I have an 8 year old Scotts riding mower (built by John Deere) with the base 17 hp single cylinder engine. A while back I started having a problem with the starter. With a fully charged battery, the starter would engage and begin to spin the engine but would stop at full compression. It seems like the starter is weak or maybe there is a compression release mechanism that is not working. If I manually spin the flywheel to a no compression area and then hit the starter it will spin the engine (like a running start) and get over the compression hump and start the engine. When I turn the flywheel by hand I notice that the compression is very strong, that is why I was wondering about a compression release not working. Do starters become weak with age? Anyone have any ideas about just what is going on here?

quick way to check, take the spark plug out and roll the motor over, if the starter rolls the motor over really easy and fast, than I would definatly say that your compression release is not working properly, if it rolls it over slow, and seems to have a hard time spinning, thatn I would have to say your starter is going bad

Yes, it works fine as long as there is no compression. How does the compression release work on this model? I don't notice anything engaging when trying to start.

Could just be a simple valve adjustment. What is the model, type and code numbers of the engine on your unit??

hey pt,

my father had the same thing going on with his and we took it in and they said it was a valve timing problem, they said this was a normal thing it cost about 100.00 to fix. anyhow just was wanting to give you some input too the problem. i hope you can get it fixed.:wave:

Richard

hey pt,

my father had the same thing going on with his and we took it in and they said it was a valve timing problem, they said this was a normal thing it cost about 100.00 to fix. anyhow just was wanting to give you some input too the problem. i hope you can get it fixed.:wave:

Richard

If the engine has not been apart, the the valve timing should be alright. It's likely just the valve lash adjustments, which is a normal maintenance item. If you have too much clearance then the compression release will not operate and the compression may be too much for the starter to overcome. Continued operation or attempts to start with this condition, can result in starter failure.

Have the battery load tested. It may show full charge but will not have the cranking amps to get past the compression stroke of the engine.(Seen this many times) If the battery checks out OK, check the simple things first, check cables, check connections, and check for good ground. If they are all good then go after the valve adjustments.

Could just be a simple valve adjustment. What is the model, type and code numbers of the engine on your unit??
this is very likely also, I forgot about this issue

Thanks to all for the comments.

It could be the valve adjustment, because it probably needs it. I'm sure it's not the battery, because it's brand new and topped off with a computer charger to be sure. Ground connections are all good. I don't feel confortable doing the valve adjustment myself so I will take it in for service after the mowing season.

I should also mention that I had some gas coming out the muffler once I got it to run, but that could be from flooding the carb from rotating the flywheel many times by hand while trying to get it to start.

If the carburetor is leaking fuel, this can also cause a problem cranking, liquid in the cylinder can cause excessive compression as well.