2UZ-FE Normal Operating Temperature

[abuck99]

Mine seems to operate fully (when I hear the roar) at around 195. However, when driving on the highway, isn't the fan redundant due to the natural increased airflow? If pulling hard up a mountain pass towing, it may then be needed. This is how my diesel landcruiser has behaved.

Yeah - you want your fan to slip more at hwy speed otherwise it rob's some power and increases your fuel consumption.

 

[shtbrwn86]

Not knowing your year, stock or built. Makes difficult to say if that is what your best ECT can get down to. Adding that info to the signture line would be helpful.

If all stock, that's on the high side for 98-02.
With steel bumpers and winch OAT 95-100. The 192-195f ECT with A/C on, sounds about right, but on high side.

There may be more you can do. Like washing the condenser and transmission oil cooler radiators, tune up, transmission flush. I'll assume that is a new fan clutch, based on statement "only thing left to do".

Added this info to my signature. And yes, the fan clutch was replaced in the last few years by the dealer, although I have not tested it yet.

 

[2001LC]

So I just thought I'd update anyone who was following my search of lowering my temps. Did a 2000 mile roundtrip, AC on, outside temps between 78-98. Cruising at GPS 78 mph, temps fluctuated from a low of 195 to 203. Couple traffic times, temps went as high as 205. Stayed in that range well. This seems OK? Although many people report temps of 185-190 cruising. Not sure why. New stat I put in was a 82C.

Is there any reason to replace the Coolant temperature sensor as part of PM? I was trying to link a thread where a guy replaced because a code was thrown and his old one looked really bad.

Well I'm not sure what more to do. Here's a refresh what I've done.

- New OEM fan clutch
- New OEM thermostat
- Radiator about 3 years old - Not OEM and doesn't have foam.
- All radiators washed very well.
- Over the last two years, the trans fluid has been changed about 6 times from the sump.
- Coolant was changed a year ago with Toyota Red.
- Rad cap is not OEM and has a 0.9 BAR, but cap pressure doesn't affect running temps. It changes your boiling temp.
- Coolant system bled with method suggested in this thread. This lowered temps 3-5 degrees from initially fitting Stat.
- TB and WP done at 224k. 240k miles currently on truck.

Advice on where to go from here?

I agree, should not affect ECT. Provided it allowing proper flow of coolant in and out of reservoir. But recheck level under cap periodically, after 8 hour cool down, with heaters set to hot the drive before cool down. The check needs to be when cool OAT in the morning out of the sun, and with front higher than rear of vehicle, to get best results.

What I have found with non OEM caps. They do not fit as tight. That when I pressurizing system for test or to blow out during a flush, with ~10PSI into rad through reservoir hose. I'll see and hear leakage out of non OEM caps.

Once coolant system to spec. Which includes the foam arounds side and top of radiator (lower foam seems to have less effect). Tune engine and make sure no vacuum leaks and PCV valve working. Also run a fuel system cleaner through the gas. I like 44k and or Chevron Techron (at different times). I also have been using IK20TT denso spark plugs. Don't have any comparison to non TT, but may drop cylinder head temp a tad, but IDK.

Watch fuel trims too see if running lean.

I just learned from @abuck99. That the coil on front of fan clutch, even new OEM. Are reportedly varying from one to another.

Based on your year, you are running hot IMHO.

Look at fuel trims get logs if you can while driving seeing these high temp..
Install foam on top and sides of radiator.
Use a IR temp gun shot at water bypass joint front, next to ECT sensor.
Wash all radiator fins. You may have clogged since replacement and or never cleaned other 2 radiators.
Tune engine. Make sure no vacuum leaks.
Use OEM cap.
Re-check coolant level.

 

[silver02accord]

I have an Aisin fan clutch arriving today which I plan on installing as I am on the original fan clutch. Also, I have been monitoring coolant levels since changing the tstat and the Coolant has dropped (little by little) over several days of operation. I just added some more that I mixed and it seems to be dropping less each time I check. It's something you probably would not normally notice but I've been reticent sinxe I changed tsat.

