1996 4Runner with 3.4, auto, 4wd.

I've been monitoring my coolant temps lately (using a bluetooth OBD2 reader/app) and I cant seem to ever run less than 212 degrees, even on the highway in 50 degree weather.

Radiator is OEM, less than 12 months old. Hoses, radiator cap, coolant temp sensor, and thermostat all replaced at that time. Coolant burped with a proper radiator funnel. Just replaced the radiator cap again cause it was quick and cheap. Just replaced the fan clutch because its original and old.

The jiggle valve on the t-stat is at the 6 o'clock position.

Heater core is completely bypassed during the summer using a ball valve instead of the typical plastic control valve.

Really strange to me that that it always seems to level out at 212 degrees specifically.

What variables are left other than a failing water pump?

Possiblities:

You need to do a leak down test to see if your system is building up pressure.

because if its not building pressure you have a leak somewhere.

Extremely rare:

bad thermostat, water pump (would only be a seep or a leak you would see)


You changed all the normal parts already.

I would try a cooler thermostat. One that opens below 180 degrees.

Your clutch fan was changed so that should eliminate that.
Being your in the the super hot zone. See if you can find one that opens at 160 degrees that is if your system builds up to normal psi on your leak down test. :-)

Maybe try a mechanical gauge?
Is there maybe more than 1 coolant temp sender? 1 for the ECU and 1 for the gauge?

There are two, the one on the front top of the engine that sends data to the ECU and the other on the back of the block that sends the signal to the gauge. It would be the Engine Coolant Temperature Sensor in the front to try replacing if nothing else works. Many parts stores will also let you rent coolant system pressure testing kits to look for leaks.

When you replaced your parts, how did the system look? Orange and scaly everywhere or pretty clean?

Probably have a large amount of air pockets in the cooling system. This system is one of the hardest one I have ever had to expunge air in.

Thermostat OEM? Age of the water pump?

Why do you bypass the heater core with a ball valve?

The stock heater control valve has failed on me a few times. Ball valve was simple and cheap. I open it up in October and burp the cooling system.

Sorry if I missed this in your original post, but have you borrowed another gauge like a friend's Ultra Gauge or one from a parts store to get a 'second opinion' on the coolant temp?

What were the brands of each of the components you replaced? I have seen bad thermostats, radiator caps, etc. if not OEM.

-Charlie

I’m gonna phone a friend and see if @Bad Luck has any input on this one…

I'm with you and find the temp cited consistently as a suspect reading. Prove it with another device.

I feel like I've finally been chosen first for dodgeball lol

1) How are you monitoring temps?
2) When you let it sit overnight without running how close is your coolant temp to ambient temp?
3) When you bled the cooling system did you open the ball valve for your heater core? Did you elevate the front of the vehicle? Did you allow the engine to get to operating temp for a few minutes before calling it good?
4) I too want to know what brand of components you put on.

My 97 used to run in the low 200's on hot days. My radiator, coolant, thermostat, water pump, radiator cap etc was all replaced (OEM parts) but it still would run "hot". I also bled the air out multiple times to no avail.

Once I replaced the fan clutch with an new OEM part, I never see temps in the 200's anymore. I know the OP said he replaced it but maybe he didn't use an OEM fan clutch. Hopefully he'll chime in here soon so we can get him on the right track.

As mentioned before, I would verify first that his reading are accurate to begin with.

The fan clutch is such an essential component to keeping engine temps nice and cool. I tell everyone I can to replace theirs if they’re ever experiencing higher than normal operating temperatures. It only took me 8.5 years to figure it out, lol.

To the OP, if you didn’t use an OEM fan clutch I would highly advise doing so. The OEM one is an Aisin product and can be had from Amazon or RockAuto for under $100. Should be p/n FCT-013.

You've addressed all the components that could cause your high temps. This only leaves a potential issue with the water pump but I kind of doubt that's the issue.

I'm wondering if this has something to do with how you bypassed the heater core. I would open the ball valve, re-burp the system, and then drive around with the ball valve open and see how that affects your coolant temp. You are running VERY high. A normal coolant temp for these rigs is around 188-194 unless you're driving in very hot temps and going over steep grades which will cause the temp to rise to the level your currently running at.