2005 Tacoma overheating after freeway driving 75 mph+

Hey Y'all
New member here, looking for advice.
2005 Taco Prerunner TRD Sport 4.0L 249000 miles.
All scenarios are with A/C on, in Phoenix AZ. Temps at 102-118

I've replaced the thermostat, and done a coolant flush.

So here's the deal.....

I can start the truck and let it idle for an hour with no issues.

I can drive the truck around town for 2 hours, stop and go, max 55mph and not have an issue.

I found out this afternoon that I can cruise on the freeway for an hour at 60-65, and have no issues.

This is where I'm confused, and the trouble starts.......

If I drive 70-80 mph for 30 or more miles, the minute I get off the freeway and idle for any amount of time, the temp gauge goes into the red.....

As soon as I'm moving again, or put my truck in neutral & rev the engine, it will cool down.

When it starts overheating at stoplights, etc, it will not quit until I park it and let it cool completely.
And then, I can start it and run around town like there is no problem......

Thoughts???

Thank you in advance Tacoma Peeps!

 

Definitely the Radiator fan clutch, when your engine gets hot the fan clutch engages and allows the fan to spin with the engine, when it's cool the clutch disengages. When they go bad you will get symptoms like what you described, when you're on the highway the fan isn't needed since you have plenty of air moving through the radiator as opposed to sitting in traffic.

Edit: If you get in a pinch to where you can't turn your engine off, blast your heater on high it should buy you some time until you can get pulled over or back on the highway.

 

^^^^^^

 

My confusion is....why is it okay sitting in traffic, until I've been on the freeway for 30 miles?

 

Your radiator has a small cooler built inside that keeps your transmission cool, so when your trans heats up to operating temp (freeway drive) it adds more heat to your radiator and if the fan doesn't work your engine and trans will quickly overheat. It also takes a little while for the trans to come up to operating temp.

 

Thanks Pab,
That makes sense.... I'll let y'all know how it works out.
Thanks again!

 

Anytime!

 

My truck has almost the same exact problem. I was wondering if adding an external Transmission cooler in-line with the one already in my radiator (I have a '05 DBLCBLB 4x4) would help the overheating issue too? Additionally I have an intermittent P0430 code and from that I am surmising that maybe a clogged Catalytic converter would cause the engine to overheat as well. Could this be the case?

-Thanks

 

If your engine is overheating, a trans cooler will not fix your problem. If your trans is overheating then it would. A p0430 will not cause an overheating issue. Check basics
Coolant level
Radiator fin cleanliness
Radiator fan operation
Verify thermostat operation

 

I replaced the following items already (July '18):

-Water pump
-Radiator
-Fan Clutch
-Upper and lower cooling hoses
-Serpentine belt
-Thermostat
-Idler pulleys
-Added premixed Toyota Coolant

And here is my reasoning why I think the P0430 code might cause overheating --> back pressure from a clogged Cat not allowing the hot exhaust gases to escape.

And as far as adding the external transmission cooler goes... my engine overheating problem doesn't happen until I get into crawling (less than 5mph) traffic conditions after being at highway speeds of 65mph for over an hour. I think that once the transmission gets up to temperature that the trans-cooler built into the radiator doesn't allow it to dissipate the heat quick enough.

Thoughts?

 

As I said above a p0430 will not cause an engine overheat. P0430 means the cat is not doing it’s job by removing harmful gases before the exhaust enters the atmosphere. If the cat was truly clogged your engine would run like shit. You probably won’t be able to rev past 2000rpm. Is the system bled completely? Did you burp the heater core? Have you verified the fan clutch is pulling air through? Just because the fan spins doesn’t mean it’s working. I’ve got bad fan clutches before right out of the box.

 

Once everything is all up to temp, if you can stop the fan with your hand, the fan clutch is shot. I'm not responsible for you sticking your hand in the fan, even though I've done it. Someone here once suggested trying to stop the fan with a rolled up newspaper. Probably a safer way to do it, if you can find a newspaper now days.

 

Newspaper? What’s that?

 

Keep in mind that when you overheat your engine , you also overheat your transmission .
https://www.tacomaworld.com/threads/transmission-coolers.526283/

 

How do I burp the heater core? I replaced the entirety of the cooling system back in July and have driven 3000+ miles since then. I find it difficult to believe that there still could be air in my cooling system?

Have I verified that the fan clutch is pulling air? How do I accomplish this?

My Taco only exhibits this overheat condition after an hour plus of freeway driving and then only in bumper to bumper traffic less than 5mph otherwise according to my ODBII port gauge which reports the coolant temperature digitally my truck hovers between 186F - 194F. When I encounter traffic in the scenario listed above it starts to climb above 194F and gets as high as 208F before it really starts to takeoff.

I have about 191,000 miles on my truck with no major engine problems and regular oil and filter changes.

 

Maybe the dreaded bad head gasket issue on 2005-06 Tacoma's.