 

[phatdragon]

Following this. I am getting temps creeping up especially towing a 5,000lb trailer. 210 WT after a long pull up about 2000 ft, 199 trans temp. Medium weight 2002, with 157k on the clock, original radiator from what I can tell. I base-lined all fluids last year. I live at 5500 feet above sea level and regularly go to 12000+ ft. I don't notice high operating temps wheeling but do sometimes in 95 degree heat in stop and go traffic (occasionally over 200, but seems to idle at about 192). Radiator and overflow tank are both full when cold.

I asked in another thread but has anyone used the 3 row all aluminum radiators sold on ebay for the hundys? I tend to go OEM, but these look pretty slick for the price.

 

[Beau]

What I'm finding is the engine is pretty capable at keeping temps between 195-205 no matter how much I push it. It could be raining very heavy and driving 70 mph and I'll see temps around 192. On other cars and my other landcruiser, temps would drop about 5-15 degrees when it's raining as the radiator is cooled very quickly. Thus I would expect to see temps fall into the 180's. Not happening here though. It's as though the thermostat is running on a tight range keeping the engine within this spec no matter how much additional cooling is thrown as it.

I sprayed a hose water into the rad at idle and temps would not go below 195. What does all this tell you guys? Maybe this replacement rad put in 3 years ago is just crap? I'm tempted to run a lower degree stat and see what happens.

 

[flintknapper]

I'm tempted to run a lower degree stat and see what happens.

Your engine temps will still reach a 'high point' it will just take a bit longer to happen. A lower degree T-Stat simply opens up earlier than one with a higher rating, it can NOT compensate for issues elsewhere in the cooling system.

Once a T-Stat is fully open (regardless the temp rating) it is doing all it can do (allowing as much flow as is possible). It is then up to the rest of the cooling SYSTEM to handle the load. A good radiator, properly working radiator cap, fresh coolant and properly working fan clutch are what I'd be looking at.

 

[2001LC]

Yeah I've been looking for what factory consider normal operating temp range. I do suspect we've variation in the years and milage of engine. But I'm sure hitting 197F or higher in normal driving, is indication of system issues that needs correcting. 06-07 I've biggest question on as to what is "normal" from factory. But I do have logs indicating that 187F (high I hit) is baseline in the 06-07. That with full metal skids and belly pan, the temps jump up to ~192F average (w/o heavy bumpers). That was Merlot 07LC w/63K miles. In it, I did hit in the 201F when I ran it up (high RPM run) w/bellypan, trying to heat CATS. So was not a good ECT test. It also was without doing a full coolant system service. But just driving around with the full metal skids and belly pan, it did run hotter.

Lately I've been looking more 98-02. Which I see consistently 184 to 187 F in well turned engine. The two I'm looking at currently, are high mileage. With high mileage comes wear. So they are looser running engine presumable. I suppose that would likely mean less friction and as such low temps may by a few degrees.

Today I'll be running short term logs on a heavy 05LC, no bell pan or #1 or #2 skids on. I just serviced coolant system. Engine seem okay no apparent vacuum leaks, with report newer spark plugs. Does have some unusually wiring. One wire is tap into #1 coil??. Some fuel injector wires have been spliced. Seem to run okay. It's actually a Tundra long block in it, of unknown year and mileage. I did find it had non OEM thermostat and rad cap. It was running cool ( no boiling issues) ~187F. I'll report back on its temps.

Here is the 05LC (Tundra block) heavy, No skids or belly pan, I just service coolant system. City HWY 40 minute driving.
OAT 91 to 94F. ECT ~187F average.
ECT Jump to 190 to 194F with both A/C on full. High temps at stops.

Notes: RH block drain plug not drained, plug frozen. Age of fan clutch unknown. Heavy steel bump and winch made cleaning radiator more difficult and less effective. Spark plugs non TT, believed to have 30K on them. Transmission fluid condition and level unknown.

 

[94SRUNNER]

@2001LC remind me how are you tracking ETCs on these rigs you work on?

 

[2001LC]

I've a BlueDriver that streams date to my iphone. It keeps logs, that I email to myself. For VVT engines, it also picks up CAT temps.
However, it does not pick-up of transmission temp, as of my last firmware or driver update.

