Q: I have a 2006 Toyota RAV4 with the following problem: When I back out of my driveway each morning and place the transmission in drive, a clunk is heard from the rear of the car. I don’t recall hearing the noise at any other time when driving. I’ve had this looked at twice, and they were either unable to duplicate the problem or thought it might be a normal sound. It has four-wheel drive and around 83,000 miles on the odometer. Any suggestions?

A: Noises are probably the most difficult thing for me to try to help with. Lots of folks complain about clunking noises from the steering column on your vehicle, but noises from the rear are rare. Since the noise only seems to occur in the morning I’m wondering if the combination of cold rear differential fluid and elevated idle speed may be causing a brief jolt in your Active Torque Control coupling within the rear differential. This is a magnetically applied clutch pack that blends engine torque between the front and rear wheels. The clutch plates are immersed in the 90w differential fluid and may be a little cranky during the first engagement of the day. Limited slip rear axles can be similarly affected when making sharp turns.

How about this: If you’re sure of the exact conditions bringing on the clunk, try selecting the 4X4 button one morning prior to backing out of the driveway. This should lock the clutch fully, and likely will change or eliminate the noise, if I’m on track here. Be sure to immediately release the 4×4 function as soon as you’ve moved a few feet forward, as you don’t want to rough up your mechanisms and tires driving more than a few feet on dry pavement this way. Another thing to try is to note your cold engine RPM on the tachometer and try to duplicate this same engine speed (one foot on gas, the other on brake) as you exit your driveway with the drivetrain at normal operating temperature. If the clunk is there any time of day, we’ll want to look for other more likely causes.

It’s prudent with a noise like this to have the vehicle inspected by a qualified technician. Things to check are rear differential mounting bushings, driveshaft universal joints, axle CV joints, suspension bushings and shock absorbers, and exhaust tailpipe hangers.

— Bergholdt teaches automotive technology. Email questions to under-the-hood@earthlink.net.