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Craftsman 21" self propelled, B&S 7hp OHV, smoking


gutterback's Avatar
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09-14-10, 05:24 PM   #1  
Craftsman 21" self propelled, B&S 7hp OHV, smoking

This mower is several years old and has begun to smoke very badly. The engine model is 128602-0304-E1.

Since it is close to the end of season here my questions are..

What are your experiences with this engine? What normally do you see causing the oil burning?

Should I consider tearing it down an rebuilding this winter?

Buy a drop in replacement?

Wait for the snow to fly and buy an new mower half off at the
box store?

Thanks

 
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09-14-10, 07:02 PM   #2  
Hello gutterback,

What are your experiences with this engine?
Everything.


What normally do you see causing the oil burning?

Worn rings from dirt ingestion due to neglected/nasty/improperly installed air filters and lack of oil and or proper oil changes.

Should I consider tearing it down an rebuilding this winter?
IMO, Not worth the time/money.

Wait for the snow to fly and buy an new mower half off at the
box store?
IMO, Best way to go and will give you not only a new machine but warranty as well.

 
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09-29-10, 04:53 PM   #3  
Thanks for the input

I took your advice and bought another mower. Curious to see if I could determine the problem I took the head off and examined the bore. It is clean without any noticeable surface defects. The valves have heavy buildup.

Does this change your opinion on doing a rebuild?

Thanks again

 
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09-30-10, 08:36 AM   #4  
Was the oil over filled, did you check the compression before you pulled the head, it could be excess wear of the valve guides that is letting oil into the combustion chamber, also if your mowing or storage practices have changed where oil can pool in the valve cover would increas the chances of valve guides leaking. Have a good one. Geo

 
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09-30-10, 05:02 PM   #5  
Rest of teardown

I took the piston out and it looks good also. I then took the valve assembly apart and it does appear that the guides are worn. I won't know for sure until i can get my calipers home but they feel like they have quite a bit of clearance, especially the exhaust valve. Anyone know the normal diametrical clearance between the stem and guide?

 
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09-30-10, 05:28 PM   #6  
Posted By: gutterback Anyone know the normal diametrical clearance between the stem and guide?

Hello gutterback,

Here's the clearance specs your seeking;





I would suggest checking all to assure a proper long lasting rebuild should you proceed that direction.


Good Luck

 
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