Rings wore out?

[Xternal]

Yea, rings, piston or an altered rod would normally be the problem.

 

[Chevy1925]

Do a wet compression test (put a squirt of oil down the cylinder, then do a compression test). If it goes up, it's rings related. If nothing changes, do a leak down and listen in the intake or exhaust for air escaping. If you do, you have bad valve/s. If you don't, it's short rod syndrome.

 

[GeorgiaDieselGTO]

If you are seeing blowby out the filler neck it will be ring related valves can cause low compression but not blowby. If I were u I would keep on driving unless its gets bad

 

[workin' diesel]

If you are seeing blowby out the filler neck it will be ring related valves can cause low compression but not blowby. If I were u I would keep on driving unless its gets bad

This is the plan!