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B&S 12.5 HP I/C Gold - no compression

Randyry's Avatar
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05-15-02, 11:24 PM   #1  
B&S 12.5 HP I/C Gold - no compression

I picked up a Sears Riding Mower with a B&S 12.5 HP I/C Gold engine (model #286707, type #0441) from someone who said he replaced the crankshaft (thinks he ran it out of oil) but couldn't get it running after that and gave up. It has no compression at all - turns over easily in either direction by spinning the flywheel even with spark plug in. Tried a compression tester (turning it over with the starter) - zero compression. Pulled off head - blown head gasket, so I thought that's all it needed. Piston and valves seem to be moving ok and look ok. Replaced head gasket today, still no compression at all. With spark plug in, sometimes backfires through carb. Seems like timing may be off - could he have put it back together out of time when he replaced the crankshaft? Do I need to pull the flywheel to check that? How do I check for correct timing? Is it more work than it is worth? I don't have a manual for this engine and don't know how much time or money I want to put into it. Any ideas?

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cheese's Avatar
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05-16-02, 12:26 AM   #2  
Hi Randyry!

It could very well be out of time. When the crankshaft is replaced, it must be timed with the camshaft. If the alignment marks were not aligned, it won't be in time. Backfiring through the carb would be an indication of this problem. You can fix it, but engine removal is necessary. It's not difficult, and we'll help guide you through it. I do suggest a service manual. Autozone carries small engine manuals that should cover this engine, and Walmart carries Briggs manuals, which is preferred.

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