A 4.3 2000Blazer every time I start it has a thump it only does it about 80 percent of the time.Put new motormounts ,transmission mounts ,new starter and had the timing checked but the thump noise is still there
Are you trying for 100% ?
Seems he’s trying to provide info that might help.
tell us more about the thump:
how long does the thumping last?
when does the thumping start?
Does the thumping happen just during cranking? and then go away when the truck starts?
What does the thumping sound like? Metal? plastic? air wooshing? any help you can give on this?
Any other starting issues?