Hi! This is my 1st post! My 1999 4Runner has 388,000 miles! Beautiful vehicle I inherited from my brother in law when he passed from cancer. Gonna take it to a million miles, which was his dream.

Has new radiator, water pump, timing belt, and thermostat and complete flush. Mechanic's cannot find why the temp gauge still continues to go to hot, even though no steam or other signs of overheating. Also combustion test shows no head gasket issues. Gauge goes down when heater is turned on.

At times it drives perfectly for 50 miles or so, over hills and curves. Next time it shows hot. I'm sooooo frustrated. Any suggestions would be greatly appreciated. My 4Runner is my baby. 1999 Limited, 2 wheel drive, Fla Georgia truck.....no rust.

Could be a lot of different things. Bad fan clutch, bad radiator cap, air pockets in the cooling system, bad mechanics, blocked condenser, etc.

Can you isolate when it gets hot? Does it happen in stop and go traffic or cruising highway speeds? Only with the ac on?

Did the mechanic use a toyota oem thermostat also an Aisin WP or oem. The jiggle valve on the thermostat should be at 6 o'clock most mechanics not fimiliar with 3rd gens put that at 12. If the system was burped properly then double check that the hoses are not collapsing. Even though you have a new radiator the symptoms point to restriction in the cooling system or exhaust system. Also the radiator cap. If overheating just at idle then it could also be the fan clutch.

Google 'burping the coolant system'. Chances are you've got air trapped and it needs more coolant to top it off. All else fails you replace the Engine Temperature Sender - the little one prong sensor on the water bypass way in the back of the engine.

When you remove the radiator cap is coolant touching the bottom of the cap?

With those miles the fan clutch needs replaced.


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What motor?
When you say hot what does the temp gauge indicate?