My 1993 ls400 had an occasional engine miss so i decided to replace the plugs, wires, caps and rotors. after install i started the car and heard some screeching and saw the drive belt tensioner pulley was not turning. Removed it and bearing was frozen so i replaced it. When i tried to start the car it stumbled a bit then the starter sounded like it was spinning an engine with no compression. checked the compression on #6 cal and have about 20 lbs. did it jump timing

 

Or the timing belt broke. If valves were closed in that cylinder you might get just that amount. So what did the other cylinders check at?

 

I just checked one cylinder. i fear something might have fallen into the timing belt channel when I had the covers off to replace the distributor caps.

 

Since you know how to take them off and since the driverside is the easy one, pull it and check the belt. If belt is good continue with the compression check and report back. It is likely something happened up front.

 

i removed the cam pulley covers and the drivers side cam is out of time the passenger side is in time and a small chunk is missing from the timing belt have no idea what caused this

 

what usually causes the belt to fail is not the belt itself but the pulleys that give tension and idle. the bearings go bad and seize causing the belt to overheat and break (or maybe in your case chunk off). when was the belt last replaced?

if you see the timing is off, then that's a bad sign already. it's always a good idea to replace the hydraulic tensioner during a timing belt job to ensure proper tension on the new timing belt.