Transmission problems are common in this model, often as a result of a failed front pump. The pump loses its ability to create hydraulic pressure, which an automatic transmission needs to function. A sign of front pump failure can be a whine type noise.Google+
Car Problem Reports
Mercury Grand Marquis Transmission Failure Common Due to Front Pump Failure
Mercury Grand Marquis Problem
Average Mileage: 71,375 mi (40,000 mi - 135,500 mi)
Visitor, 2006 Mercury Grand Marquis, 49,000 mi
MINE WILL SLIP, WHEN GOING AT AN EVEN SLOWER SPEED, TRYING TO GO UP A GEAR, IT HUNTS FOR THE GEAR FOR AWHILE AND THE ENGINE REVS, BUT CANNOT FIND THE GEAR FOR AWHILE. THEN IT FINDS THE GEAR AND IT IS FINE.
Visitor, 2007 Mercury Grand Marquis, 61,000 mi
Whining noise in low gear, changing frequency as it slips into 2nd gear. Some of the same noise as it accelerates in 2nd gear. Not noticable after gets in 3rd and 4th. Ford dealer says it's common and not a problem as long as the car isn't loosing power. (DUH).
Visitor, 2006 Mercury Grand Marquis, 135,500 mi
Revs up before it takes off after stopping. Shifts in and out of gears as I drive.
Visitor, 2005 Mercury Grand Marquis, 40,000 mi
just after buying car few years ago car whined in and out of gear then catch be ok. we got it checked but brought it back several times right after warenty exspired they told us we need a rebuilt transmishion. so upseting 3,000 later..
Visitor, 2006 Mercury Grand Marquis
2000 mercury marquis, 155,000 miles. Transmission Whine, fluid clean and up to level. Shifts fine has a whine all gears.