Overheating diagnosis - 2001 access cab 4x4

Commuting home on the highway today I looked down at the temp gauge and it was in the red. I quickly pulled to the shoulder and let off the gas to idle. I could smell antifreeze, but very slightly.

The gauge settled into the normal range and I limped on down the shoulder to the exit. At the gas station I saw the overflow bottle was empty and filled it with the engine running (with water) - it lowered once or twice before settling. The water started boiling in the overflow so I turned off the ignition to let it cool for 15 minutes and restarted it. From there it was fine, but on surface streets at low RPMs. I saw no white smoke form the tailpipe and the oil looked perfect on the dipstick. I also smelled a bit of antifreeze in the engine bay. No sign of leakage around the radiator cap.

I didn't see any obvious leaks but I am tempted to just replace the radiator, hoses, and thermostat because, with 240,000 miles, those are ready to be replaced anyway (it has a 6 month-old OEM timing belt kit with water pump), but the fact that it drove OK at low RPMs but was hot on the highway seemed kind of 'head-gasket-ish' to me.

Any thoughts? Any place these are known to leak coolant? I would love to find a leak and not have to get a leak-down test.

Thanks!

 

Coolant hose diagram should be in the FSM in the mega thread. How’s the transmission fluid look?

 

Don't forget to add new radiator cap to the mix.

 

Also check your fan clutch

 

This could be the whole issue if the coolant was boiling in the overflow tank before the temp got too high.

 

It is the cap as Shifty and NickB_01TRD say - spring has gone weak and does not hold correct pressure letting it out too soon causing boiling.

Replace Only with OEM and preferably one bought directly from a dealer so no one can scam you online with a fake.

 

Exactly.

Too many people fail to understand how important that stupid little cap is.

 

I've seen it 3 times personally. My camry has done it twice, I shut the car off and I can hear it boiling in the reservoir, no overheating though. My side by side did it as well which overfilled the overflow and it poured out of the top.

 

Thanks, folks. I am sure hoping it is jus the cap!