Blue Smoke when hot or high RPM

[ADEN]

My engine was rebuilt 8 months ago,
New valve guides
New valve seals
New rings
Water pump
Oil pump
Head machined

He said pistons groves where a little worn and where i live i couldn't find new pistons so i had to put my old back.

Right after the rebuild engine smoke blue when hot and idling only, oil consumption 1/4 every 700 kilos.

Maybe stupid mechanic was wronge at some point, but why smoke when hot not cold?

Only thing he didn't change is the head bolts.
Can a loose and hot head let oil escape to the combustion chamber causing blue smoke and fuel consumption????

1989 320i m20b20

[Jaxx_]

Does the engine miss at all? does it run well? was valve stem to guide clearance checked? how do the spark plugs look?

[ADEN]

Does the engine miss at all? does it run well? was valve stem to guide clearance checked? how do the spark plugs look?

Yes, engine miss when niddle in the middle, valve stem to guide clearance idk my mechanic did it, spark plug foulded.

[ButtJuice]

Needle? Middle of what, temp gauge?

[jeffnhiscars]

If he didn't hone the cylinders the rings may not bed and seal and head bolts are a one time use so no telling if the head gasket is sealing.

[ADEN]

If he didn't hone the cylinders the rings may not bed and seal and head bolts are a one time use so no telling if the head gasket is sealing.

Thanks but please confirm, loose head can let oil enter the crankcase and burn?