Engine Internals — Frequently Asked Questions

The questions Win Auto Parts is asked most often about piston rings and engine rebuild parts.

Piston ring နှင့် အင်ဂျင် ပြင်ဆင်ရေး ပစ္စည်းများနှင့် ပတ်သက်၍ အမေးများသော မေးခွန်းများ။

Can I fit new rings without boring the cylinder?

Only if the bore is still within the manufacturer's wear limits for taper and out-of-round. Measure it with a bore gauge first. New rings in a worn, tapered bore cannot seal, and the engine will burn oil straight after the rebuild. If the bore is within limits it must still be honed so the new rings can bed in.

The engine still burns oil after a rebuild. What went wrong?

The four usual causes are: the bore was not honed and the rings never bedded in; a compression ring was fitted upside down; the ring gaps were left aligned; or the bore was outside its wear limits and should have been rebored. Valve stem seals are also worth checking, since they are often left alone during a bottom-end rebuild.

How do I know which oversize to order?

Measure the finished bore after machining and order to that figure. Do not order rings before the machine shop has finished, because the final size depends on how much damage had to be removed.

Blue smoke — is it always the rings?

No. Blue smoke on start-up or when lifting off usually points to valve stem seals. Blue smoke under acceleration and load, together with blow-by at the oil filler, points to the rings. A wet compression test separates the two: if the reading rises when oil is added to the cylinder, the rings or the bore are at fault.

Why do you always ask for the engine code?

One vehicle model is frequently sold with several different engines, each with a different bore and a different ring set. The engine code identifies exactly which one you have. It is stamped on the block and usually printed on the vehicle identification plate.

Do you supply complete rebuild kits?

Tell our trade desk what the rebuild covers and we will quote the parts required against your engine code. Send the finished bore measurement with the enquiry if the block has already been machined.