If there is a leak on the valve cover gasket does it cause the car to overheat?

 

no, it causes an oil leak, and could lead to a dirty engine!

 

yeah what he said.

 

thanks

 

As said before, no. You'll just get an oil leak.

You're probably confusing it with the head gasket. Some aftermarket designs don't comform to the coolant chambers, thus causing overheating problems. Some blockguards do this too.