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Case 646 rescue
Posted: Thu Jun 12, 2025 2:46 pm
by Harry
I ran the rear mower this morning and it worked fine. The travel speed was good until it heated up then it was a little slow. Knocked down some tall weeds that were about 2’ tall. Decided to till a little with the Troybilt. I usually run it slightly above idle. I did half the garden and suddenly it stopped. Tried to pull start it and it turned over very easily which meant no compression. This tiller is very hard to push for grandpa, so I ran the 646 out to pick it up with a strap. Got it up to the shop pulled the spark plug and no compression. Pulled the valve cover and the the retainer in the top of the spring came off the valve stem. How random is that? One step forward two steps back.

Harry
Re: Case 646 rescue
Posted: Thu Jun 12, 2025 4:45 pm
by MattA
When I clicked on this thread, I thought you got the 646 stuck
Did you get the tiller fixed ok?
Re: Case 646 rescue
Posted: Thu Jun 12, 2025 5:05 pm
by DavidBarkey
Harry , the rocker backed off and the lash got so bad that the slapping of the valve dislodged the keeper. seen it before on a B&S.
Re: Case 646 rescue
Posted: Thu Jun 12, 2025 5:14 pm
by Harry
Actually the keeper is in the retainer. Compress the spring and slide retainer on valve stem. Release spring and it locks in place. Closer look shows broken pushrod guide and broken headbolt. Harry
Re: Case 646 rescue
Posted: Tue Jun 17, 2025 9:32 pm
by Harry
Installed new plate but then the decompression of the cylinder wasn’t working right so hard to turn over. Reset valve lash a little better but still wouldn’t start. Checked spark at plug by grounding and turning over, no spark. Not sure if crank sensor is bad or coil. Not in the mood to check it out anymore so pushed it into corner. Needto get garden planted.

Harry
Re: Case 646 rescue
Posted: Tue Jun 17, 2025 10:22 pm
by JSinMO
Harry wrote: ↑Tue Jun 17, 2025 9:32 pm
Not in the mood to check it out anymore so pushed it into corner.
I can relate to that statement. Sometimes it’s better to shove a project in the corner and revisit it later.
The broken head bolt is kinda surprising. I’m sure you’ll figure out the spark issue when you get back to it.
Re: Case 646 rescue
Posted: Wed Jun 18, 2025 7:09 am
by Harry
JSinMO wrote: ↑Tue Jun 17, 2025 10:22 pm
Harry wrote: ↑Tue Jun 17, 2025 9:32 pm
Not in the mood to check it out anymore so pushed it into corner.
I can relate to that statement. Sometimes it’s better to shove a project in the corner and revisit it later.
The broken head bolt is kinda surprising. I’m sure you’ll figure out the spark issue when you get back to it.
Spike, it ran fine before the valve spring came loose. I just wanted to get the garden ready for planting. Pull the head off later and replace the bolt. With the 444 not running I’m thinking putting the till on the 646 and finish the garden.

Harry