Exmark 22.5hp blowing white

[Rocky J]

over filled with oil will also cause this, maybe leaking carb N+S

I have had both of these issues you mention cause clouds of white smoke. One was a dip stick from another engine tricked the user to overfill , if it fits it ships . The other was carb not shutting off the fuel and draining into the engine oil, common on models with gas tank higher then engine .

 

[RevB]

Severe amount of white smoke problem is this winter I rebuilt it split sump everything looked great new head gaskets and the valves were lapped to remove little pitting today I put the engine back on and it is still smoking like last year I have checked the read valve seems to be working as it should I am at a loss I unscrewed the oil dip stick and cranked it over and oil shot out the tube so I pulled the flywheel and the breather I do t see a clog anywhere I am so confused on this any info would be great

Lapping does not remove pits. All you did was polish the pits.
What were the condition of the valve guides. Are there oil seals on the guides.

 

[RevB]

Leak down test 6 to 7 percent on both cylinders and that me trying to hold and plug in at 100 psi

I wanted to update everyone on this problem I took the engine out last night and tore it down today this mower is a 2017 model with 218 hours once I pulled the pistons cylinders 2 I think the lower one anyways the compression ring end gaps were maybe an 1/8th of an inch apart so ordered complete rebuild for 200 bucks did my honing and lapping and will let everyone know how it turns out had to be a factor issue as this is it's first complete tear down

A complete "rebuild" as in next oversize piston? Cylinder machined to fit? At 218 hours I'd seriously think about rebuilding something that only lasted that long.

 

[RevB]

Have more questions than answers. Before ordering any parts please help us.
1. Please supply us with all engine numbers.
2. Did you measure the cylinders with a telescoping and vernier? Two measurements at top, middle and bottom, 90 degrees apart. This will tell us if you need to go with oversized rings and piston.
3. Measure ring end gap. Most rings will have a gap of .025”-.045” depending on brand and engine size. Saying the end gap is near .25” tells me you have a problem that won’t be fixed cheaply.

Finally.

 

[Gord Baker]

Don't overthink this. Run it for 30 minutes and note any changes. Clear Crankcase vent tube. Oil at correct level?
Ring Dia appears correct. 0.004" per inch of bore is nominal. Did you stagger the ring ends 120°? They must NOT be aligned. Re torque head bolts when Cold. Not worth expensive rebuilding IMHO

 

[S.A.E.]

A complete "rebuild" as in next oversize piston? Cylinder machined to fit? At 218 hours I'd seriously think about rebuilding something that only lasted that long.

be sure to flush ALL grinding compounds and trash from all pathways.

 

[kbowley]

Respectfully, none of the above are related to your issue. Your cylinder, rings, and valves are great, as your leakdown test confirms. The issue is: crankcase breather, oil pressure, or valve guide(s). Now, could you PLEASE provide us with your engine information, please! Hell, we don't even know the manufacturer of the engine, so provide it, or I am out.

 

[lumpymags]

To finish off this thread a lot of great info you all gave me thank you. I think I put a period there. It was the rings and I figured just do the rebuild machine shop was nuts on head surfacing so I did do the 80 grit 150 to 600 grit paper on block and heads first start no smoke and purrs like a kitten

 

[Gord Baker]

To finish off this thread a lot of great info you all gave me thank you. I think I put a period there. It was the rings and I figured just do the rebuild machine shop was nuts on head surfacing so I did do the 80 grit 150 to 600 grit paper on block and heads first start no smoke and purrs like a kitten

Well done sir.

 

[kbowley]

I find that very strange, as defective rings or a warped head would show up in the leak-down test. However, the oil rings could have been installed upside down and allowed oil to pass by. Also, you never posted your engine manufacturer or model number. Weird thread.

To finish off this thread a lot of great info you all gave me thank you. I think I put a period there. It was the rings and I figured just do the rebuild machine shop was nuts on head surfacing so I did do the 80 grit 150 to 600 grit paper on block and heads first start no smoke and purrs like a kitten