2006 4.7 Tundra overheating

Guys, I am stumped. I’ve got a issue with my truck overheating, and I believe it to be due to the fan not working properly. As the temperature rises, I can either shift to neutral or go into park and increase the RPM’s (which causes the fan to spin faster) and then it will start to cool down.
The issue is, I don’t know how to fix this. Over the past couple of months, I have replaced the water pump, radiator, radiator cap, fan clutch, thermostat, and coolant temperature sensor. I’ve run out of things to change, but I am still having this issue. Any advice is greatly appreciated!

 

Have you burped the coolant in the radiator loop?

 

I have not….at least that I know of. Can you describe how to do that?

 

If your fan isn’t spinning normally, it could be the fan clutch going out I suppose.

 

He says he replaced it.

Burping the coolant? Here's a quick How to:

1. Top off coolant with the engine cold.
2. Turn on your Cabs Heat to allow coolant into the heater core. The blower motor does not have to be on.
3. Allow the engine to come up to temperature. This should open the thermostat.
4. The coolant level should start dropping.
5. Allow the engine to cool before you top off the coolant a final time.

Fellas, did I miss anything?

Also, @Fisher1780 what brand of parts did you go with that you have replaced?

If they are mismatch brands, please list each brand with each part.

 

So the fan clutch was today, and it was a Duralast. Thermostat was a Failsafe. Water pump was OEM. I do not recall what brand the radiator was, but it was purchased at O’Reilly’s.

 

Did you put the fan shroud back on, as well as the clip on piece?

If yes, I'd say try getting a denso fan clutch and t-stat.

If radiator is not denso or koyo, it may be too thin of a core. If it doesn't measure over 1" thick. Many aftermarket are 5/8" and too thin.

 

Can shroud was put back in place after radiator was changed out. Radiator was a Murray Heat transfer. It’s 1 1/4” thick.

Discovered something new while burping the system. I turned the heater on so that it would cycle through the heater core, but it still blew cold air inside. Never warmed up. Could these issues be related?

 

So, stupid question here, but ... have you hooked up an OBDII scanner that can show you what temperature the ECU is seeing?

As @Tundra2 provided great pictures of for another user in the last day or so, the 2UZ has two temperature sensors, one for the dash gauge, another for the ECU. You already see what your dash gauge is seeing, is the ECU seeing the same thing from its sensor?

I'm having a hard time trying to fathom what else could be wrong after all the stuff you replaced, unless, like, the heads/block are jammed up because you used the wrong coolant (i.e. you need to use red, others can corrode), or at some point you mixed different colors of coolant which is a huge no-no (can react/clog), maybe you didn't clock the thermostat correctly, or like Noah said, air bubbles jamming up the works.

I mention t-stat clocking because, if your old t-stat was bad, and you didn't clock the new one right, you'd still have an issue there. The other things (coolant related) would be something which existed before, and therefore would exist after. Temp gauge is just one of those "oh shit, I wouldn't have expected that!" things.

 

Yes or no.

This could indicate you have blockage, which would prevent coolant from circulating. Which then ties me back to my previous message, which I started typing after you replied.

 

So after running it for a while, the heater hose that feeds to the heater control valve was hot. The hose on the other side of the valve was cold. So I took the hose loose from the control valve to make sure it was functioning properly. It was. Put it back together, started it up again, and all of a sudden the heater starts working again.

So maybe it had some kind of vapor lock that corrected itself once it was able to be bled?

For the coolant, I can’t be sure that nothing different has ever been put in besides purple, because this truck is on teenager #2, and hasn’t been my daily driver for 5 years. IF there was a different coolant added at some point, would the best thing be to take it somewhere for a complete flush and fill?

 

Here is that picture.


The small, gray sensor is for the instrument cluster. The green connector is for the ECU.

The later model 2UZs might be different, but I doubt it.

 

Wait, is the jiggle valve oriented correctly?

 

Jiggle valve is due north, straight at the top.

For the sensors, I replaced the ECU sensor today, but I have not done the other smaller one. After that was replaced, when the engine was hot, the fan clutch seemed to shift into a gear that it had not previously found. Made me think that maybe the sensor was the magic fix. But, after putting it on the road for 10 minutes, temp started to keep back up. That’s when a shifted to neutral and revved the engine a few times to get that fan spinning faster, and it began to cool down to a normal temp.

