White smoke

[Jaymbro]

Hey all, I recently went thru my G9 and did complete rebuild on the motor. When I took it apart the bore look well enough so I just went back with standard ring set. Everything ran perfect for about a month maybe 6 weeks now. Monday night it started blowing white smoke thru exhaust. I thought maybe at first my valve seals but the smoke is blowing the entire time under load. So I guess it’s my oil ring.
I should say I bypassed governor. I don’t run it full bore longer than I would any other motor I own. It does get to full rpm but then I’ll back off throttle and feather it as I drive.
My question is should I have went oversized when I rebuild? I cannot believe I only got a month or more out of these rings before the oil ring gave out. I’m setting at 155 psi which is what I was as soon as I got done rebuilding the motor.
I purchased new standard ring set, valve seals and crankcase gasket and am planning on doing again but really would rather not do this every month or so.
Anyways was just curious if anyone else ran into this sort of problem

Appreciate the help....
Jaymbro

[CP241]

Can you define “look well enough”? Did you measure the cylinder before you ordered rings? Or at least measure the ring end gap at different locations in the cylinder? Understand you didn’t have the cylinder bored but did you run a hone through the cylinder to deglaze it? Was there any scoring?

It sounds to me like you pulled It apart, replaced the rings with a set of aftermarket rings, and slapped it back together. If that’s the case I’m not the least bit surprised it’s smoking again already...

[Jaymbro]

I did not measure the bore but I did hone the cylinder out. There wasn’t any scoring or anything else that was of concern for me, I’m by no means a professional so I could have missed something that was a problem

I bought OEM rings and parts

[slonomo]

When I rebuild an engine I use a cylinder bore gauge to measure the cylinder's shape. Over time the bore gets worn but only in the area where the piston/rings contact (basically in the middle up to the top). You can take the engine block to a machine shop and they can measure it for you for a small fee.

A decently cared for engine will have a nice shiny bore and it will look "pretty good", but that doesn't tell the whole story. If that cylinder is worn enough the new standard rings you installed won't contact the cylinder walls properly or with enough tension and can allow oil to seep past. The shiny cylinder walls must be "honed" to get the shiny-ness off and have what we call "cross hatching", which is what the new rings need to wear into and also to hold oil for lubrication.

One other thing, the orientation of the rings is super important, always follow the factory service manual when doing this or they won't seal properly.

At this point the engine needs removed and have the bore checked. From there you can determine if you need an overbore. In the meantime post some pics of what you find, piston, rings, cylinder, etc. Good luck!

[Jaymbro]

I appreciate all the help you guys are throwing my way. Sounds like I need to get the bore checked this time. Must be something off in there. I got new rings heading this way so when they get here I’ll tear into it.