B&S 28N707-0141-01 woes :(

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  #1  
Old 08-13-06, 06:33 PM
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B&S 28N707-0141-01 woes :(

Newbie here.

Engine is about 4 years old. Ran fine for 3 years of light lawn mowing duties. Last year the engine got noisy and eventually lost power and smokey. Took off the valve cover and the posts had unscrewed. Tightened them up and the engine was fine again. Kind of. It was now difficult to start, and only now am I understanding that it was probably a result of high compression. It needed a jump start even with a new 275cca battery. Anyway, the engine ran fine for another year.

Today the engine lost power and huge smoke out of the muffler. Checked the valves again - they are fine. The engine would sometimes start, but straight away it had no power and huge smoke out the muffler, and cut out after a few seconds. Did that a few times and then a nasty noise from the starter gears and the engine won't turn at all. Starter turns, gears don't mesh.

Took off the starter gear cover and the gears are well chewed and a few missing teeth. Same for the flywheel gear. So I know I need to replace those, but what about the high compression and smokey muffler?

Took out the head bolts and took off the head (28N707 is OHV single). By the way, both bolts holding in the muffler sheared off The head gasket is perfect. Engine is easy to turn. Bores are not ridged and look great. This looks like a good candidate to fix and get a few more years out of.

My thoughts - get a new head gasket and reassemble the head. Remove flywheel and replace the plastic gear with the new aluminum kit. Neither of which will solve the high compression problem.

General question - how is the valve gap adjusted? There is no adjuster. What causes the engine to develop high compression, and what is the fix? Would this also cause the smokey muffler, or is that a different problem? Also, the oil is getting pushed back into the air filter and that is a big mess too. Do these engines have crankcase breathers?

Specific question - can someone provide the part number for the head gasket? Also, is there a way to get off the big center nut that holds on the flywheel without buying the $32 B&S holder tool? If I have to buy the tool, what is the right part # for this engine - 750-083 or 750-075?

Thx for your help!
 
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  #2  
Old 08-13-06, 08:24 PM
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Sounds like you probably had either a blown/leaking head gasket or gas in the oil. The valves do have adjusters. There is a torx set screw in the center of the adjuster nuts. Set both valves at .005" with the engine a tad past TDC. The flywheel nut will come off easily with an impact wrench.
 
  #3  
Old 08-14-06, 05:22 AM
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I've seen the torx before and tried to move it but it was stuck solid, and I assumed it was not adjustable. Thanks!

So far I have:

B&S part # 696537 flywheel ring kit (aluminum)
B&S part # 273280s head gasket

Not sure about the crankcase breather. There is a hose (# 691328) but I didn't find a valve.
 
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Old 08-14-06, 09:48 PM
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You usually have to get the nut loose before the torx set screw will turn. If it won't break free, you may have to replace the adjuster.
 
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