Overheating issue

Hi all. I thought I’d ask here (in addition to Cdn local FB group), as I’m having an overheating issue at low speeds when running my a/c. It’s 2022 with 18K kms (11K miles). Local temp is 24°C / 75.2°F. I have a C4 bumper with a lightbar, and a winch. Radiator is cleaned, hosed off any debris before this started occurring. I have no leaks, and fluids are from factory since low mileage. Oil changed every 5K kms / 3.1K miles. Using a scan tool, temps sit about 208°F until a/c is used, or if I sit idle and slowly starts to climb … and I turn a/c off at 225°F. 2 days ago I had to pull over as noted by dashboard message initially saying engine, then saying trans fluid. But I’m assuming the engine coolant is heating up the trans via the radiator. Difficult for any warranty work since I’ve modded bumper. Someone suggested to add an electric fan to front of radiator as it’s a heat soak issue (poor airflow) vs transmission overheating. I’m looking to see if others have had an experience like this and found something else creating issues. I’ve had my current set up since Aug 2023, but only had issues showing up this April.

 

Maybe a defective thermostat ?

 

Yeah, either thermostat or maybe your fan clutch is faulty or worn out and isn't fully locking up at operating temperatures? To check for the latter condition, get your runner up to operating temp, then kill the engine and try to spin the fan blades. If it's difficult or impossible to spin move the fan blades, the fan clutch is working as it should. When the engine is cold, they should spin somewhat easily...but if they're still doing that when the engine is hot, the clutch is shot.

Just a thought.

TimG.

 

Agree to both posts above. Under warranty, let toyota diagnose and pay to repace Thermostat and or fan clutch.

 

I wouldn’t think it’s the bumper causing it, but you may want to consider it. Do you have a winch? How close is it to the radiatior, and how large is it? Does maybe it’s blocking flow too much.

You may want to remove the LED lights to see if the increase airflow reduces temps.

Before any of that, check your radiator coolant level at the radiator cap when it’s cold. Make sure it’s all the way up to the neck. Sometimes air bubbles cause poor heat flow. And agree, check the fan too.

 

I have the c4 and think it actually increases air flow from stock bumper. Can't really see it in OP's pic, but there are big openings both sides at the bottom to reach winch.

 

Compared to the stock bumper, I think you are correct.

 

New input from a FB post. I didn’t realize that the a/c radiator is directly in front of the engine coolant / trans radiator, and there is a small gap in-between. There could be dried mud or debris in there so going to tackle that tomorrow and see how it goes. I feel dumb not realizing how the a/c was routed or even works

 

Don’t know if this is related but our Chevy Tahoe with 12k miles overheated one day while driving down the highway. Temp gage pegged into the red . The dealership just happened to be 2 blocks away . They said it was a bad radiator cap. New cap and we were on our way . Never overheated again.
Worth a try.

 

That’s ok, we all learn something new everyday. Count it as experience. Check for the mud and let us know if this was your issue.
Never heard of that happening, but ….

 

As you said check for mud. If that’s not it, then warranty time.

 

It’s worth the OP try to find the problem first.

Warranty will be an uphill battle. And it will probably take at least a couple of visits with $180 diagnostic fees each for them to blame the bumper without any actual exploration of the problem.

Blaming the bumper may not be correct, but it’s reasonable to suspect it. When I installed mine, I had to cut sections off of some plastic baffling intended to contain and direct airflow. The winch also sits right in front of the radiator. Both are reasons for the dealer to “reasonably” charge you 180 bucks for a diagnosis of “it’s the bumper”.

 

Which is why I never do any mods that will affect anything in the engine compartment that is still under factory warranty. These dealers will try to blame you for anything to get out of warranty repairs.

 

Maybe time to take a poll on members that have the same style bumper as you.

Example:
“C4 bumper owner please vote, please input if you have any engine temp increase or not after install”

 

Could remove the bumper and winch and drive it around to see if the coolant temperature is lower. That would prove or disprove the theory.

