2004 S60 AWD 2.5T 120K. Running perfectly only couple of times, when parked overnight, start off in the morning, put in reverse seems like locked in the drivetrain, rock to forward, it bangs in to motion, sounds pretty scary, Bang! like unlocked some joints in the drivetrain, then everything went ok. It happened several times either in winter or summer, in garage or open parking places. Most of the times, washed car the night before. I thought the drive shaft were frozen when it happened once in Winter.

Any thoughts? Could be any problem in the drivetrain, excessibe backlash or problem in universal joints? The sound comes from the rear chassis.

Thanks in advance.
John

have you checked your transmission fluid level recently? if not, do it. and if you haven't changed the fluid, do that also. it sound as if you might be a little low. actually, it sounds like you are alot low.

I just had 120k service in Dealer one month ago, I suppose they checked the fluid level, but I will check it tomorrow. Thanks for the reply.

John

BTW, how do I check the transmission oil level? Any dipstick or sight glass and where? I don't see any info in the user's manual. Thanks a lot.
Is there a level/pressure sensor monitoring the level and generates codes if the level is low?

John

An update:

1. I found the transmission dipstick, it is under the Rad hose close to the engine block on the right hand side if you stand in front of the grill facing to the wind shield.

2. As to the bang noise, it was the park brake lock. This happens after wash the car, and sit in Garage over night. Not to use the park brake after wash the car may avoid this from happening. It is ok to engage the park brake after one night.

Interesting...I have a manual, and don't leave it in gear after I wash it because the pads tend to freeze to the rotors. I use the parking brake only after washing and have no problem.