I saw 207 today on a 102 degree day with the A/C going, think I will start here. I have a new radiator sitting there just no time to get it done
Last edited:
2UZ-FE Normal Operating Temperature (6 Viewers)
- Thread starter Rpreme
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
I’m getting the same coolant temps on my wifi obd as yours in the 204°F range especially on stops. I placed a marker sticker on the coolant reservoir for hot and cold levels. I check on that every time I get home. This gives me a visual status check if I am loosing coolant on this brutal heat. So far it hasn’t, we just want to make sure that there is no internal or external leak on the coolant.
Its more important to check the levels in the radiator. Overflow reservoir can vary a lot.
2001LC
SILVER Star
Very true ^. Coolant reservoir fluctuate greatly with OAT and or engine coolant temp (ECT). It's why I note OAT and check level in Radaitor and reservoir just before sunup.
I' get 184f to 187f ECT, with momentary raises to ~190F. In the 98-02 with both AC 's on max in 100F OAT, in the afternoon full sun. In 9 out of 10, 98-02 that have done a full coolant service and tune on.
But yesterday, I had one act more like the VVT. It ran a little hotter with OATs in the 70F or below at 185F to 189F. But once OAT got into 80F+, ECT got into the 190's averaging 194f, hitting 197F when I'd load her up (pulling up hill AC on). ??? WHY!
I thought perhaps I put a VVT fan clutch in. Checked, nope! it was the thinner non VVT I'd just install.
Perhaps old fuel filter reduce fuel delivery? But fuel trims, look okay, perhaps a tad lean.
Perhaps older non OEM fan belt, but seem okay. Just slick back and a tad long. It could be slipping a tad?
Then I found a head gasket leak, darn! Seem very minor and no sign of coolant entering cylinders or oil. But will need to do more testing (combustion gas, compression and scoping). At this point, it would seem head gasket leak may be pushing up ECT.
I had just done full coolant service with chemical flush (block drains clogged). Likely someone add a head gasket stop leak, which is likely why drains clogged. It seems, I flushed an leak became active again. I was jump over 203F in 80F OAT at every stop (stop at red lights), before coolant service & tune. Now ECT just goes up when I really push engine hard and OAT over 80F. So big improvement. But DARN, A HEAD GASKET LEAK.
I' get 184f to 187f ECT, with momentary raises to ~190F. In the 98-02 with both AC 's on max in 100F OAT, in the afternoon full sun. In 9 out of 10, 98-02 that have done a full coolant service and tune on.
But yesterday, I had one act more like the VVT. It ran a little hotter with OATs in the 70F or below at 185F to 189F. But once OAT got into 80F+, ECT got into the 190's averaging 194f, hitting 197F when I'd load her up (pulling up hill AC on). ??? WHY!
I thought perhaps I put a VVT fan clutch in. Checked, nope! it was the thinner non VVT I'd just install.
Perhaps old fuel filter reduce fuel delivery? But fuel trims, look okay, perhaps a tad lean.
Perhaps older non OEM fan belt, but seem okay. Just slick back and a tad long. It could be slipping a tad?
Then I found a head gasket leak, darn! Seem very minor and no sign of coolant entering cylinders or oil. But will need to do more testing (combustion gas, compression and scoping). At this point, it would seem head gasket leak may be pushing up ECT.
I had just done full coolant service with chemical flush (block drains clogged). Likely someone add a head gasket stop leak, which is likely why drains clogged. It seems, I flushed an leak became active again. I was jump over 203F in 80F OAT at every stop (stop at red lights), before coolant service & tune. Now ECT just goes up when I really push engine hard and OAT over 80F. So big improvement. But DARN, A HEAD GASKET LEAK.
07 LC here in central Florida. Saw my temps start to creep up a little. It’s been about 90F out.
191-193F driving and 195-198F at a stop
Aisin timing belt kit, Kuzeh t stat, and OEM radiator done about 50k ago by previous owner.
Replaced thermostat OEM, fan clutch Aisin, upper/lower hoses w/ clamps OEM, and belt Bando today. After driving about 50 miles I now see:
186F-191F driving and 191-195 at a stop. Will drive it over the weekend and continue to monitor but it definitely improved it.
