New Stens rings = oil burning.

[Fordiesel69 219]

Got a nice 312-8 with a magnum m12 and it had 1161 hrs on it.  Was an oil burner whenever the gov had to open up, or whenever you accelerated.  It would never smoke once it leveled off.  Tore it down and found the rings to be razor sharp, the piston slightly carbon damaged on the top quench area, and the rings were absolutely shot.  So I cleaned it up and slapped a set of stens rings on it.  The smoke is 80% reduced, but it still smoked a tad when you throttle it, or hit heavy grass and the gov has to open up.

 

I have 1.5 hrs on the new rings, will it take much longer?  Reason being it the rings I got on the cheap ebay kits, and some of the NOS rings I have obtained on ebay work 100% right off the bat.  Never a need for a break in before they will stop smoking.

 

I honed with a 3 blade rigid hone, not a bottle brush / dingle ball hone.

[Pickle 42]

What was the piston to cylinder running clearance? What were the ring end gap measurements? What is the valve guide clearance measurements? The engine should not smoke after proper ring installation if the above clearances are correct.

[Fordiesel69 219]

Valve guides were tight, very tight actually which was quite surprising.  The cylinder to piston clearance was .001 away from max, so it will definatly need bored once it hits 2000 hrs. 

 

Ring gaps were in the middle of the spec in my k series manual.  I don;t have a magnum manual, but they are the same anyways.

 

Top and second were .018 gap, and oil was .014 gaps. 

 

I have a 5 arce lot to cut soon, so I hope I can rack up some hrs on it.  The rings should seat by that time or I will send them back for a refund.  I did a M12 and M14 over last winter, and used NOS rings and the cylinders were also about the same.  Zero smoke from those.   

[prondzy 3,867]

you checked ring end gap and that's good, .010-.020 if im correct is spec, so it sounds like you are on the outer edges of the spec. When you measured for out of round of the cylinder how many places up and down the cylinder bore did you measure? and what was the difference between the pin sides of the bore and the thrust sides of the bore? The cylinder will wear greater at the top of the cylinder than the bottom of the cylinder that is why there usually is a spec for old bore and a new oversized bore. If you are only burning on the throttle up side, and governor kicking in  I guess that little bit of burn isn't much to worry about for a set of rings cheapies or OEM. 

[Fordiesel69 219]

Top and middle on the thrust sides of the wall.  I used snap guages and calipers.  Im sure a set of mics would be more accurate...

 

Old rings were NOT staggered correctly.  The new ones were.

Edited September 29, 2014 by Fordiesel69

[oldredrider 2,547]

Personally, I wouldn't worry about a little smoke until the rings seat. You know that it will be needing a rebore "soon" so roll with it until you decide to rebore. I don't think the rings are to blame.

[oldredrider 2,547]

On another note, I know you are using Rotella. Good oil...may take longer for the rings to seat since you are on the outer fringes of this bore.

[rmaynard 14,921]

What kind of rings were installed? Chrome or non-chrome. Chrome rings take longer to seat than non-chrome.

[Fordiesel69 219]

On another note, I know you are using Rotella. Good oil...may take longer for the rings to seat since you are on the outer fringes of this bore.

 

I only use the rotella t1 sae 30 in my 515 hrs 312 and 255 hr 314, the rest gets wolfs head sae 30 until I run out.  I used it in the engine in question for break in purposes. 

 

I think stens uses chrome.  I am not certain.

[Coadster32 793]

What kind of rings were installed? Chrome or non-chrome. Chrome rings take longer to seat than non-chrome.

 

X2 on this. Chrome plating is pretty hard, and will take a little while to wear, "seat" itself. I was going to mention about the orientation of the ring end gaps, but seems as though you have that covered as well.

[specialwheelhorse 174]

I see you are a ford man so I just happen to have a ford garden tractor Manuel

For tractors with Koehler engines and in the rebuild section it recommends 5

Five hours run in time to properly seat rings.

And according to kohlers Manuel the first half hour should be run in with

20 non d under some load then drained and another 4 1/2 hours with

30 non d then drain again and a fresh batch of 30 non d then should be good to go

I got about two dozen out here with that treatment and non smoke with non chrome

And chrome rings.

[Fordiesel69 219]

I see you are a ford man so I just happen to have a ford garden tractor Manuel

For tractors with Koehler engines and in the rebuild section it recommends 5

Five hours run in time to properly seat rings.

And according to kohlers Manuel the first half hour should be run in with

20 non d under some load then drained and another 4 1/2 hours with

30 non d then drain again and a fresh batch of 30 non d then should be good to go

I got about two dozen out here with that treatment and non smoke with non chrome

And chrome rings.

 

The only issue I have with that statement is that non d oil today is crap.  I cannot find it in my area except at walmart and it has API service SA.  This will not work in a kohler. 

 

The second issue is kohler has officially changed to recommend detergent oils across the board.  In an old dirty sludged engine, this indeed would be instant death.  But with this engine the internals were sprayed down and the oil pan was warshed. So it should still be ok should the proper intervals be maintained. 

 

I assume the rings are just taking some time, and frankly I have not been able to induce a heavy load on it.  I have mowed with it and lugged it down, but not the way I want to.

[Fordiesel69 219]

Got 4 hrs on it now, its getting better.  It does have a dirty exhaust when accelerating, but it is not blue anymore.  What I did find is that this magnum has the more rare (older) Carter style carb on it, which are typically not as emission friendly.  I am used to running the walbro models on the magnums which are significantly cleaner.  I may choose to swap over a walbro from one of my spare M12's to try it out.  

[oldredrider 2,547]

Generally, I believe they don't break in until about 8 hours. Give it a few more then try the carb swap.

[Fordiesel69 219]

If we let up on the rain soon, I will be able to do 4-5 acres which is about 4-5 hrs total with trimming around the stuff.