1996 es300 overheating puzzle?

[QualityVehicle]

I had to swap motors in my 1996 es300 (rod bearing), so I had my mechanic put in a good (?) junkyard motor that had 120,000 miles on it. It runs purrrrfect now sitting still. I idled it for two hours with no problem, but if I drive it down the road, it overheats. I am at a loss. Can anyone help me out? Thanks.

[snupytcb]

hate to say it but it may be a head issue.

[Scrapper]

could be head gasket or cracked head.but look in your radiator see if it's circulating if not could water pump....

[KimMG]

Clogged radiator?

[QualityVehicle]

The car didn't overheat with the other engine, so I'm thinking it cant be the rediator. I guess that leaves the heads or the water pump. Since the cap isn't on top of the radiator, it's kinda hard to see how well the water is moving. I guess a compression test would eliminate (or point to) the heads, which should only leave water pump???

[Brian R.]

Welcome to the AF!

Could be your thermostat. If it won't open very far, it would produce the symptoms you describe.

[AutoMaintenanceGuy]

the actual junkyard motor is probably the problem. drain the oil out and see if the oil looks a milky brown. that would tell you it is a head gasket problem.