What are the things that can cause an engine to overheat?
Here's a partial list. What am I missing? I'm stumped on my Toyota Tacoma.
- Make sure fan is rotating
- Check/replace the fan belt
- Check any fan fluid drive joint
Make sure radiator is clean and clear of debris
Replace radiator (as it might be internally clogged or corroded)
Replace radiator cap (and get one with the correct pressure settings for the vehicle)
Tube to recovery tank with a slight vacuum leak thus leaving radiator not full as engine cools down
Visually look for coolant leaks
Pressure and/or vacuum test cooling system
Flush system with a garden hose until only clear water emerges
Check the coolant type for the vehicle
Replace the coolant
Test the coolant to water ratio (at 50% in my case for glycol)
Replace thermostat. Consider that you might have been given the wrong thermostat. Also they are available in different opening temperatures. For my vehicle I saw 180 degrees as standard, and 170 degrees as optional.
Test thermostat it in a pot of water on the stove with a thermometer and caliper to meet factory service manual specs, i.e. what temp it's suppose to start to open at, and how much it's suppose to open. NOTE: I live at 6000 feet elevation, so water here boils at about 200 degrees, which means the thermostat never reaches fully open in the pan on the stove, but it's close.
Make sure the thermostat is in the right way (i.e. flow direction is correct, and wiggle hole is up)
Make sure the thermostat is the right thermostat. Try to verify that both diameter, length and temperature set-point are correct. Somehow I got the wrong part. It was too long. Even though it opened correctly in a pot of hot water to manufacture's specs, it wouldn't open in the truck as the end that closed off the bypass would impede the end that let the main amount of water flow. But thinking that since it was both new and had been tested twice, this then caused me major headaches looking in vein for overheating causes coming from other things.
THE WATER PUMP
Wiggle the shaft to see if it's bearing is bad
(How can one tell if it might have cavitation creating bubbles?)
POSSIBLE HEAD LEAK (exhaust leaking to coolant creating bubbles)
Check block to head joint, (in my case head was resurfaced by a quality machine shop)
Check compression (to be to spec in all cylinders)
Smell exhaust for a sweet smell
Chemically test coolant for exhaust gas in it (with an indicator-solution test kit which turns from blue to pink if exhaust is leaking into coolant)
Replace head gasket
Replace head bolts (in my case of the stretching type)
Carefully torque and spring load the head bolts
(this includes checking a whole long list of things like carefully visually inspect block and head flatness and smoothness, check bolt and hole length, and that washer with correct side up, and oil is applied to each bolt and washer as installed, and that hole is blown out first, and factory packing sealant is applied as directed, and bolts are smoothly tightened in the factory specified order, and with a dial angle gauge)