Engine temp running hot

Ok guys, I have a 2005 v6 with 163'000 miles on her. Never had this problem before. Or any issues other than u joints and front bearings.
Sitting in traffic for 30 minutes moving about 1/4 mile in Texas 95 degree heat with AC on today. I notice the ac doesn't feel cool any longer. I look down and see my engine temp gauge 3/4 to the red. I turn off the AC and put my windows down. Within a minute the gauge moved back down to the dead middle. This is still higher than normal. My gauge usually reads 3/8 or so.
I had my coolant drained and filled at 100k. I looked tonight and see that there is still some in the overflow.
Any ideas what caused the spike up in temp? Could my thermostat be going? Where does everyone's temp gauge read in their dash? I have a data connector for toyotas. Is there any diagnostics I could get off of there?

Thanks!! Trying to Avoid a breakdown soon!

 

Try some more tests with the a/c on and off.

Best bet would be replacing your thermostat. My never goes above the middle, but if I run the a/c its only for a few minutes.

 

Original water pump?
Original Thermostat?

It could be an issue with either or both if they are original equipment. I've never seen any of my vehicles go over 1/2 way. It could be the humidity and the slow pace in very hot conditions however. A 1/4 mile in 30 minutes is not moving pretty much.

 

Im at 106K and I just replaced my waterpump. Before replacing my waterpump my truck would get warmer than normal on a 30 mile trip. On longer trips with the ac on and more work it would get HOT. I had to roll the windows down turn on the ac etc. Coolant was fine, waterpump wasn't leaking...
I tried repaclacing my waterpump (which looked ok when i took it off) and the thermostat. Total parts was about $160 compared to the 1K the dealer wanted to charge me.
Haven;t had a single overheating issue since. I also invested in an ultraguage to monitor the engine temp, you can learn a lot about your truck that way....

if it keeps happening try down shifting while your driving and it will cool it off. Stay in 4th gear, it helps, trust me.

 

The radiator core might be getting plugged up, if so it's cooling capacity is reduced. I've had similar experiences that you described and it was the radiator.

 

Did the AC get cool when you started moving again? Could be the fan died and no air was moving through the engine causing the truck to overheat and the AC to stop workin'.

 

Pretty much what everybody posted could be the issue. I have a Ultra-gauge and my temp is always at 185*-186.8* and never goes any higher. I have 32000 miles on mine though. I'm assuming that 185 is "normal" operating temp. Arkansas summers are brutal like Texas. 100*+90% humidity makes for a miserable day.

Hope you get it figured out.

 

If that was the case, with no air being pulled over the radiator, wouldn't it completely overheat regardless of the A/C being on?

 

Yes, both original. I was basically standing still with no airflow on a major highway. Thanks for feedback.

 

How did you diagnose this was the case as opposed to something else?

 

Ok, thanks. May give it a go. Hard to downshift when sitting still in traffic.
Was going to take this to the beach in a few weeks. Maybe not now.

 

Keep in mind that we have a clutch, engine-spun fan. When you're sitting still in traffic the fan is spinning, but not enough to really keep the engine cool. While 3/4 up the gauge is a little high I wouldn't be sweating bullets over it. 1/4 mile in 30 minutes is slower than just letting the truck idle forward and the only air getting pulled across the radiator is what the fan pulls. Add A/C to that and it gets worse.

Also, check your coolant level inside of the radiator when the truck is off. If the radiator cap is stuck open, the cooling system won't build enough pressure to keep the boiling point down. Being as it is a 10 dollar, 30 second fix it might be worth your while to change it either way. I usually do on my vehicles at 100k when I do the water pump.

 

Since your A/C was having trouble as well, I'm betting in an airflow issue, either the rad and condensor are plugged up with dirt, bugs..., or your viscous fan hub is dying.

 

Ok, thanks for the replies. Made it to work today with gauge pegged in middle. 88 degrees on way into work. AC worked fine.

Before leaving I removed radiator cap. Fluid was full but it sure was brown. Not pink at all. My overflow reservoir had a little in it as it was sitting at the low level mark. Added some to make it to the high level mark. Also rinsed off the radiator fins with the water hose. The truck started and the fan roared as usual...then slowed to a quiet hum.
I suppose at minimum I need to change my coolant and thermostat. Coolant looked used and abused for sure. Not sure how hard it is to change the water pump while I am draining the fluid. May do that too.

 

looks like this might help http://www.tacomaworld.com/forum/2nd-gen-tacomas/206244-diy-2nd-gen-water-pump-replacement.html
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and I think they changed the coolant on this one http://www.tacomaworld.com/forum/te...intenance-success-water-pump-spark-plugs.html

 

Sounds like time for coolant change, water pump, and thermostat. They're actually not that difficult on our truck, just removing the fan assembly to get to it.

Sounds like the cleansing helped though!

 

This is what you should be looking at, not water pumps and thermostats. At least not yet. What you describe is an airflow issue. When sitting in traffic with the A/C cranked the condenser is HOT. So all that air the fan is pulling through the radiator is also very HOT. So it doesn't have the same cooling effect as even the hot air outside. Some cars have auxiliary cooling fans in front of the radiator that automatically come on when the A/C is turned on to deal with the heat of the condenser. It shouldn't need it because it was designed not to but if you have a condenser or radiator full of bugs and crud and/or a weak fan clutch it's going to get hot.

 

There is an inch or two of space between the condenser and the radiator that is covered up by the fan shroud assembly. Drop the skid plate and take a look up from the under truck into that space to see if there are any obstructions. Last year when I was poking around my truck I discovered a massive amount of leaves, dead grass, and bugs in between my radiator and condenser. I accessed this space by dropping the skid plate and stuck a brush and air compressor up there to clear it out.

It may not be the source of your problem but it couldn't hurt to give it a look.

 

x2.
I would power wash condenser and radiator to keep it clean.
If that does not help take a look at clutch for fan. After you come back from driving, shutdown your truck, open hood, put some gloves and try to spin fan. It should be impossible to spin at full temperature. anything other and you need new fan.

 

You just mentioned in a later post your coolant has changed color. If coolant isn't changed when recommended it can plug up the tubes inside of the core. On some cross flow radiators if the coolant is low it's possible to see some ends of the tubes and see material attached and sticking slightly out of the inside of the tubes. That material is restricting the coolant flow, reduced flow can cause temps to rise just as you described.

I think thermostat is not the likely cause as if it sticks closed the temp is not likely to return to the middle as soon as air starts flowing through the radiator. It's easy to test this out. Turn on your AC and let it idle for awhile duplicating what you did before when the temp went up, to see if the temp again starts going up like in your description. If the temp rises like before I would think it's going to be one of two things, a bad fan clutch as others have suggested or plugged radiator core.

But since you stated your coolant has changed color my money is on a plugged radiator.