I have a D950 Kubota on a Jacobsen commercial mower. History: about 1900 hours, it over heated a couple years ago. Lost compression in one cylinder, pulled head, replaced piston and rings on bad cylinder, put together and ran good, until now it is getting harder to start. It mows and runs good if I can get it started. It puffs black smoke out while I'm starting so I'm sure its getting fuel. I pulled glow plugs and tested individually to see if they work. I checked and adjusted valve lash. Battery is strong. It doesn't start easy when it's hot, so I'm thinking its got weak compression on a cylinder or two. I need to find a diesel compressor tester. I assume it is tested thru the glow plug holes on an engine like this. One concern I have is, I check the voltage to the glow plugs while heating and it showed about 9 volts, does this sound right? Shouldn't I be getting close to 12V under load? Any help would be appreciated. Thanks.
Kubota D950 Help Needed - Compression Check
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Dave M7040
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Glow plug voltage is good assuming you have the Glow indicator on the dash. A glowing wire....
Compression using glow plug holes is correct.
Is the ignition switch original. Important because GP's need to be powered during cranking.
Proper ignition switch will bypass glow indicator while cranking.
Low compression will make starting difficult. Do NOT use ether!
Dave M7040
Compression using glow plug holes is correct.
Is the ignition switch original. Important because GP's need to be powered during cranking.
Proper ignition switch will bypass glow indicator while cranking.
Low compression will make starting difficult. Do NOT use ether!
Dave M7040
Dave M7040
Elite Member
- Joined
- Dec 10, 2012
- Messages
- 2,757
- Location
- Williamstown Ontario Canada
- Tractor
- Kubota M7040 Nuffield 465
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Check the air cleaner and the intake as well. A varmint nest could be there. The black smoke sounds like not enough air. Of course if there's inadequate air a compression test will fail, too.
Well, I did a compression check on it and I'm seeing 2 weak cylinders with one cylinder showing about twice the compression as the others. I'm going to back off the rocker arms and air pressurize the cylinders and see if I can determine whether its the rings, valve or head gasket, but either way I'll probably have to pull the head and see whats going on.