Pioneer 500 rebuilt again, still burning oil

[Pax]

My ‘18 pioneer 500 has been a headache. Issue started 2 years ago with dust ingestion from air filter not being on all the way, 600 miles at the time. Had top end rebuilt, blew again within 75 miles. I had a different shop (both non-dealers) replace jug (own) and piston (Nembutal). Went about 75 miles again and crank went out. Had crank replaced, rehoned and rings. Went about 100 miles, still burning oil. Honed and rings again. Mechanic had me put 300 miles on this time, burned oil entire time, getting worse with more miles- oil not on dipstick after 1/2 tank of gas. Had it bored and new top end (this time own). Started burning oil again around 100 miles. Any ideas? He warrantied his work which is great- down side he keeps it 4-5 months every time I drop it off. It’s literally been at my house for about 5 months since fall 2020…..Any thoughts on what the issue could be?
Thanks!

 

[906UP]

Is the crankcase vent plugged?

 

[Pax]

Is the crankcase vent plugged?

Would that make it burn oil? Another piece of info is that crosshatch in jug has been gone after 100 miles each time.

 

[Jerryg]

Cracked cylinder head, oil filled muffler.

 

[Mopower58]

Would that make it burn oil? Another piece of info is that crosshatch in jug has been gone after 100 miles each time.

If the crosshatch is gone each time, sounds like the air intake hose is leaking between the air filter and cylinder allowing dust to enter. Dust/dirt will act just like sandpaper on the cylinder wall.

 

[906UP]

Would that make it burn oil?....

Yes, the crankcase builds pressure as the piston moves down, vacuum as the piston moves up, if the vent is blocked it will force oil past the rings.
This is the hose, about 3/4" dia that goes from the left rear of the engine up to the air cleaner box

 

[bigshoe]

I've screwed up before and done this myself, but he's prob putting rings on wrong they usually run about 100 miles before they give up the ghost. Also honda oe parts or nothin. I make customers sign that I'm not warranty anywork that has ebay or Amazon parts on it

 

[Pax]

Yes, the crankcase builds pressure as the piston moves down, vacuum as the piston moves up, if the vent is blocked it will force oil past the rings.
This is the hose, about 3/4" dia that goes from the left rear of the engine up to the air cleaner box

Thanks a lot, I will check it out

If the crosshatch is gone each time, sounds like the air intake hose is leaking between the air filter and cylinder allowing dust to enter. Dust/dirt will act just like sandpaper on the cylinder wall.

The only reason I don’t think that makes sense in this case is since the last rebuild it has only been driven in spring conditions on pavement and damp Forrest service roads- still a month away from dust season where I live.

 

[Pax]

I've screwed up before and done this myself, but he's prob putting rings on wrong they usually run about 100 miles before they give up the ghost. Also honda oe parts or nothin. I make customers sign that I'm not warranty anywork that has ebay or Amazon parts on it

Thanks, this time around it was all OEM, even showed me the packaging. Could be that he’s doing rings wrong but 4 times?

 

[Pax]

If anyone is looking for a deal…..walker evens, winch, heater, soft cab, snorkels (only for dust), and Camso tracks with about 75 total miles…..located in North Idaho…..

 

[Ohio4x4]

Thanks, this time around it was all OEM, even showed me the packaging. Could be that he’s doing rings wrong but 4 times?

Whats been done with the head during these rebuilds. Ive had ranchers and foremans wear the valve stems and guides causing bad oil consumption.

 

[Pax]

Whats been done with the head during these rebuilds. Ive had ranchers and foremans wear the valve stems and guides causing bad oil consumption.

He’s checked valves and replaced valve seals.