5.7 won't start when hot

Anytime the weather is warm enough to use the AC the engine overheats and won't start after shut off. Once even went into limp mode and had to tow it home. Always starts after cold.

 

If the engine goes into limp mode, you should be able to pull codes from the ECU to give you some hints.

 

Of course that was the first thing I tried. It is throwing no codes.

 

Well, your best bet is to figure out why the truck is overheating. There are a bunch of things that you should check, and I would recommend checking all of them.

1. Get an exhaust gas in the coolant detector kit to be sure your head gaskets are OK.
2. Is the engine driven cooling fan spinning?
3. Is the radiator super dirty and plugged up?
4. Is the coolant level in the radiator full? (check this with the engine cold)
5. Does the truck overheat with the thermostat pulled out? When you pull out the thermostat, you can put a pot of cold water on the stove with the thermostat and a thermometer in it and slowly heat it. There are specifications for when the thermostat should open.
6. Tundras are somewhat known for needing the occasional water pump replaced. I would inspect your water pump thoroughly for leaks and possibly pop the serpentine belt off to check for play in the water pump pulley.

 

Check the Cats.