Cylinder pressure after rebuild question

[jjdike-HT]

Hello,

I have a YM240 in which I have just replaced the sleeves, pistons, rings, head gasket, and had a valve job done for the head. I'm testing cylinder compression now. I'm only getting 250 psi in each cylinder, but that is with about 3 cranks, after which my battery is unable to turn the engine more. I think the battery is in good shape, just recharged and voltage seems ok. Any suggestions on how to determine if something is leaking or is this mainly a get a new battery issue first?

Thanks
Jay

 

[winston-HT]

With 250 psi compression and only 3 turns you either have a bad battery or starter components problem. Your battery should be reading at least 12.6 volts. Have you checked all the components out? I am assuming no problems with engine as for as trying to lock up.

 

[jjdike-HT]

Hi Winston - thanks for the reply.

I connected a larger battery and got several turns out but not an increase in pressure. The voltage of the battery I first used is 12.8 V.

I replaced the starter a long time ago - maybe 15 years ago. It does seem to turn over easily with the injector ports open, which maybe doesn't add a lot of information. I can also turn the engine over by hand since the front crankshaft nut is accessible. It feels like the pressure bleeds off when I crank manually and have the pressure gauge installed though so no pressure build up. Maybe it's a similar issue when cranking with the battery - the last cranks are relatively slow so perhaps unable to build up more pressure?

I did just reassemble this so it's possible not everything is getting lubricated fully since it has only been turned a dozen times or so, possibly making it harder to turnover. However It is relatively easy to turn by hand (with ~15" ratchet length on the front crank nut).

If I was to replace the starter is there a big difference in torque/power between the HSM-2000USA and HSM-2000GR? I don't use the tractor very often to justify a big difference in cost but do want it to start when I do want to use it.

 

[winston-HT]

I see Hoye gives the starter a good review. https://www.hoyetractor.com/PROD/SM-2000GR.htm

I'm assuming you haven't been able to get it started since rebuild. If that is the case, have you made sure your air is bled out all the way to the injectors? Are you using the compression release to get fast rpms when trying to crank?

 

[jjdike-HT]

I haven't put it together enough to try to start it - mainly not installing the injectors - so not much left to do.. I wanted to check out the cylinder pressure before completely reassembling everything as a check along the way. Just to save time if something didn't seem right and saving some time in taking it all apart again to fix something.

 

[winston-HT]

Probably bad advice but I would button her up and go for it.