Lack of Compression on a Kubota one cylinder

[Charlie]

Ok I finally got it running. I opened it up to check the rings and ended up breaking one as I took it off. You couldn't purchase the one ring so I put a new set on. Also had the head gasket on the wrong way (man am I embarrassed) not sure which was the real problem but I got a 98% leak down test but the compression never went as high as it was supposed to. It starts easy though. I'm going to run it for a half hour before installing it back on the boat.

[DeepFrz]

I'm glad you got it going.

[Compass790]

Good stuff getting it running. If you didnt hone the cylinder before putting in the new rings it might take a while for them to bed in but basically if it starts easy i wouldnt worry about it. You could check the compression again after about 50 hrs out of curiosity

[Charlie]

I don't have a working knowledge of how much a difference there is in between a cold engine and a warm engine for the compression numbers. when I squirted oil in the numbers climbed substantially. BTW i did hone it a little even though it was not glazed.

[Compass790]

Yep a squirt of oil makes a big difference. In the Yanmar it goes from 300psi without oil to 400psi ( cold) with but the liner has a noticeable step in it where the ring travel ends so the liner is very worn. I too broke a ring trying to get the piston back in. Aaargh!
Paul

[Farr50PH]

Hi Jim and Charlie, can you share the "hose removal tool" information? I am trying to remove ~2" cockpit scupper hoses. (I am also troubleshooting hard start, low compression on Kubota EA300. Looking to order the glow plug adapter and buy a diesel version compression gauge.)
Thanks,
Ben

[Diesel Bill]

For sealing the head gasket I recommend a spray called " Spray Tack " sold in auto parts stores. Works great on all gaskets.

[Saltyhog]

I'm guessing it's something like this. https://www.amazon.com/Tool-Aid-1386...J4B2BF4TKGXZ4Y

I have one and find it useful in lots of applications.