191-193F driving and 195-198F at a stop
Aisin timing belt kit, Kuzeh t stat, and OEM radiator done about 50k ago by previous owner.
Replaced thermostat OEM, fan clutch Aisin, upper/lower hoses w/ clamps OEM, and belt Bando today. After driving about 50 miles I now see:
186F-191F driving and 191-195 at a stop. Will drive it over the weekend and continue to monitor but it definitely improved it.
Your 07 is going to run hotter. That is by design. My 07 LX is regularly 192-196 in the warm months. I see 198-201 every so often on days over 100F but it never stays there. I only see 189 on sub 32F days.
I know the VVT models tend to run warmer but I figured an additional data point is always good to have and at this point everything should be 100%.
Agree!
Are you running FCT075 (thicker fins for VVTi) or FCT021 (thinner fins)?
I'm running 16210-50102 from Toyota, which is the thicker version.
2001LC
SILVER Star
Always happy to see data points 
When I see, ECT climb while at stops sign. I'll clean radiator fins, and test fan clutch at same time with water pressure. I also check coolant level in rad under cap. Also level and function of expansion tank which includes rad cap.
forum.ih8mud.com
When I see, ECT climb while at stops sign. I'll clean radiator fins, and test fan clutch at same time with water pressure. I also check coolant level in rad under cap. Also level and function of expansion tank which includes rad cap.
Radiator fins need cleaning! Alert Alert Alert
I've a 06LC w/192K I just bought. In reading history I found PO complained of engine temp raising when both front and rear AC on. Toyota Dealership diagnosed with clogged radiator fins. Recommended new OEM radiator, $600 for the US spec Radaitor plus coolant and labor. They should have added...
forum.ih8mud.com
Last edited:
FCT075
Put about 150 miles on it today.
Hung pretty much at 188F running 75-80mph. I hit 195F for a second sitting at an off ramp after the highway.
In my 1999, I would see temps creep above 205-210 degrees on hot North Texas days, which is basically all summer, even with a fully refreshed cooling system including new coolant, radiator, thermostat, fan clutch, fan, and hoses.
I finally drained and refilled the Aisin blue fan clutch with 30k cst fluid. It was severely underfilled from the factory. Now it holds 189 degrees at idle and 190 to 192 degrees on the highway. AC temps also dropped by 6 degrees, measured with a meat thermometer. I also have the auxiliary fan.
I finally drained and refilled the Aisin blue fan clutch with 30k cst fluid. It was severely underfilled from the factory. Now it holds 189 degrees at idle and 190 to 192 degrees on the highway. AC temps also dropped by 6 degrees, measured with a meat thermometer. I also have the auxiliary fan.
Whist I understand the improvement at idle or low speed, it doesn’t really make sense why temps dropped at highway speeds. The fan is pretty redundant at high speeds unless you’re crawling very slowly laboring up a mountain pass.
Sorry for the confusion. Temperature would creep at idle only. Usually when picking up kids from school waiting in line, bumper to bumper traffic, or prolonged idling where I would need to set it in park and accelerate to get the fan moving. No issues with highway speeds.
Last edited:
Jack90210
SILVER Star
Barring other obvious symptoms, steps 1 and 2 are (IMO) always:
1) check coolant level and quality
2) clean radiator fins
Pretty much every radiator I've seen (in photos) that has been removed from these vehicles has substantial debris on the fins, which is the likely reason for people who install aftermarket radiators to say "It runs so much cooler with a [insert brand here] radiator!"
1) check coolant level and quality
2) clean radiator fins
Pretty much every radiator I've seen (in photos) that has been removed from these vehicles has substantial debris on the fins, which is the likely reason for people who install aftermarket radiators to say "It runs so much cooler with a [insert brand here] radiator!"
shtbrwn86
SILVER Star
I’ve replaced the radiator, new oem fan clutch, radiator hoses, thermostat and I still see temps get up into the low 200s going over a mountain pass or 80mph in the summer. Never figured it out.
