High Coolant Temps

[4x4mike]

I've got an '07, V8, 4wd, 275's, ~122k miles that's been running warm for the past year or so. Hasn't bothered me much until now as we're having daily highs over 100* (about 13 days so far).

I've got an Ultra Gauge plugged in all the time and the coolant temps will get to 204-206 with stop and go driving. I get the same results with a blue tooth OBD reader. It's seemed to do this for the past year, even in the Winter. I've got full heat and AC and the needle stays in the middle of the gauge. I have not over heated.

I had the TB, WP and 180* T-stat replaced a few years ago and until I plugged the UG I didn't know I was running that hot. I feel it should be lower so I thought I'd ask here.

Driving on the freeway doesn't seem to lower the temps much except when I take it out of over drive and have the rpms increase. At that time it might go from, say 204 to 200 and stay there. In stop and go, summer driving I can hear and feel the mechanical fan engage, especially after idling at a stop light.

So, doesn't over heat (or fluctuate that much) so I'm not thinking it's the t-stat. I can hear and feel the drag from the fan. It also has resistance when the engine is hot and I turn it by hand so I'm thinking the clutch is fine. The radiator and condenser are also clean (not packed with mud, bugs or debris).

FWIW, an IR temp gun is showing 185-195 at the metal t-stat housing when the engine is warm (say 204 on the UG), and 195-200 on the metal housing where the upper radiator hose goes into the top of the engine.

Should I consider changing any of the above parts? What about the temperature sensor? I'm not getting any codes and I don't have an electronic fan so I can't say the sensor is malfunctioning.

System has Toyota pink in it. Level has been full since I had the TB work done a few years ago. No leaks, over flow is at the mid line.

Kind of scratching my head and hoped someone could give me some insight or help me cross some items off my list.

 

[Buckaroo]

I've got an '07, V8, 4wd, 275's, ~122k miles that's been running warm for the past year or so. Hasn't bothered me much until now as we're having daily highs over 100* (about 13 days so far).

I've got an Ultra Gauge plugged in all the time and the coolant temps will get to 204-206 with stop and go driving. I get the same results with a blue tooth OBD reader. It's seemed to do this for the past year, even in the Winter. I've got full heat and AC and the needle stays in the middle of the gauge. I have not over heated.

I had the TB, WP and 180* T-stat replaced a few years ago and until I plugged the UG I didn't know I was running that hot. I feel it should be lower so I thought I'd ask here.

Driving on the freeway doesn't seem to lower the temps much except when I take it out of over drive and have the rpms increase. At that time it might go from, say 204 to 200 and stay there. In stop and go, summer driving I can hear and feel the mechanical fan engage, especially after idling at a stop light.

So, doesn't over heat (or fluctuate that much) so I'm not thinking it's the t-stat. I can hear and feel the drag from the fan. It also has resistance when the engine is hot and I turn it by hand so I'm thinking the clutch is fine. The radiator and condenser are also clean (not packed with mud, bugs or debris).

FWIW, an IR temp gun is showing 185-195 at the metal t-stat housing when the engine is warm (say 204 on the UG), and 195-200 on the metal housing where the upper radiator hose goes into the top of the engine.

Should I consider changing any of the above parts? What about the temperature sensor? I'm not getting any codes and I don't have an electronic fan so I can't say the sensor is malfunctioning.

System has Toyota pink in it. Level has been full since I had the TB work done a few years ago. No leaks, over flow is at the mid line.

Kind of scratching my head and hoped someone could give me some insight or help me cross some items off my list.

I would pull that thermostat, put it in a pot of water on the stove and see at what temp it fully opens - if it is a 180F thermostat, it ought to be 180F. The other potential issue that you should consider is a restriction in your coolant system...like maybe a partial blockage in the radiator. You could use your temp gun at different points on the face of the radiator and look for a temperature differential.

 

[rdruss]

I would check the IR gun on boiling water and see if accurate. If it is then it's telling you the engine not as hot as gauges indicate. Checking the stat will tell you if it is performing as it should, but that's only to let the engine coolant start to flow to radiator, fully up to temp your coolant should be in the 190-200 range depending on load and ambient.

