The first thing that comes to mind if the "clunk" is only on starting is worn or broken motor mounts. Something is moving and allowing things to hit each other. A clunking that is intermittent while running may be a ball or roller bearinng going bad.
You're a clunk-head...
could be bad mounts on either the tranny or engine?
Sway bar bushings
You have either run something over or your car is due for a service
Just out of curiousity, how is the transmission in this vehicle. Could the transmission be out of sync with the engine? This has happened to me when i had the transmission replaced in a dodge caravan, Good Luck
It could be many things. Go get your car checked.
The rubber isolators in the engine mounts have worn out or the CV joints in the drive shafts are worn out.
The Transmission needs SERVICED A.S.A.P Hope This Helps.
Year, make, model, engine size, etc. does help. Possible engine mount, u-joint differential,trany, etc...
Worn CVC joint. Could be bad struts causing the spring to bind. Depends how severe the clunk is. If it is struts, it sounds like the floorboard is getting hit by a sledge hammer.
check engine mounts
The engine would probably be seized up. The starter would only make one clunk each time you turn the key to start.
U-joints. Get a hammer and a punch. Replace both ends of the drive shaft.
probably u-joints on driveshaft
The term for this is called "dieseling" ... nothing to do with a diesel engine, rather it's a timing issue with your cars engine.
See if you can turn the crankshaft by hand. If you can turn the crankshaft 360 degrees you probably have a starter motor that's failed. If the engine won't turn completely, it's probably a thrown rod.
Have the engine and trans mounts checked.
It could be that the transmission fluid is low, or it could be that mechanical parts have worn down. If so, it may be time for a replacement.
Vrrrrrrroommm If the driver puts his foot down. Brrrr-clunk-rrrrr-clunk-rrrrrrrrr With added gear changes.
Or suspension component bushings.
Usually it sounds like a clunk. Put the car in drive, step on the brake pedal and hold it down while you slowly accelerate on the gas pedal. If the engine lifts to one side, your mount is broken.
I had the same problem. The dealer replaced the engine mounts at $550.
if the car is rear wheel drive, sounds like a u-joint. If it is front wheel drive, sounds like a cv joint. It could also be your engine mounts wearing out. If the rubber insulation has worn out then the engine will shift slightly against the mount and make a clunking noise. This happened on my 96 Nissan Quest minivan.
It could posibly be a bad transmission mount or a universal joint on the drive shaft or even maybe loose torque converter bolts
A centipede with a wooden leg