Newly rebuilt motor, new thermostat fan clutch seems new, and fresh toyota coolant. Wants to overheat when driving in town after 10 or 15 minutes. Fine on long drives. Everything seems to be running fine. any ideas?

 

Check your fluid level. Could be defective fan clutch or clogged radiator.

 

fluids fine, how do i check for a clog?

 

Where to start? factory fan clutch? aftermarkes clutches are garbage. radiator could be clogged. radiator and ac condenser could be full of dirt. clean with compressed air and water hose. fan clutch#16210-65020.
factory t-stat 90916-03079. aftermarket t-stats don't work. also make sure the coolant is properly bled.

 

i think the radiator problems are unlikely.

my guess is thermostat. Its fairly easy to pull it out and put it back together without it in. IF it does fine with out it, toss it and get a new one.

if your still haveing problems after you pull the thermostat, move on to other stuff mentioned...

 

You said newly rebuilt. If the heads were removed and reinstalled, the head gaskits could have been installed backwards. It happened to me. Only way to tell that I know of is to pull the heads.

 

nevermind my buddies an idiot. he changed his coolant from green to toyota red and didn't totally get it drained. So I guess green and red clump up and clog the hell out of everything.

 

Check for air bubble in system. Remove heater hose behind eng. next to firewall... fill w/coolant...reconnect.... set rad. cap at half turn... run eng. for 10 min. Cool down and refill any missing coolant

 

Dont worry about mixing coolant types.. no prob.

 

Disagree and have the receipt for a heater core to prove it. Don't mix types - it's not worth it.