Re-ring

[npca-willie]

My patrol is burning a lot of oil,I just had the head rebuilt with new valve seals.I have heard the patrols can be re-ringed without removing the engine.Has anyone ever done this?The cylinders look to be in good condition,there are no scrapes or grooves.You can still see the cross hatch. Thank you,Willie

[npca-viking]

I have not done a ring job on a P40 in the vehicle. I have bored, edged and honed one out of the vehicle to 30 thousand oversize (new pistons etc) and can imagine no difference given the amount of room available under the hood though that would depend on the type of line boring unit used in the first part of the process. It is that part which is critical and most often neglected. Honing can not correct an eliptical wearing of the cylinders which is common fate in all vertical piston engines given the lateral thrust of the pistons against the cylinder walls being more side to side than end to end. You say you can still see the cross hatching? Is that consistent completely around the bore or are there marked bare metal surfaces without that hatching on opposite sides from each other? If so, you may have to rebore to correct that out- of-circle profile of the cylinder - then the rings can expand against all surfaces of the cylinder evenly and seal properly.   My manual tells me that the alignment of the 3 piston-ring end gaps relative to each other is critical to minimize blow-by in the P40. Did you have a ring job fairly recently in which the person doing it may not have taken that into account? I can look that up again and send it to you if that might be the problem. In any event, I hope you find the problem. Please feel free to "E" mail me.