timing mark moving
 

I have a 1991 Toyota pickup 4x4 with the 3.0 v6
When I tried to adjust the timing the timing mark was moving in a circle with the harmonic balancer any clues as to why this is happening. Also what 02 sensor part number for the dense will fit this truck

timing mark moving
 

Likely the pulleys on the harmonic balancer have separated. They are held together with a rubber layer in the manufacturing process.

Do you mean Denso for the O2 sensor?

Yeah I changed 5he harmonic balancer last night the old one was shot. And yes denso for the 02 sensor trying to figure out the part numbers for both of the 02 sensors