 

My gut says you need a denso radiator.

What brand temp sensor? OEM is best.

Check to make sure this part number is correct for your truck.

 

Radiator is thick enough then.

Pick up some Valvoline Asian vehicle coolant (hoat) and DIY it. Remember to open the block drains on both sides too.

I'd say try a different thermostat first. Denso.

 

I didn’t have any issues when I did my Timing Belt.

I just parked the truck facing up hill filled the best I could, had the engine running, heater on, with the cap off the radiator and slowly poured coolant in till it stopped taken it.

Did the same process on the Sequoia, didn’t open any.

Side note, my Jiggle Valve is short and tilted facing down to the left. The Tundra’s is always pointed north.

 

If you still need to burp the coolant, do what Noah said, and add this in there. It's almost like cheating.

$20 JEGS 51220 No Spill Coolant Filling Funnel Kit Prevents Spills & Trapped Air

https://www.amazon.com/JEGS-Coolant...cint=&hvlocphy=&hvtargid=pla-4584482474267180

 

Yeah, I really need to purchase one of those. Tried to do it with a homemade version, and it did not work out the best.

 

Could be ...

Red. Needs to have red in it. If not using Toyota's red, Zerex "Asian" red is a good substitute, it'll say Toyo/Lex clearly on the front of the jug.

 

Well….the kid drove it to school this morning and reported no issues. Temp never got above the mid-point on the gauge. I’m not optimistic enough to believe that it is fixed and won’t return, but at this point a win is a win.

 

[QUOTE="shifty`, post: 2939140, member: 48239"



Red. Needs to have red in it. If not using Toyota's red, Zerex "Asian" red is a good substitute, it'll say Toyo/Lex clearly on the front of the jug.[/QUOTE]

In your opinion, since it has all purple in there now, should I flush and fill with red? Or let it ride for the time being?

 

Jumping in at the end, a pressure test might be useful (to preclude any leaks), and a new OEM radiator cap is a good investment.

 

Purple is not compatible with Toyota and Honda. Something I learned with my Hondas a while back.

Red coolant is silicate and borate free, both of these are abrasives. Silicates, and potentially borate, will eventually cause non-magnetic precipitates (maybe magnetic too?), which can clog passages. Being abrasive, they can can wear out seals and gaskets over time. If it was me, *I* wouldn't personally run purple in a Toyota or Honda. If you wanted to drain and go to Toyota red (or pink, it's long life, but Zerex red works), I'd drain, then run a couple of water cycle flushes (with heater on) to dilute any purple left in there, before adding red. And use a kit like what @bmf4069 shows when re-filling. Running the water cycles will take longer, but save you from opening block plugs, and even if opening block plugs you should run a cycle of water.

Silicates are great for protecting aluminum, and with red coolant not having any, you'll typically find phosphates to coat and protect internals as compensation.

If you've been using purple this truck's whole life - I think purple is for German/Euro brands, IIRC? - I'd consider doing a proper flush. I like the little bottles of Prestone radiator flush. You can get 6 packs on scAmazon. It's about the only thing I'd buy from scAmazon with how rampant counterfeit parts are on there these days.

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Get rid of the stock fan and get a flex a lite electric fan . They have made one that is for your tundra set up. Call them and talk to them

 

First of all, GREAT info. I appreciate the education and knowledge of others.
Second, I must be burnt out from working on this thing, because I didn’t use purple. I in fact did use red/pink from PEAK.

 

I’ve thought hard about doing this, but I’ve read from several guys about it being a bad decision. So I’m kind of torn about whether or not I should do it.

 

Good deal! Yeah, purple would've sucked. At least we can confident that's not your issue.

When you installed the new radiator, what'd the coolant look like after? nice and clear, no sediment? (if you recall)

 

Stating the obvious, but losing any coolant? Any hoses bulging when the truck is up to temperature?

I'd stick with the stock fan. Plus just throwing in an electric fan doesn't fix the main issue on why you were overheating in the first place.

 

I don’t remember right now, but since I am a procrastinator, I still have the fluid in a clearish container at home. Seems like I do remember the color being a little off, though.