I'm working my ole d4 about 5 hours per day clearing brush. She starts fine{with either} and runs good , but i'm using 2 qts of oil per day and I have alot of blowby in the oil filler tube.-- ok week rings-- ? is this-- can I pull pistons and replace rings and inserts or do i need to sleeve --or bore cly-- is this a field job or do i need to pull engine and send to cat ,they are so exspenice.If I can just replace rings and inserts that would be cheeper-- if it would work. I did fix my spring the way way you said the brass works - GREAT ---THANKS JIM

Hi Jim,
Glad to hear you got the spring back in operation:)

Pistons/rods and liners are quite commonly pulled and serviced in the field. About the only special tool is a disc the right diameter to pull the liners along with measuring instruments.

It's all about specs:
Rings are readily available.
Pistons can be reused if the ring lands and piston diameter are in spec.
Liners can be honed and reused if not worn or tapered beyond specs.

Usual rebuild is to replace liners/pistons and rings as a set.