rad hose and water inlet so one of those had something to do with it. I was seeing trace amounts of coolant on the water inlet I think from lower rad hose micro leak. This is an 06 LX
 
Joined
Nov 4, 2007
Messages
10,113
Location
Colorado
 
 
Did a longer road trip today only up to 4k feet but Temps were just shy of 100. Even idling with a/c on the ect temp did not get above 190 degrees and while driving was in the 181-186 range primarily. I was seeing over 200 before I replaced the fan clutch a while back few weeks ago. Also replaced the lower and upper rad hose and water inlet so one of those had something to do with it. I was seeing trace amounts of coolant on the water inlet I think from lower rad hose micro leak. This is an 06 LX
Good info thanks. That lower than 98-02's 184-187F. OAT of 100F, ECT 181-186 is a few degrees lower than I'd expect. Fan clutch, for sure would have been your greatest factor in reducing ECT.

I Don't recall. Any of below done or replaced:
Thermostat
Radiator Cap. Radiators fin washed out.
All vacuum line checked. leaky ones replaced.
 
Joined
Apr 30, 2020
Messages
297
Location
San Diego, CA
Good info thanks. That lower than 98-02's 184-187F. OAT of 100F, ECT 181-186 is a few degrees lower than I'd expect. Fan clutch, for sure would have been your greatest factor in reducing ECT.

I Don't recall. Any of below done or replaced:
Thermostat
Radiator Cap. Radiators fin washed out.
All vacuum line checked. leaky ones replaced.
Yes all of that has been done. OEM cap, oem tstat both new. replaced several vaccum lines, pcv valve, fuel filter, fuel pump, fuel pressure regulator. washed radiator fins. going to add the skids back on soon will update with new numbers but ambient temps will be cooling down soon
 
Joined
Nov 4, 2007
Messages
10,113
Location
Colorado
 
 
So I see this is a very good example of ECT in a properly tuned & running VVT 06-07 with very mild build (ASFIR Skid). 181-186F w/OAT of 100 AC on in the sun. at SL (Sea level) to 4k ASL. I assume side and top foam around radiator.

Thanks so much for posting. Getting these base line or important.


Did a longer road trip today only up to 4k feet but Temps were just shy of 100. Even idling with a/c on the ect temp did not get above 190 degrees and while driving was in the 181-186 range primarily. I was seeing over 200 before I replaced the fan clutch a while back few weeks ago. Also replaced the lower and upper rad hose and water inlet so one of those had something to do with it. I was seeing trace amounts of coolant on the water inlet I think from lower rad hose micro leak. This is an 06 LX
Good info thanks. That lower than 98-02's 184-187F. OAT of 100F, ECT 181-186 is a few degrees lower than I'd expect. Fan clutch, for sure would have been your greatest factor in reducing ECT.

I Don't recall. Any of below done or replaced:
Thermostat
Radiator Cap. Radiators fin washed out.
All vacuum line checked. leaky ones replaced.
Yes all of that has been done. OEM cap, oem tstat both new. replaced several vaccum lines, pcv valve, fuel filter, fuel pump, fuel pressure regulator. washed radiator fins. going to add the skids back on soon will update with new numbers but ambient temps will be cooling down soon
 
Joined
Nov 4, 2007
Messages
10,113
Location
Colorado
 
 
So it's looking more and more like; all stock 100 series. ECT 184-187F (+ or- a few degree f) is normal.
 
Joined
Apr 30, 2020
Messages
297
Location
San Diego, CA
So I see this is a very good example of ECT in a properly tuned & running VVT 06-07 with very mild build (ASFIR Skid). 181-186F w/OAT of 100 AC on in the sun. at SL (Sea level) to 4k ASL. I assume side and top foam around radiator.

Thanks so much for posting. Getting these base line or important.
Yes foam on radiator all around, but front skid was not on for these numbers. My next Temps will be with sliders installed as well as front rear and mid skid I'll report back. Lt fuel trims are around 0.75
 

jerryb

Supporting Vendor
Joined
Jul 30, 2016
Messages
2,120
Location
pensacola fl.
If I had a large audience I certainly wouldn't be advocating people spend money chasing the lowest temp possible.
Half the audience probably thinks the temp gauge is oil related in the first place, 20 year old sensor an'all. What's the +or- number again?
 

abuck99

SILVER Star
Joined
Nov 8, 2015
Messages
4,343
Location
ATL
 
Found this new Aluminum option. Who's going to be an early adopter test pilot......

 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top Bottom