99 LX
2001LC
SILVER Star
Assuming all ALL OEM. Thermostat jiggle valve at top, NO AIR in radiator/system and expansion tank hose working as it should. I'd then run logs on: fuel trims, RPM. MPH, ECT and MAF.
I'd also wash fin of radiators, often.
Radiator fins need cleaning! Alert Alert Alert
I've a 06LC w/192K I just bought. In reading history I found PO complained of engine temp raising when both front and rear AC on. Toyota Dealership diagnosed with clogged radiator fins. Recommended new OEM radiator, $600 for the US spec Radaitor plus coolant and labor. They should have added...
forum.ih8mud.com
Next is EVAP system.
I have been battling high ECT in my ‘99 LC since last summer. The lowest it ran was 194F.
It’s currently running 203F on highway and stop and go is going up to 215F!!
My kids are getting red!!
AZ with 115F ambient temps. At midnight it’s still 100F out!
Modified Aisin clutch fan with 40k fluid
New koyorad radiator
Timing belt and Aisin water pump done 1 year ago
New Ac condenser
New AUX fan
Coolant system bled
Red coolant
New Toyota ATF (every drop)
Heater tees done with new hoses
Basically it can’t be the cooling system!
I replaced everything except the heater cores
Even with the heater on the temps are at 203F
I do have CEL but it was running hot before that. My other 100 series was running at 190F and at a stop the temps would go up over 204F but would drop down to 190F. (Unfortunately this truck has a blown head gasket)
It’s currently running 203F on highway and stop and go is going up to 215F!!
My kids are getting red!!
AZ with 115F ambient temps. At midnight it’s still 100F out!
Modified Aisin clutch fan with 40k fluid
New koyorad radiator
Timing belt and Aisin water pump done 1 year ago
New Ac condenser
New AUX fan
Coolant system bled
Red coolant
New Toyota ATF (every drop)
Heater tees done with new hoses
Basically it can’t be the cooling system!
I replaced everything except the heater cores
Even with the heater on the temps are at 203F
I do have CEL but it was running hot before that. My other 100 series was running at 190F and at a stop the temps would go up over 204F but would drop down to 190F. (Unfortunately this truck has a blown head gasket)
2001LC
SILVER Star
To be clear:
Toyota (RED) LL & D-water 50/50.
New OEM Thermostat, jiggle valve up.
New OEM radiator cap.
All air bleed from coolant system, over a period of at least 3 heating and cooling ( 8 hr) cycles.
Radiator fins cleaned (all 3).
Get more data points:
Run logs on Fuel trims both long & short. Engines that runs lean, runs hot. Best log RPM & MPH with FT.
Toyota (RED) LL & D-water 50/50.
New OEM Thermostat, jiggle valve up.
New OEM radiator cap.
All air bleed from coolant system, over a period of at least 3 heating and cooling ( 8 hr) cycles.
Radiator fins cleaned (all 3).
Get more data points:
Run logs on Fuel trims both long & short. Engines that runs lean, runs hot. Best log RPM & MPH with FT.
Everything you have mentioned I have done. Although I will do some more bleeding. My gold 100 series was always nice and cool and had not had any replacement parts except maybe the clutch fan. I’ve had to top the coolant off and never bled it! Great temps as well 190F.
There is a big difference in running temps and the black truck has all new cooling components. It’s frustrating! I will data log the O2 sensor readings and voltages but I do not know how to interpret them.
There is a big difference in running temps and the black truck has all new cooling components. It’s frustrating! I will data log the O2 sensor readings and voltages but I do not know how to interpret them.
Reporting back after 100+ degree days. Vehicle runs cooler than it did pre clutch fan drain with 30k cst fluid. Highway driving in the summer the ECTs are 189-191 with no vehicles directly in front of me. Went through a busy drive thru and temps started creeping up more slowly than usual ~205 degrees until I set it in park and accelerated a bit to get the fan moving. Transmission temp was up ~200 degrees. Accelerating drops the temps for both ECT and Transmission. Once I start driving again the temps drop quickly. Noticeable difference in HVAC temp.
No issues in colder weather but this heat is brutal.
No issues in colder weather but this heat is brutal.
