Scary Random Engine Clank/Tap

[Jon B]

I will have to double check if I could even get slow motion movements- that’s good info thanks...

Yes, the tensioner pistons are extremely slow to depress when functioning properly. You can use a large pair of channellock pliers to compress them.
The manuals say the piston should not depress more than 10 mm after 5-10 minutes, with 12 lbs of weight applied to the piston.

Your idler arms are the original type for your 73.5 engine, without bushings. You should upgrade those.
The divots are normal contact wear after 45 years.

Here are two early 930 tensioners like yours, still with 901 numbers on the castings, and a later 930 tensioner disassembled.
These are excellent tensioners, in my opinion, and I used to rebuild and re-use them quite often.

There's a lot of information in the factory manuals.





Jon B.
Vista, CA