 

[4r-4ever]

when was the last time these were replaced?
radiator

fan clutch (based on your info when it's out of overdrive, the temp lowers). it seems this fan clutch is no longer doing its job.

coolant

 

[4x4mike]

I would pull that thermostat, put it in a pot of water on the stove and see at what temp it fully opens - if it is a 180F thermostat, it ought to be 180F. The other potential issue that you should consider is a restriction in your coolant system...like maybe a partial blockage in the radiator. You could use your temp gun at different points on the face of the radiator and look for a temperature differential.

I ordered a new thermostat so when I pull the old one I'll just replace it. Blockage is something I'm not sure about though so I'll have to look into that. I'll shoot the radiator as well but so far as I could tell the temps coming out of the top and bottom hose were consistent with cooling but unsure about a blockage.

 

[4x4mike]

I would check the IR gun on boiling water and see if accurate. If it is then it's telling you the engine not as hot as gauges indicate. Checking the stat will tell you if it is performing as it should, but that's only to let the engine coolant start to flow to radiator, fully up to temp your coolant should be in the 190-200 range depending on load and ambient.

I haven't checked my meter with boiling water but that sounds like a good idea. I've been using two OBD devices and they read identical and I'm assuming that reading comes from the coolant temp sensor. The dash gauge sits right in the middle all the time but the elevated OBD temps are what have me concerned. I've read a bubble in the system could make the sensor read incorrectly so I'll burp the system when I change the t-stat.

 

[4x4mike]

when was the last time these were replaced?
radiator

fan clutch (based on your info when it's out of overdrive, the temp lowers). it seems this fan clutch is no longer doing its job.

coolant

Radiator is likely factory. The coolant and t-stat are 3-4 years old. I ordered a new clutch and t-stat after thinking about all of this so hopefully that will give me some better numbers.

 

[BlackWorksInc]

Sounds fine to me?

FSM states for an '07 2UZ-FE it should be: 80 to 100°C (176 to 212°F): After warming up. Most vehicles operating around to slightly above boiling temperature, which is why they're pressurized systems, our caps are rated for a minimum opening pressure of 80kpa or just under 12psi. The thermostat should start opening near it's rated temperature of 82°C (the FSM states it should begin opening around 80 to 84°C/176 to 183°F) and should be about 8mm or more (basically fully open) at 95°C/203°F and fully closed below 40°C/104°F.

Toyota's specified boiling over temp for SLLC is 108°C (about 226°F). Keep in mind that for a 50/50 glycol coolant you gain about 3psi for every 1°F of temperature; so at 11.6psi/80kpa over atmosphere you're looking at an increase of boiling over protection of roughly 34.8°F/19.1°C additional. So I would say you're well within the tolerances Toyota accounted for and I wouldn't be too worried, also IR thermometers can have a variance in measurements based on the material's reflectivity (excessive or lack thereof), composition, distance of the thermometer to the measurement site, as well as some other factors from what the owner's manual for my Snap-On one I bought years ago and my experience has shown; basically don't quibble over a few degrees difference between measurement tools here.

The most accurate tool to measure your coolant temp on your vehicle is going to theoretically be the actual ECT sensor. The reason I say theoretically is because it too has a tolerance for accuracy (it's probably something like ±1°F or something, I have never really looked at their specifications to be honestly, again these aren't lab grade sensors), plus a theoretical resistance of .01Ω or less for the signal integrity to the ECM. It is possible to get corrosion/gunk on the ECT and that could affect the sensor reading, but the only time I have ever seen that was with an engine that was just filled with stop leak gumming up everything.

TL;DR-
You're overthinking it, vehicle is operating as designed. Maybe check the A/C Condenser and Radiator fins for debris/crap in between then and verify your mechanical fan clutch is engaging properly; probably would not hurt to make sure the radiator cap is working good too. But beyond that I wouldn't worry about it.

 

[4x4mike]

Sounds fine to me?

FSM states for an '07 2UZ-FE it should be: 80 to 100°C (176 to 212°F): After warming up. Most vehicles operating around to slightly above boiling temperature, which is why they're pressurized systems, our caps are rated for a minimum opening pressure of 80kpa or just under 12psi. The thermostat should start opening near it's rated temperature of 82°C (the FSM states it should begin opening around 80 to 84°C/176 to 183°F) and should be about 8mm or more (basically fully open) at 95°C/203°F and fully closed below 40°C/104°F.

