1991 won't turn over(2200 motor)

It's in a Camry but maybe someone has had this issue. Friend way over temp'd and took out radiator, water pump, distributor, and head gasket. I replaced everything and it will start and run. But, the cooling system needs flushed. Fire it up to cycle the system and then drain and refill. Once it is warm, it will not turn over. Only a click from the main relay but if it sits and cools down, it will fire right back up. Give me some ideas of where to locate this issue.

@BamaToy1997

 

Update: It is not a ground issue. I even used jumper cables to make sure so it had 2 extra grounds. When I got home it fired right up. At temp, it still won't start with key using ignition switch. It will start by bypassing starter relay with key on so I'm going to finish flushing the system and hope I get some advice before I have to trace down wire for wire.

 

So you warm it up and the engine won't turn over. Is the motor locking up? Try turning it over by hand to see if it's locking up when it warm.

 

Engine is not locked up. I can shut it down after warm up and immediately try a restart with key. No joy. Hit bypass switch with ignition on and it fires right back up. Bypass switch is directly to starter.

 

Is the check engine light on? Do you have a way to pull codes? How did you wire the bypass switch? Your going to have to pull up the electical schmatic for the starting system. Could be anything from a bad connection at the battery or maybe a bad ground. Do you know how to do a voltage drop test?

http://www.aa1car.com/library/voltage_drop_testing.htm

 

No check engine light.
Too old for my reader.
Bypass from battery to starter.
Voltage drop from where? I get 12v to starter when cold and 0v when warmed up.

 

Do the voltage drop test when the problem is occurring. Read the link I provided. Pull up the wiring diagram to understand how the system works.

 

If your getting 0v at the heavy wire from the start (assuming) then trace the wire back. If your not getting 12v at the small wire when the key is turn to the start postion when warm check for power at the starter relay. That's why I keep suggesting you pull up the wiring diagram.

 

Another thought. Could be a possible starter problem. The start warms up then won't work. Easy test, with the engine cold use a heat gun and warm the starter. If it doesnt start after its warm replace the starter.

 

To update again. System is flushed. Everything is back together like hood, heat shields, etc.. Has been pretty much at operating temp all day as I've worked on it and shut it off. It has started every time with no issues except the first time today at temp. I ran it through the gears and started it in neutral then. ??It has set for a few months before I started working on it. Maybe something with the neutral safety switch and by running the gears? I don't know. At a loss. But it's working for now so nothing I can do until this gremlin shows up again. Thanks Ruggybuggy for your input. I appreciate your input and interest very much and will be back to update this thread if the issue comes back for those that might run into this in the future.

 

No problem. I would swap out the starter relay with the AC relay. You never know it just might be a failing relay.