2UZ-FE Normal Operating Temperature (1 Viewer)

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Feb 29, 2020
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Hi Mudders!

I've searched the 100 series forums and couldn't find a definitive answer.

What is the normal operating temperature for the 2UZ-FE during normal driving conditions? In cooler and warmer climates?

I currently have a 98 with 169,000 miles still equipped with the original radiator that was recently flushed at Toyota. I installed my scangauge II and been reading 195-197 at its peak. Would like to know what is safe operating temperature for safe measure as I am running the original radiator.

Any feedback or personal experience would be greatly appreciated!
 
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220-225 is where I'd be worried.

My scanguage II shows that I generally run in the 195-198 range depending on climate.
 

Ayune

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New thermostat and coolant yielded a 182F operating temp for me. Was regularly above 200F before that.

Above all, keep coolant full in radiator. Overflow bottle level is something different.
 
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187F plus or minus a few degrees, with coolant system to spec. Whereas you may get up to 197 F when loading or very hot day.

Make sure radiator fins are cleaned.
 

geanes

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188 for engine temp and 158 for transmission are to my understanding the ideal operating temps. You will see fluctuations (more so in the transmission temps which will wildly vary based on if the torque converter is locked up or not). My engine temps can run as high as 198 in extremely high temps (100+). My thresholds for concern are 215 for engine temp and 210 for transmission temp. If I see those temps, I start to worry a little and take precautionary measures to mitigate those temps.
 
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188 for engine temp and 158 for transmission are to my understanding the ideal operating temps. You will see fluctuations (more so in the transmission temps which will wildly vary based on if the torque converter is locked up or not). My engine temps can run as high as 198 in extremely high temps (100+). My thresholds for concern are 215 for engine temp and 210 for transmission temp. If I see those temps, I start to worry a little and take precautionary measures to mitigate those temps.
To add to this, for reference, my trans runs around 110-115 in 4th with the torque converter locked, and around the stated 158 otherwise.
 
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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!
 
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It could definitely be the radiator. Might be good to do a proper flush of the radiator and see what comes out before installing a new one.

Also to note, just because the fan clutch spins with the engine, doesn't necessarily mean it's still good.

The 80 series guys used to say if you can stop the fan with a rolled up magazine with the engine running, then it's no good. Watch your fingers.

My test is that if I spin it with the engine off and it freewheels at all, then it's no good.
 

94SRUNNER

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I would test the fan clutch as described above. Additionally, I would make sure the radiator is free of debris. Lastly, it may be worth pulling the thermostat and one make sure it is in the correct orientation, i.e. the jiggle valve positioned at 12 o’clock and two insure the thermostat is operating correctly (as described in the FSM).
What is the status of the radiator cap? Those can affect the system.
 
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All good advise.^^^
With fan clutch, just replace it. These test are difficult to really make a good call on them. At 170K it's due, so is radiator cap.

Make very sure you've top coolant properly, burping all air out. This take a few days of checking each morning after 8 hr cool down. Have front end higher than rear end and look under the radiator cap. Make sure to drive for 15- 20 minutes night before with both heaters set to HOT.

Cleaning radiator fins is a must.

Additionally make sure engine tuned well. Vacuum leaks or spark plugs past usable life. Can also have you running hot. Make sure air filter, MAF and throttle body all serviced.
 
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I've been looking at ECT more lately. I'm wonder if all years the same, Or perhaps we've some difference.

98-02 100 series. ECT of 184-187 F.
One (99LC) has ~200K and original radiator. The other (00LX) 350K miles and aftermarket radiator.

I've found in these well tuned, w/freshly and fully serviced coolant system in 98-02 stock 100 series. I'm constantly getting 184 to 187 f ECT. I only touched on 190 f ECT, for a few seconds; with both A/C running full blast, in rush HWY hour stop and go gridlock traffic, hot sun day with OAT of 97F, at evaluation of 5,280 feet (The mile high city), 2 occupants after 6 hour demand mountain & city drive.

BTW: I used infrared temp gun, shot at back of thermostat housing to compare to my Bluedriver scanner ECT reads. Seems to match closely.
 
Last edited:
Joined
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San Diego North
 
 
if you have a 98 with the original radiator there is no question that it should be replaced. you are gambling every time you go somewhere at this point. these radiators have plastic tanks. the top tank will blow soon enough.
 

jerryb

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I'm just gonna say, I find it extremely difficult to believe any vehicle runs normally at 5-10 degrees higher than the starting point of the thermostat opening, 179.6°f plus or minus 4°f. I think you have to agree that if that is the case, the thermostat is never opening 100% (it can't be) Assuming 100% open on the plunger is 203°f and equal to 10mm of travel.
Anything is possible I suppose, if you see it on more than a few then it must be.

if you have any 100 on the original radiator there is no question.
 

flintknapper

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My original radiator gave up the ghost at around 190K miles. I would also see temps as high as 205 with that radiator.

Replaced it with a Spectra, coolant flush and fan clutch fluid mod. It runs between 188-191°F now. Have never seen it exceed 193° even on the hottest day. (been over 4 yrs now).
 
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jerryb

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I do believe it, I just hope my oil gets to at least 212°f. my own coolant temps is normally 195°f everything new in last 24 months. Even letting it idle in the garage for 30 minutes at 95°f out. Probably shouldn't include 08/2002 and earlier as a reference.
 
Last edited:
Joined
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Boise, Idaho
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!
I believe you should have the auxiliary electric condenser fan on your '98. In addition to what everyone else said, I'd check to make sure it's turning on.
 

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