I'm thinking about purchasing a 2010 Mercury Mariner, but I hear a weird noise after taking off from a stop. The sound is like a whine jet sound. The noise is loud until 40 or 50 MPH. I can also hear the sound whenever I rev the engine. Any idea what this sound could be? Engine is 2.5 4 cylinder.

 

Could be a problem in the transmission/ transaxle.A power steering pump can whine like that and Ford's a famous for power steering pump noise.Verify the pump's fluid level is ok.You can also remove the serpentine belt and briefly run the engine to troubleshoot the P.S. pump or anything else driven by the belt. I hope the price isn't very high on that Mariner.

 

I better get it checked out. They are asking 9,000 for it. 131,000 miles. They will give 3 months 3 k warranty on the engine and transmission. Runs great and no dash lights are on but I hate the sound. Thanks for replying back.