I have a 2002 Mitsubishi Montero Limited. It has 112,000 miles on it and my wife and I love it. It never gave us any problems until this fall. It now makes a sound as if you were driving over the ?rumble? groves to prevent you from driving off the road. It only does this between the speeds of 40 ? 50 mph and only when you are decelerating or have taken your foot off the gas pedal. When you press the gas pedal the noise stops. My mechanic thinks it is a sticking valve in the transmission. I have put in a quart of transmission lubricant, but to no avail. My mechanic feels it is not worth the expense to take the transmission apart to check. It does not appear to be causing a problem at this time. We recently drove it from Arkansas to Wisconsin and back with no problems. What do you think it might be? If you know, is it easily fixable and if not could it cause a problem down the road? Thanks so much.
Around 40-45 mph is the speed at which most torque converters lock and unlock. Perhaps yours in not working smoothly.
Are there any symptoms other than the noise? Can you feel anything? Any warning lights?
If you think the problem is in the transmission I recommend getting an opinion from a transmission specialist.
Has the transmission fluid ever been changed? If not or if it has been over 40,000 miles, I would likely change it. Note: changing fluid will not fix a mechanical problem, but it may help it work a little better. Be sure to have the pan dropped and the filter changed/cleaned. I would not do a flush.
Again, this may not fix anything, but neither will it harm anything and if it is due anyway, I would do it. Often transmission fail after a change under this kind of situation. Of course they would have failed anyway. The transmission fluid change does not cause failures.
No warning lights, you can also feel the vibration when it does this.
I would try a transmission fluid change and see if it helps. There may also be a control valve malfunctioning. Again, an automatic transmission expert may be required. TEST, don’t guess.