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I had a mower that had a compression release spring problem on the camshaft detailed in the following fixit question: Craftsman tractor engine compression or timing issue I had the mower running for a whole season but it got worse so I decided to strip it down and indeed the compression release spring was in pieces inside the engine case. I installed a new camshaft (changed out the oil gov and all seals rebuilt the engine and it started up first time with no compression or turnover issues at all. See Below: https://youtu.be/DKcggQdvAwc I then left it for about a month, went back and it started again first time. I let it run for a while and all was good. Then the next time I came to start it I forgot to turn the fuel cut off valve on and so it ran out of gas and stalled after a minute. I turned the valve on, and got it started but then it began to run rough and now won’t start at all. I thought it was still fuel starvation but checked the carb and was letting fuel through fine. Checked the spark plug and it works fine - did smell heavily of gas when i removed it. See vids below - any thoughts? Has the timing gone? https://youtu.be/q_WvfPjqkm4 https://youtu.be/gSHX2qpLcBk I stripped down the carb, all looks good. Spark plug working good and valve spacing is all good. Here is another video of it trying to start and the good spark plug. https://youtu.be/8hKMRK0e0QU Update: I stripped down the cylinder head - lots of carbon build up. Cleaned that out and piston head, replaced head gasket, checked valve spacing, stripped carb again, checked bulb solenoid, replaced spark plug and checked it is firing from the coil when out of engine, replaced with fresh gas and…..still no luck: https://youtu.be/ZHnuWQz8IhY I’m lost for ideas unless something has failed inside the case somehow, but can’t think what….
Have you checked the valve seats when you replaced the head gasket? Also did you reset the spacing of the coil arms using an index card? The timing is usually controlled either by a key on the flywheel or electronic points underr the flywheel. Usually loss of compression could be cause either by blow by on the piston or leaking valve or seat ..
Without long explanation, try injecting a little like 2 mls motor oil through plug hole spin by hand place plug and see if start. Sometimes oil comes off rings via overfueling, lean burn etc.
Way old post but has anyone gotten anywhere on this?
Hey Anthony, in the end my problem was actually the flywheel key!! I discounted it early, but when I went back and looked at where the piston was at spark firing realized it was off. Turned out all my work made the engine run really well and very clean (pretty much rebuilt the engine twice…) but the actual problem this time was a $2 part…
