Owners/service Manual problems of the 2005 Nissan Pathfinder

All of my experience with my transmission failure took place on the road while in heavy traffic which was unsafe and scary July 2014 - present. First, the truck developed a “bucking” movement whenever it was driven. The bucking movement is similar to a car that is trying to shift gears like a manual car, but the transition between gears was not smooth. Gradually and unexpectedly, while driving, the car started making reving noises like a race car, while the speed is only 20mph. The speed dropped and would not accelearte regardless of how hard you are pressing on the gas. To decrease the reving noise you cannot drive above 40mph. As always I rely on the dealership to service my car, and at first the diagnostic test did not show the coolant leaking into the transmission. With more and more test by the Nissan mechanic, there was still no indication by the diagnostic test that shows the increase defect of the transmission. 3 weeks later, after handing over the car for a complete day, the dealership strip the car and ran further diagnostic test which indicated that the transmission failure due to leak from the engine coolant liquid mixing with the transmission fluid leading to an automatic transmission damage. The recommendation by the dealership is to replace the transmission, which would cost $5,000. Remaining payment balance for the car is $1700. Total mileage on the car is 100,200.