Overheating help

Been racking my brain for over a year now on my trucks overheating issue…

When I drive on the freeway or in town with the AC on I don’t really have any issues. It’s when I am at a stop with the vehicle in drive and the AC on (ex. Drive thru)it will start get warmer and warmer. The highest I ever let it go was 233* (making a video for the dealership which was no help. They told me it was normal and tried to sell me a pusher fan). Also it only happens in summer, I live in AZ. AC does stay nice and cold when on.

Here is what I have done… pressure tested the cooling system which turned out to be ok. Replaced thermostat, water pump, fan clutch, radiator, radiator cap(stock cap and trd) and radiator hoses. Also did a coolant flush myself along with the dealership doing one. After no luck I replaced the head gaskets. Found cylinder 6 plug to have a glaze on it. Took heads to machine shop and found that bank 2 head around cylinder 6 was warped .004” (spec is .002”). Had them machined and reinstalled all parts. Now that summer is coming back to AZ my issue is turning back up again.

Has anyone run into this issue before or possibly have more insight. I am already half way bald and this truck is making me loose the rest of it. Ready to throw in the towel and get myself a diesel.

Forgot to mention.. I have a 2015 Tacoma V6 4L.

Thanks for the help in advance!

 

Coolant temperature sensors replaced? Sounds like it doesn't realize it's overheating and that's why it won't turn on the fans when it needs to. Highway speeds won't matter because you're getting enough air flow. There might be a couple of them too, maybe someone with access to the repair manual can chime in.

 

2nd gens have a mechanical fan clutch, it has a built in thermostatic valve that increases fan speed as temperature of the air moving across the fan increases. No electric or electronically controlled fans on 2nd gens.
It's possible although very unlikely the temp sensor is lying but they usually skew to the cooler side, easy enough to check when the truck has been sitting overnight it should read within about 5 degrees of ambient temp.

It's interesting the A/C stays cold, if it was an airflow problem I would expect the A/C performance to be poor at idle.

What happens if you increase engine speed, does it cool off or do you have to be moving?

 

That would be a good idea to check but I have a fan clutch, not electric.

 

I have an ultra gauge which shows me the numerical temp and then once the temp reaches a curtain temp the needle will start to move. I will double check this in the morning though.

it stays cold till about 220* then it will start to gradually get warmer. So if I am sitting in the drive thru and it starts to warm up I can hit the gas to rev up the engine and the temp will start to go down slowly. If I start to drive again it will cool down really fast.

 

Is your fan shroud in place and intact?

 

That's a puzzler..... I assume the fan shroud is in place and undamaged?


EDIT: winkel beat me to the draw, but only by a few seconds.

 

With the engine off does the clutch fan spin freely?

 

Yep, the fan shroud is in place and in perfect condition.

 

Yes, the fan spins freely as it should. I even got a new one just in case the coil in the front was bad but showed no difference.

 

Well, it shouldn't spin too freely.... if it does, it might not engage when it's supposed to. There's temperature-sensitive silicon fluid inside that can sometimes leak out. Some clutch units can be replenished but some are sealed. The fluid is (or used to be) available at Toyota dealers. But you did say you replaced the fan clutch, so that shouldn't be the problem.

 

The original one seemed good but with the situation and everything I had already tried I bought another one from Toyota.

 

That's interesting, has it done it since the truck was new, did it slowly get worse over time, or did it start suddenly?

Driving mine runs from about 178 on a cool day to 197 ish on a very hot day (we regularly see temps over 100F in the summer), idling on a hot day I've seen it get up around 212 or so but usually on those kind of days the A/C is struggling by then too.

 

It did not start this new. It was about two summers ago. I was sitting in the school parking lot waiting to pick up my kids and out of nowhere. I noticed the AC temp was getting warmer. At that point I looked at the ultra gauge and noticed my temperature was about to 210 to 212°. Since then it has been a major issue when temperatures get in the mid 80s or higher. In the winter times I have zero issues with my truck when we get in the streets summer and temperatures reach 115 to 120°. My truck is pretty much not drivable with the Aceon has my temperatures spikes quickly and I do about 202° on the freeway.

 

Interesting, overheating problems at idle and low speed are typically due to poor airflow or coolant circulation but you say you have replaced everything.

I'm assuming there are no blockages in the front of the truck and the grill area and the condenser fins are clean?

There was a TSB for 15s for poor A/C performance in high ambient temps, the fix was to add an electric fan but the bulletin doesn't mention anything about the engine potentially overheating.

 

How's your coolant mix? It should be approximately 50/50, water/coolant.

 

I believe the 3rd gens have a kit available as well. Weird though if it worked just fine for the first 6-7 years and just stopped working recently. At this point what's there to lose though.

 

Maybe its not right thermostat? Or its installed backwards maybe?

 

there are no blockages, I hosed out the condenser fins when I was installing the new radiator. Can see light on the other side of the condenser.

That’s the TSB that the dealership tried to sell me on ( like $3k). I told them no that there was some other issue as this started out of now where. The truck would do great in the summers until something changed.

 

The coolant mix is straight from Toyota premixed.