K241 Burning Oil Problem

[dvogtvpe]

I guess when you hit quote it only quotes the poster and don't include the quotes that he quoted. hopefully you all get the picture

[OffTime]

Originally Posted by litlmikeyl

Results - The amount of smoke has gone down a bit and some of the blue is gone. It's more of a whitish color but you can smell oil if you walk past the muffler outlet. Also I don't get the oil spatter out if the exhaust like before. Either way, the motor gets to come out. Bummed I am.

I have been watching this thread to see all the input. I have to agree with Don and Jonathan. Improper skirt clearances, not enough ring gap or dirt. Or a combination of that with maybe another problem or two.

A note on the blue smoke and oil smell. Once a muffler get saturated with oil, it can take hours to burn all the oil out and clean up smoke and smell. So when you rebuild your motor again, it may still smell like and look like it's burning oil for some time. Don't use that as an immediate indicator as to oil consumption.

[litlmikeyl]

I was able to pull the motor and get the piston/rod out of it late last night and its way worse than I expected. Here's the brekadown:

- Breather assembly: The drain was not only plugged, but blocked off entirely. The gasket came up at least 1/8 - 3/16" past where the drain hole is which kept at least that much oil sitting in the cavity. I had no reed valve so on positive crankcase pressure it would exhale through the breather as usual but it would also inhale through the same path during a vacuum situation. I'm pretty certain the motor injested dirt and debris through this to some degree though how much is unknown. It only makes sense that it would pull in debris somehow given the breathers' state of function.

- Cyl Head.: The photo below of the oil sitting on top of the piston is after 3 minutes of running with a new head gasket on the milled head. It seems worse than when is origianl problem was identified.

- Rings: All the rings look fine with no nicks, dings or scrathes thoughout. They are currently still on the piston so I have not measured the gaps to see how they faired and none of the gaps lined up with each other upon removal of the piston from the block. The only visual issue (if it's even an issue at all) is the spacer for the bottom rings has some scuffing where the gap for the upper oil ring was.

- Piston: The sides/skirts are scuffed up pretty good on both sides to the point its close to what the original piston had when we pulled it out for the rebuild. Also, as seen in the photo the top edge has been worn down which is on the S/G side of the motor. Curious how this happened.

- Rod/Crank: The groove shown is solely visual as nothing can be felt by hand or with anything else but it does look really bad. The crank journal on the other is worn out-of-round to the point you can feel it with the meat of your finger. I meaured it out to be in the range of 1.500" down to 1.483" and the crank was at 1.500" after the rebuild was complete. My old crank was too far gone to be ground down to work as intended.

- Block: All of the cross-hatching is gone with no other damage found on the cylinder walls. No grooves, dings... anything. There is an 1/8" layer of sludge in the oil pan that does have a good amount of "colors" mixed in with nothing large to be found that would raise concern. The oil that came out the second time looked nearly ideantical color-wise as the first motor break-in. Another issue found was the end pushrod for the points that rides on the cam is mushroomed a fair amount and there is a light groove on the cam where this rod rides.

After all of the initial findings, I'm left with a few questions on what could've happened and what the effects would've been. Those are:

I changed oil after 5 hours and then at 28.6 (current reading) and am wondering if that could have contributed to this failure. Did I change the oil at the correct intervals?

I know I didn't check the oil level as often as I should have and am wondering if it used oil from the get-go and I ran it low would've that mistake contributed to this failure?

If the motor would've run hot or in a lean condition, would've that contributed to the failure as well?

[dvogtvpe]

it wasn't oil change intervals. breather will cause allot of problems. did you check what the ring gap is at now? its probably within a good range now since the bore is worn. when ring gap is tight it creates allot of pressure on the walls which would cause allot of wear. I'd suspect ring gap was your problem or the block wasn't clean enough when you put it together

[litlmikeyl]

Pulled the rings off to check the current end gap and now I'm not only intrigued but also really confused. The 3rd & 4th rings were so loose they had no spring outward to hold themselves in the bore and fell out. All four were in the .010/.020" range when the motor was reassembled; I am absolutely certain of that.

Top ring = .038"
2nd ring = .081"
3rd ring = .177"
4th ring = .168"

How the poor thing still ran given the above measurements is also a bit baffling as well.

[dvogtvpe]

you'll probably want to check the bore to see if you can clean it up. .030 is your only option since its .020 already

[J-Mech]

Well.... with no reed valve, yeah, it could have sucked dirt. But since you used it in the winter pushing snow, I doubt it sucked much dirt. What happened to the reed? Why was it missing? What was plugging the drain hole? I don't understand how the gasket could have covered any of the drain holes.

I think that it probably had too tight of piston skirt clearance. Too tight of piston coupled with an obvious overheat (warped the head) and you get shaving in the cylinder. That metal, into the oil, which then got the crank/rod. That along with possible dirt from the vent, and I'm going to say not clean enough block on assembly= failure. Are you sure you put the right ring in the correct groove? Can't really tell from the pics.