Cub Cadet SR-621 12A-979I100 NO COMPRESSION.

humblegeo

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Had this mower about 10 years and was going strong untill I tried to run some old old filtered fuel thru it. Big mistake. Long story short, I wound up removing the carburetor and cleaning it as well as flushing out the fuel tank, new spark plug, replaced the fuel line. Now when I try and pull start it, it's like it has no compression at all and wont start. Almost like there is a compression release that is stuck open or as if the spark plug is removed?? Really weird. Does anyone know if this self propelled model has a compression release? If not then It may be a blown head gasket but I don't see how, it just sputtered and sputtered with the old fuel till it wouldn't run at all. Appreciate any help or advise.
 

briggs

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could be a stuck valve i have seen that happen
 
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possum

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Old crappy fuel can gum up just about everything on an engine. Old crappy e-10 is even worse. I have seen a couple cheapo string trimmers that were just sticky gunky mess inside after a couple tankfulls of old two stroke fuel. Then some folks never have much trouble. Ya just never know . I saw a lawnboy a couple years back that had old fuel mix in it and the oil had sort of turned to contact cement consistency and not quite as sticky. The gas was all gone.
 

Mpollock

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I agree with possum - using old oil in your mower (even if it is filtered) can gum pretty much everything up. I haven't personally worked with a Cub Cadet mower before so I can't really comment on whether it has a compression release or not, but from my past experience I would hazard a guess that the oil has probably mucked a few things up in your mower's internals. If you give your ideas a go and still can't figure out what's going on it's probably best to just replace the mower (it is 10 years old after all), as getting it professionally fixed will probably cost you a bit.
 

humblegeo

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It was a suck inlet valve. I guess the bad fuel must have deposited gunk on the valve stem and caused it to stick open. I removed the carburetor and used WD40 to spray into that area and managed to work it loose. Appreciate the help.

 

briggs

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It was a suck inlet valve. I guess the bad fuel must have deposited gunk on the valve stem and caused it to stick open. I removed the carburetor and used WD40 to spray into that area and managed to work it loose. Appreciate the help.



New it was a stuck valve 90% of the time that is what causes no comp glad u got it fixed
 
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