Yesterday was a day of repairs… Driving home from work on Friday I found the 4Runner to be overheating! It was odd as the temperature gauge was fluctuating pretty severely, going hot fairly fast but cooling itself back down. I never really had a problem with high temps before with this truck so this was new.
On the way home I took it through a car wash hoping to see the temps drop, but it only heated up more. I had turned the truck off to let it cool down while I vacuumed it, which helped, but it only got hot again.
I found the blasting the heater trick didn’t quite work well and didn’t make much of a difference. Nevertheless got it home. I hooked up my scanner and no new codes (Only codes I have are from a “very small” EVAP leak coming from my oil catch can). But I was able to view live data and found my coolant temps in the 230-240’s… ouch. Quickly turned it off and began checking for the obvious. Coolant was still full, thankfully, serpentine belt appeared to be in okay condition, and only one very small apparent coolant leak coming from the back hose of the overflow tank. But no fresh coolant, it was just dried pink.
Next morning I went to Toyota and picked up a new thermostat/housing and radiator cap. Unfortunately they didn’t have the little piece of hose. The hose was actually in fine shape, just looked like where it met with the radiator underneath the cap wasn’t fitting the best. I resolved that with hose clamps for now.
I didn’t take much pictures but replacing the thermostat was actually the easiest thing I’ve done to this vehicle. Remove the clamp from the lower radiator hose, remove the hose, take off the 3 10mm bolts holding the thermostat on, wipe everything down, repeat for the installation. Thermostat didn’t appear in terrible shape but I’ll test it today with the boiling water trick, same with the radiator cap.
Got it all together and with the cap off was ready to start burping the system to see if any large bubbles could’ve been the culprit. Started the truck and heard the worst belt squeal I’ve heard in my life! After a quick inspection I found the belt was actually in bad shape and I didn’t check it well enough at first. Got a new belt from Autozone, threw it on, and it worked.
Nevertheless I bled the system again with one of those cool funnel systems from Autozone which made the whole task easy (see pic below), made sure it was filled up with fresh Toyota Pink 50/50 and took it for a test drive to the grocery store. All went well and live temps stayed around 180, much better than the 230-240 earlier. Plus my heater felt like it was working way earlier and much better.
Could it have just been a bad belt… maybe. Radiator cap… maybe. Thermostat… maybe. Regardless truck is in the 160,000 mile range and replacing those parts is just insurance at this point. I can’t complain though, this truck’s been good to me and the only thing I’ve ever replaced that was busted was an alternator.
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