 

Hi all. Thx for all the advice. Issue almost 100% resolved. As I noted above, I worked to clean between the the 2 radiators … the engine rad and the a/c rad, as there is a very small gap between them. I had previously driven through some deep muddy puddles in late October. I obviously didn’t clean it out properly (or at all), and from the results looks like there was some caked on mud that has been reducing air flow. I had used some warm, soapy water, and slowly poured it into the gap. I also used a soft bristle brush to help agitate. The held the top gasket (a spongy gasket fills the top gap of about 1/2”), and used only house hose pressure to rinse it off. Afterwards I realized there is a gap on the bottom where we can spray in there. But in that attached image, you can see the small gap between the radiators. It is not an easy accessible space to clean.

 

That must be a dramatic re-enactment. Your hands are too clean.

 

From the mud splashed on your hoses, I could see where you definitely could have mud in your radiator fins.

 

Ha ha ha … no. I had gloves on the first time around (when I did the soapy water), and then used the brush again when rinsing only. Took the gloves off to use the phone.

 

i dont think its the bumper causing the issue as I have a SSO bumper similiar to yours and never had an issue in hot summer weather crawing in traffic. Temp gauge never goes above 1/2 even when it was 95 out crawing on I95. Maybe a thermostat issue?

 

I would trade that POS in ASAP?

 

I agree after reviewing everything. The C4 bumper is better for air vs the stock bumper, even with the lightbar and winch.

 

For a 1996 SR5?

 

Have you a final decision on what is the root cause of your temp issues as of yet?

We Need To Know!

 

This thread is a good reminder to clean your radiator after visiting a few mud holes xD

Thanks OP

 

OP - I hope hosing down the area resolved your issue. Let us know.

FYI. I have the same setup minus the winch. Installed exactly a year ago.

I don’t tow or wheel in mud. 50/50 highway and city driving in mostly flat roads. While not overly heavy on the throttle, the water temperature always hover around mid 180s to a couple clicks over 190 for a brief moment in hot days according to my scan gauge ii. Factory coolant and original rad cap.

 

Haven’t had the chance to take to the service department (due to being an hour away, and busy till mid July). While truck has been acting normal now (since thoroughly cleaning the radiators), there was one incident on the weekend where it temp creeped up over halfway. The circumstances occurred when I drove while running the a/c, then turned parked (turned off, went in store) for 2-3 mins (ambient temp outside was 27°C), then sat about 3 mins after with truck running and air (while on the phone), and then drove off but stuck in traffic. Before I left the parking lot, the temp was already starting to climb over halfway. So there is something related to the a/c heating up the engine bay and issues with it trying to dissipate that heat. I haven’t really seen anyone else with this issue, so there must be something specific to mine that isn’t working properly. Hopefully it is something easy to diagnose and resolve by the service department.

My vehicle is a 2022 (new July ‘22), has 18,800 kms (11,681 miles), intake air filter is clean (factory original, very little dust), except oil … all fluids are original factory and levels perfect, and my oil changed every 5,000 Kms (on the 5K, except first one at 1,600 Kms). I’ll change the oil again soon since it’s coming up to 5 months since my last one. Tires are Toyo AT3s C load 285/70s on TRD Pro rims, that have been on since April 2023, rotation with spare as well every 5K kms. I drive the truck in a way to get good fuel economy, with the exception of merging safely on hwy or passing.

 

My gauge does not budge even at 110F here in PHX. If you notice a reduction in A/C performance when the gauge starts to climb, it is most likely a weak radiator fan clutch.

 

I know it sounds ludicrous but I'm thinking water pump. For troubleshooting purposes, I would borrow / get an infrared thermometer and measure on the water pump and see what you get. You might even be able to watch the temperature climb this way if it is the water pump.

 

Did you ever find your solution? I haven't solved mine yet; my problem is eerily similar to your description, and it's been almost two years since it began. It's so intermittent that I haven't been obsessively chasing it down, but it began in July '23. I replaced the fan clutch in '24 but it still happened afterward. Now, going into '25, I'm planning to replace the radiator cap, thermostat, and water pump, then wait for summer to roll around and see if it keeps running hot. My thread here: https://www.4runners.com/threads/sporadic-overheating-issue-solution-ongoing.32462/