Toyota's specified boiling over temp for SLLC is 108°C (about 226°F). Keep in mind that for a 50/50 glycol coolant you gain about 3psi for every 1°F of temperature; so at 11.6psi/80kpa over atmosphere you're looking at an increase of boiling over protection of roughly 34.8°F/19.1°C additional. So I would say you're well within the tolerances Toyota accounted for and I wouldn't be too worried, also IR thermometers can have a variance in measurements based on the material's reflectivity (excessive or lack thereof), composition, distance of the thermometer to the measurement site, as well as some other factors from what the owner's manual for my Snap-On one I bought years ago and my experience has shown; basically don't quibble over a few degrees difference between measurement tools here.

The most accurate tool to measure your coolant temp on your vehicle is going to theoretically be the actual ECT sensor. The reason I say theoretically is because it too has a tolerance for accuracy (it's probably something like ±1°F or something, I have never really looked at their specifications to be honestly, again these aren't lab grade sensors), plus a theoretical resistance of .01Ω or less for the signal integrity to the ECM. It is possible to get corrosion/gunk on the ECT and that could affect the sensor reading, but the only time I have ever seen that was with an engine that was just filled with stop leak gumming up everything.

TL;DR-
You're overthinking it, vehicle is operating as designed. Maybe check the A/C Condenser and Radiator fins for debris/crap in between then and verify your mechanical fan clutch is engaging properly; probably would not hurt to make sure the radiator cap is working good too. But beyond that I wouldn't worry about it.

Thanks for the info, very informative. I've been told not to chase 10* but at the same time I don't want to over heat the engine especially driving in the mountains or offroad.

At 122k miles, I figure it's time to put some PM parts on for good measure. It's been pretty warm here for sometime so I've been looking at those temps and hoping to not strain the system. In searching it seems guys have much lower running temps but it's likely all in the details. Your explanation gives me some piece of mind.

I replaced the radiator cap as PM before a trip two years ago. I had seen multiple pics online of broken ones and I was unsure of it's age. A clutch should be here this week and I shoot water backwards through the radiator every 6 months or so just to keep things clean.

Thanks again.

 

[phatcheeks]

Sounds fine to me?

FSM states for an '07 2UZ-FE it should be: 80 to 100°C (176 to 212°F): After warming up. Most vehicles operating around to slightly above boiling temperature, which is why they're pressurized systems, our caps are rated for a minimum opening pressure of 80kpa or just under 12psi. The thermostat should start opening near it's rated temperature of 82°C (the FSM states it should begin opening around 80 to 84°C/176 to 183°F) and should be about 8mm or more (basically fully open) at 95°C/203°F and fully closed below 40°C/104°F.

Toyota's specified boiling over temp for SLLC is 108°C (about 226°F). Keep in mind that for a 50/50 glycol coolant you gain about 3psi for every 1°F of temperature; so at 11.6psi/80kpa over atmosphere you're looking at an increase of boiling over protection of roughly 34.8°F/19.1°C additional. So I would say you're well within the tolerances Toyota accounted for and I wouldn't be too worried, also IR thermometers can have a variance in measurements based on the material's reflectivity (excessive or lack thereof), composition, distance of the thermometer to the measurement site, as well as some other factors from what the owner's manual for my Snap-On one I bought years ago and my experience has shown; basically don't quibble over a few degrees difference between measurement tools here.

The most accurate tool to measure your coolant temp on your vehicle is going to theoretically be the actual ECT sensor. The reason I say theoretically is because it too has a tolerance for accuracy (it's probably something like ±1°F or something, I have never really looked at their specifications to be honestly, again these aren't lab grade sensors), plus a theoretical resistance of .01Ω or less for the signal integrity to the ECM. It is possible to get corrosion/gunk on the ECT and that could affect the sensor reading, but the only time I have ever seen that was with an engine that was just filled with stop leak gumming up everything.

TL;DR-
You're overthinking it, vehicle is operating as designed. Maybe check the A/C Condenser and Radiator fins for debris/crap in between then and verify your mechanical fan clutch is engaging properly; probably would not hurt to make sure the radiator cap is working good too. But beyond that I wouldn't worry about it.

