a 2005 Craftsman 4500YS
20hp B&S Intek Gold, model 31p977, code 0670e1
started a Saturday morning mow, and within 10-15 minutes... my mower was WAY down on power. By the time I creeped back to the shed... it seemed like it was barely going to make it. No surging like on and off fuel delivery though...
I pulled the spark plug... and it was fouled. oil fouled, not gas fouled. Very carbonized... I like carbon on fajita meat... not Champion plugs. I had not changed the oil this season, so I put in a fresh load of 30w and a filter, had a spare new plug on hand... slapped it in and am good to go... for... you guessed it... 10-15 minutes. WAY down on power... notice smoking this time in the exhaust.
Creep back to the shed. Pull the plug. Cuss then newly fouled new plug. Hoping for something fuel related... and knowing that I used the local quickie mart running whatever gas is cheapest last time (couple months earlier)... I drained all the fuel... head to a Shell for a few fresh gallons, hit the parts store for a couple more plugs (one to install and one to backup).
New gas in. New plug in. Power is back. For... can you guess? 10-15 minutes. It is a mild smoky return to the shed.
So gents... I can spin a wrench... just not really messed around in the small engine world. If I was to hazard a guess... I would say that I am down on compression due to a blown head gasket which is letting oil into the combustion chamber and fouling the plugs. The restored power comes from a fresh plug and allowing the engine to cool down and regain some of it's 'tightness' then as it gets hot, everything expands and starts the cycle to failure?... just guessing there.... and not sure if that is a hard job to repair. In the auto world, blown head gaskets usually mean lots of parts, lots of time, lots of cussing, lots of money, a couple of trips to the machine shop...
Is there something more obvious that I should check first? Are these symptoms caused by other things? (valves out of adjustment? stuck parts in the carb?)
thanks for the read and I appreciate the help.
<---- did you buy Cliff a beer?