 

[geanes]

My rig is really starting to drive me nuts. Just replaced the t-stat and O-ring today along with fresh 50/50 Toyota coolant. Have been running a little hot over the past few months (193-198). Driving around, I'm still hitting 198. Hit 202 idling for a minute. Ambient temps are 83 degrees. Fan spins about 1/4 turn by hand before stopping, so the clutch seems fine. The radiator is clear and no bent fins. I had installed a CSF radiator and new hoses a few months back and the rig has always run "hotter" than it had before. It used to hold 188 like clockwork regardless. All of this "hotter than normal" stuff started after the notorious debacle back in January when a dealer did my steering rack replacement, failed to put coolant back in and let me drive away leading to a near catastrophic engine overheat (260 on the Scangauge). Really starting to worry something is going south in my engine leading to higher than normal temps. Fingers crossed that's not the case.

 

[2001LC]

A few thoughts:

• Transmission needs topping after radiator replacement.
• New OEM radiator cap with new radiator, always.
• OEM thermostat is best and must have jiggle valve position at top.
• Are you checking coolant level in radiator after 8 hour cool down (with front of vehicle higher than rear, is best).
• Is reservoir hose straight and dropping to bottom of reservoir tank. I see these hung-up on shelve bent, often.
• Check reservoir hose & cap for obstructions. I've found these plugged!
• Make sure all three (engine coolant rad, condenser and oil cooler) radiators fins are clean.
• Watch your fuel trims. Short term running lean (-) may indicate vacuum leak or weak or poor fuel injector spray.
• Try spinning fan cold. After a few turns it should loosen up. It can also be stopped with a rolled up newspaper, during warmup. After warm up, as fan clutch gets hot, it will make a loud fan (turbo) sound. Than it can't be stopped by a rolled up paper.
• Any change in oil pressure since 260F overheat.

Is coolant level holding? I ask because number one damage from overheating is warped heads. The head gasket than leaks. Coolant level than drops in most cases, but may be very slow to do so.

If everything check out. Next would be compression test w/leak down test. Also, overnight coolant system pressure test.

If you get up to Denver stop in.. I can take a look!

 

[Eyedaho]

My rig is really starting to drive me nuts. Just replaced the t-stat and O-ring today along with fresh 50/50 Toyota coolant. Have been running a little hot over the past few months (193-198). Driving around, I'm still hitting 198. Hit 202 idling for a minute. Ambient temps are 83 degrees. Fan spins about 1/4 turn by hand before stopping, so the clutch seems fine. The radiator is clear and no bent fins. I had installed a CSF radiator and new hoses a few months back and the rig has always run "hotter" than it had before. It used to hold 188 like clockwork regardless. All of this "hotter than normal" stuff started after the notorious debacle back in January when a dealer did my steering rack replacement, failed to put coolant back in and let me drive away leading to a near catastrophic engine overheat (260 on the Scangauge). Really starting to worry something is going south in my engine leading to higher than normal temps. Fingers crossed that's not the case.

If your fan clutch is original, it might be worth replacing it for <$100. My rig was getting warm when idling with the AC on, and a new clutch seems to have resolved it. Since the clutch isn't locked up, I suspect that they may spin at a lower % RPM as they age, but that's just my suspicion.

 

[shtbrwn86]

If your fan clutch is original, it might be worth replacing it for <$100. My rig was getting warm when idling with the AC on, and a new clutch seems to have resolved it. Since the clutch isn't locked up, I suspect that they may spin at a lower % RPM as they age, but that's just my suspicion.

How long are fan clutches good for? Mine was replaced at the dealer 3 1/2 years ago.

 

[Eyedaho]

How long are fan clutches good for? Mine was replaced at the dealer 3 1/2 years ago.

I'm not an expert on that by any means. I would expect much longer than 3.5 years for an OEM one.

 

[shtbrwn86]

I'm not an expert on that by any means. I would expect much longer than 3.5 years for an OEM one.

So this might be a stupid question but how much do the bottom skid plates impact engine temps? I took mine off a few months ago and haven't put them back on yet. I'm still monitoring my temps after installing the new thermostat but I just wonder if temps will go up a bunch when I put the plates back on.

