Fix car for added trade in value? (2001 Infiniti QX4)?

I own a 2001 Infiniti QX4 SUV that I will be trading in very soon. The car has a problem with the water pump, or something to that affect. I've had two estimates that place the job at somewhere between 900-1200 because the transmission must be removed to fix the water pump/random water thing, so the labor constitutes the brunt of the cost. The car cannot be driven because it will overheat without this part. Should I fix this part to provide a better price point for trade in? Or should I byp the fix and just tow the car for trade in? How much value would be added by fixing this part as opposed to leaving the car as is?