so i just replaced my clutch, tranny, and rear main seal a few weeks ago and ever since i put it back together my car overheats if i drive it a lil hard.... not like redlining it but anything over 4 for more than like 3 gears itll start to overheat.... never had a problem with it before i replaced the tranny and ****.... now its not leaking any fluids that i can see and i put a peace of wood under it and the wood is clean when i check it so im almost 100% positive its not leaking anything.... what could cause my car to all of a sudden start overheating????

 

thermostat could have gone bad? water pump could be going there is alot that could cause it

 

could be an air bubble in the coolant... this would cause the coolant not to be pumped thouroughly... flush the coolant. also check to see if the coolant is low. look at the color of the coolant and make sure it is clear. also check to see that your fan is working.. hope this helps

 

when i take the tranny off i take off the upper rad hose to make it a little easier, so im assuming u did too. after u drain some coolant out theres bubbles in the system, did u make an attempt to make sure the system was full? i had a friend get air trapped in the thermostat once, took a week to figure out.