 

[geanes]

If your fan clutch is original, it might be worth replacing it for <$100. My rig was getting warm when idling with the AC on, and a new clutch seems to have resolved it. Since the clutch isn't locked up, I suspect that they may spin at a lower % RPM as they age, but that's just my suspicion.

Replaced the fan clutch last year. Everything checks out with it. I'm beginning to wonder if my Slee skid plate combined with the winch is the cause of the higher temps. What's weird though is that the temps rise with the RPM. If I just idle, I'll sit around 193 (still high). Anything over 65 and I'm 198+. I rinsed the radiator and trans cooler out with distilled water. The fins all look clear.

Wondering if the serpentine belt might have something to do with it? It's 3 years old, but wondering if maybe it's slipping. It seems plenty tight though.

 

[geanes]

A few thoughts:

• Transmission needs topping after radiator replacement. Will check the ATF level this evening. Thank goodness I have a 98
• New OEM radiator cap with new radiator, always. Yeah, I went CSF based on positive recommendations. I did not transfer any of the foam. I added foam along the topline though.
• OEM thermostat is best and must have jiggle valve position at top. OEM t-stat and o-ring are what I installed. Confirmed jiggle valve at top.
• Are you checking coolant level in radiator after 8 hour cool down (with front of vehicle higher than rear, is best). I'll do this tomorrow morning for sure. Thanks for the reminder.
• Is reservoir hose straight and dropping to bottom of reservoir tank. I see these hung-up on shelve bent, often. Hose is straight with no hang ups.
• Check reservoir hose & cap for obstructions. I've found these plugged! I'll definitely check for obstructions.
• Make sure all three (engine coolant rad, condenser and oil cooler) radiators fins are clean. Rinsed out all 3 several times over the past few months using "spotless" rinse at a local carwash on very low pressure. Considering spraying some of that foaming condenser cleaner in there, letting sit for 20 seconds and rinsing away. Heard very good things about Koil Klean I believe it's called.
• Watch your fuel trims. Short term running lean (-) may indicate vacuum leak or weak or poor fuel injector spray. I've never monitored these. Something I can program into Scangauge I assume. What would I be looking for r.e. "lean" vs "rich"?
• Try spinning fan cold. After a few turns it should loosen up. It can also be stopped with a rolled up newspaper, during warmup. After warm up, as fan clutch gets hot, it will make a loud fan (turbo) sound. Than it can't be stopped by a rolled up paper. With the engine off, I can spin the fan about 1/4 turn before it stops.
• Any change in oil pressure since 260F overheat. Haven't actually checked that other than the useless Toyota gauge in the dash. Nothing abnormal on it though. It sits right in the middle while driving and drops to low at idle just as it always has. I assume the Scangauge has a code I can input to view the oil pressure. Not sure what numbers constitute good vs bad though.

Is coolant level holding? I ask because number one damage from overheating is warped heads. The head gasket than leaks. Coolant level than drops in most cases, but may be very slow to do so. Coolant level seems to be holding fine. When I did the radiator, I had to "top" it off about 3 times over the following days. Once that was done, it seemed to hold the level perfectly fine. I can't find any indications of a coolant leak anywhere. Did an oil change and saw nothing other than oil drain from the pan.

If everything check out. Next would be compression test w/leak down test. Also, overnight coolant system pressure test. That may certainly be in the cards if everything above doesn't check out.

If you get up to Denver stop in.. I can take a look! I will definitely hit you up when I get back up to Denver. I'll bring some gifts from Texas for ya

@2001LC Thanks for the detailed reply. My responses in green above

 

[JunkCrzr89]

What's weird though is that the temps rise with the RPM. If I just idle, I'll sit around 193 (still high). Anything over 65 and I'm 198+.

Symptomatic of water pump possibly not functioning efficiently.

 

[gungriffin]

@2001LC Thanks for the detailed reply. My responses in green above

I would definitely recommend sending the oil out to Blackstone at your next oil change to confirm that there is no coolant in the oil as well. It might not be enough to see with the naked eye. It seems worth the peace of mind to have them confirm that there is none.