Kind of unrelated. Where in the FSM is the coolant temps located? I have an 04 v6 but cant seem the find the temp info anywhere. Its a downloaded FSM so it might be missing a few things.

 

[BlackWorksInc]

Thanks for the info, very informative. I've been told not to chase 10* but at the same time I don't want to over heat the engine especially driving in the mountains or offroad.

At 122k miles, I figure it's time to put some PM parts on for good measure. It's been pretty warm here for sometime so I've been looking at those temps and hoping to not strain the system. In searching it seems guys have much lower running temps but it's likely all in the details. Your explanation gives me some piece of mind.

I replaced the radiator cap as PM before a trip two years ago. I had seen multiple pics online of broken ones and I was unsure of it's age. A clutch should be here this week and I shoot water backwards through the radiator every 6 months or so just to keep things clean.

Thanks again.

If you're hitting/going over sustained temperatures of 100°C/212°F That is probably where I'd start getting a bit nervous and concerned in regards to touching on overheating concerns. But more importantly you'd also want to see your oil temps for the engine and transmission, as those could get hotter than the coolant faster and start to cook.

Kind of unrelated. Where in the FSM is the coolant temps located? I have an 04 v6 but cant seem the find the temp info anywhere. Its a downloaded FSM so it might be missing a few things.

For the operating temperatures, I pulled that from the ECM Data List section for the applicable engine option. This is a section in the FSM will list each Data List item that you can see on the factory scantool, roughly what it does, what it's min/max range is, and what it should ideally be at.

For the Thermostat numbers I pulled that from the "Inspection" sub-heading for Thermostat under 2UZ-FE Cooling. Some of these specifications are spread out in obscure parts of the FSM, it should really be in the Service Data section; but that doesn't always have every little bit of information so you have to hunt around.

 

[NCHornet]

I didn't have time to read the whole thread but judging what you wrote in your first post it sounds like somebody put the wrong stat in being that your temps are fairly stable. I have owned a half dozen Yota's of various kinds and every single one never got the temp gauge to even go half way. If it ever did it meant I had an issue I needed to look into. YMMV?
NCH

 

[4r-4ever]

[MENTION=22406]4x4mike[/MENTION] did you fix this yet?

 

[4x4mike]

[MENTION=22406]4x4mike[/MENTION] did you fix this yet?

I installed a new factory thermostat and fan clutch and it seemed to do the trick. In hot stop and go traffic the highest coolant temp I've seen is 196 (at a stop) and it quickly drops to 194 and holds between there and 192.

On the bench, the new fan clutch felt the same as the old as far as resistance at room temp. The old clutch didn't leak and I'm thinking it is/was fine but because I had already ordered one and had the old one out I changed it. At cold start up you can tell it's much more engaged due to the quick roar but by hand it felt the same.

I'm thinking the culprit was the thermostat. The shop that did the TB and WP put a Motorad (Stant) 180* unit in there and I'm thinking it wasn't up to the job. It's possible it's always functioned as it was but I didn't notice until the Ultra Gage. BlackWorksInc let me know the engine was still within spec as far as temps go but it was a little high for my liking.

 

[4r-4ever]

good to know. i would think it's the fan clutch. that's what controls the flow of air there when the engine is hot and especially when the car is parked idling.

thanks for the update though but who knows until you swap the fan clutch quickly to find out.

I installed a new factory thermostat and fan clutch and it seemed to do the trick. In hot stop and go traffic the highest coolant temp I've seen is 196 (at a stop) and it quickly drops to 194 and holds between there and 192.

On the bench, the new fan clutch felt the same as the old as far as resistance at room temp. The old clutch didn't leak and I'm thinking it is/was fine but because I had already ordered one and had the old one out I changed it. At cold start up you can tell it's much more engaged due to the quick roar but by hand it felt the same.

I'm thinking the culprit was the thermostat. The shop that did the TB and WP put a Motorad (Stant) 180* unit in there and I'm thinking it wasn't up to the job. It's possible it's always functioned as it was but I didn't notice until the Ultra Gage. BlackWorksInc let me know the engine was still within spec as far as temps go but it was a little high for my liking.