B1700 Compression Test

[nick95rs]

I got around to doing a compression test on my Kubota. It's not looking good. It only has 530 hours on it. I bought it two years ago, so I dont know the history before I got it. Well on to the results. Number 1 cyl. 340, number 2 cyl. 200, number 3 cyl. 360. Is there a way to make sure it is rings and not a valve problem without pulling it apart.

I do want to try and do the work myself. I have done work on plenty of cars before. Not much internal, but a couple of head gasket swaps. They were all on gas engines though. No real experience with diesel engines. I would appreciate any insight on my next steps. Thanks

Nick

 

[naildriver111]

I got around to doing a compression test on my Kubota. It's not looking good. It only has 530 hours on it. I bought it two years ago, so I dont know the history before I got it. Well on to the results. Number 1 cyl. 340, number 2 cyl. 200, number 3 cyl. 360. Is there a way to make sure it is rings and not a valve problem without pulling it apart.

I do want to try and do the work myself. I have done work on plenty of cars before. Not much internal, but a couple of head gasket swaps. They were all on gas engines though. No real experience with diesel engines. I would appreciate any insight on my next steps. Thanks

Nick

Squirt a little oil in the cylinder and re-check compression, If compression goes up then it's the rings.

 

[ibnxe]

I would also suggest that you check the valve adjustment. A tight valve could result in a lower than normal reading. 530 hours is just getting started... hope it isn't too serious.

 

[nick95rs]

Thanks guys. I will put a few drops of oil in the cylinder and retry. I have read a little about adjusting the valves on the Kubota engines. Anyone know if there are marks on the flywheel of the D905. I don't have a WSM, I will get one if I have to go into the engine though. Thanks again for the info.

Nick

 

[nick95rs]

I put a few drop of oil in the cylinder with the lowest reading. It went from 200psi to about 360psi. I guess that tells me that it is the rings. I guess now I will have to do a rebuild. I hope that I can do just rings and gaskets. I don't really want to have to take the block to a machine shop, and buy new pistons. Let me know if any of yall have any first hand experience with rebuilds.

 

[naildriver111]

My only engine rebuilding experience was on a sb Ford 302 in my 76 Bronco. But the most important tip I was given can be used on any engine rebuild... "Take pictures" of every step during disassembly, It really helps when you put it all back together, especially pics of how the rod cap, rod bearing should be turned. Also, the rings will have dots at the gap and they should face up when installing.

 

[mjw357]

Not familiar with your engine/tractor at all. But you may be able to drop the oil pan and get that one piston/rod out through the bottom. If it's just a broken ring and there is no damage to the cylinder, replace rings and back in. Like naildriver said, be sure to get the bearing caps back EXACTLY how they were before you started, mark everything you disassemble.

 

[Yandaddy1110]

For what reason did you do a compression check in the first place? Was there a problem?

 

[nick95rs]

I explained my problems a few weeks ago in another thread. I was having problems cranking it. It still runs great once it cranks. I'm surprised the compression is that low in that one cylinder really, considering how good it does run.

I am hoping that I can do everything with the engine in the tractor and not have to take it out. I will take plenty of pictures and mark everything good. I had not thought about marking the caps, but I know that you are suppose to so they go back in how they came out. Thanks for the tips.

 

[BleedingOrange]

Have you considered adding some ring free, or some other additive in case you have some rings carboned up and stuck. I would try that before disassembling anything. If the hours on your tractor are accurate, that engine is hardly broke in. Talk to a dealer and see if they have seen this problem before with such low hours. Try some ring free, and re-test your compression. Please let us know how you make out.