Somewhat new but willing to put the work in. Here is the story behind the mower:
The mower was working great and all of a sudden chugged loudly at a reduced very low RPM. I checked the oil (which was very low) and added oil. Pulled cord and continued to chug loudly and at a very low RPM. After a few starts the pull cord would build up compression and be super hard to pull. With constant force it would eventually release and rotate a couple spins before building up compression again.
Things I've tried so far:
- Removed the starter coil housing to make sure the rope pulls freely when disengaged from the engine. It does.
- Checked that the flywheel nut key looked intact - was able to remove the flywheel nut but not able to remove flywheel. Key looked like it was good.
- Checked that there is enough gas and gas was flowing.
- Removed all oil and added 12oz of fresh oil.
- Checked that nothing is stuck in the blades and cleaned bottom of deck.
- Cleaned carb
- Removed the spark plug & pulled the cord a few times to see if there was oil in there -- nothing came out. The cord pulls easily and completely when the spark plug is out. As soon as I put the plug back in, the problem reoccurs.
- Replaced spark plug. Prior plug end was covered in black soot.
- Checked the filter. Little dirty but serviceable. Also tried to start with filter off.
- Adjusted valves to .1mm
After the valve adjustment the the cord initially pull fine but couldn't get the engine to turn over (might have chugged a couple times before dying). After about 10 pulls the compression problem returned.
Just try to remove the flywheel. Even if the nut key looks OK, without removing the flywheel = nono. Had the same problem with a push mower with a (think) GCV 160 engine. After the flywheel removed, I saw the damaged key. Greets.
The gcv160 has a plastic camshaft pulley and a rubber belt to time the valves. You would have seen it when you adjusted the valves. Take a good look at that pulley and see if it is damaged. I think it also controls the compression release function. That might answer both the poor engine performance and the stuck compression.
