We've had our 2006 MMH since June and have had various noises such as the rear end squeak, rock getting caught between the heat sheild and rotors on the brakes, etc. All were fixed to our satisfaction, but now we have developed a new noise.

The new noise is a high pitched squealing (whining) type sound from the rear of the vehicle that occurs only when the vehicle travels in excess of 20MPH, and the vehicle must be warm, driven at least 30mins. Very similiar to a 70's or 80's car that you could hear the alternator sometimes through the radio (going way back for that comparison). Really annoying to say the least as it gets louder and higher pitched the faster you go. Under 20MPH it stops.

Have brought this to the dealer several times, tech's rode with us and heard the noise, but have no idea what it is. At first they thought it may be the brakes, nope. Next time it happened they thought it may be an air leak somewhere. Unfortunately every time we drop it off they can never recreate the problem and it goes unfixed.

So since I had good luck here before with the rear end noise issue (thanks for the link to the TSB, the dealer was clueless) I figured I'd try again and see if anyone has had a similiar issue, or a better guess than the Mercury Technicians.

Thanks,

John

Hi John

There has been many, including myself with the parking brake making noise and an adjustment solved the problem. This is a drum assembly not part of the disc brakes.

The information you posted is great, but not enough to pinpoint the cause. Could you do two test that may eliminate the possibility of many things. First of all, anytime repairs are needed as with the shock problem, other issues could have been caused as a result.

First, do a neutral coast down speed test by exceeding the speed where the noise starts to determine if the noise is still present while coasting in neutral. This will eliminate the engine and torque issues.

Second, do a steering test while the noise is present by making sweeping turns in both directions. If the noise goes away or get worst, the wheel bearings, hubs, U-joints (contained in the axles of the 4WD), and tire tread wear are all possible sources.

Here again, you may need to check rear lubricants and the noise could be from a differential gear.

Good luck and keep us posted!

GaryG

John -
Gary's suggested tests would be valuable. It does sound similar to other discussions of parking brake issues. I would search this forum for some previous mention of parking brake "fixes". I vaguely remember a process of a few quick pulls on the brake handle with the button depressed - to see if the noise is affected - while the noise is present. Be safe.

Check the fluid level in the rear diff.

OK, this riddle has finally been solved. Seems that there was a tab broken off the battery air filter door located on the rear drivers side of the vehicle. In turn, the door would not close properly. Thus, when the process of moving air began, so did the high pitched whistling. The current door has been sealed for now and a new one is on order. Just another "who'd a thunk it"........