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Curtis B.
Curtis B., Technician
Category: Agriculture and Farm Equipment
Satisfied Customers: 26038
Experience:  Technican turned service manager on multiple lines of equipment and rental equipment.
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My Kubota bx23 cranks but won't start. Any suggestions?

Customer Question

my Kubota bx23 cranks but won't start. Any suggestions?
Submitted: 6 months ago.
Category: Agriculture and Farm Equipment
Customer: replied 6 months ago.
My BX23 ran fine about a week and a half back when mowing about a 1 acre lawn. It began missing and ran rough loading it and unloading it off my trailer when I got home and wouldn't start the next day. It cranks, black smoke comes out exhaust, occasionally may "hit" but doesn't start. I'm stumped and I'm wondering if my injector pump is bad.
Expert:  Curtis B. replied 6 months ago.

Fuel quality? No gas could have been added to the diesel? If you loosen one of the high pressure injection lines at the head, and crank, is fuel squirting, or just dribbling? If just dribbling, remove the fuel shutoff solenoid in the link below, and see if engine will start. BX22 and BX23 are the same.

Customer: replied 6 months ago.
I have 3/4 tank of good diesel, new glow plugs, rebuilt injectors (by a local diesel shop), and with the local diesel shop on the phone, confirmed the engine is getting fuel (after cracking open the injectors), it's getting air (opened the breather tube), and took the fuel stop solenoid off - it cranks, puts off lots of black smoke & tries to "hit" occasionally, but won't crank. The diesel shop guy said he'd seen a hydrostatic Trans problem on an excavator malfunction & bog the engine down, not allowing it to obtain adequate cranking speed to start. What would you suggest next?
Expert:  Curtis B. replied 6 months ago.

Does engine seem to be spinning fast enough for start? Work the hydraulic controls and the hydrostat feet pedals to be sure that there is no hydraulic load on engine when cranking. When did engine last run? No problems then?

Customer: replied 6 months ago.
The engine seems to spin as fast as it always has - and I say it "seems" to, only because it never "spun" very much before it fired right up. I checked & rechecked the hydraulics and since the hydrostatic transmission has to be in neutral for the engine to turn over when starting, I didn't see a way it could be putting a "load" on the engine when I'm trying to start it. The guy at the diesel shop suggested I disconnect any driveshafts on the hydrostatic transmission, which I may try if my desperation continues. My BX23 has approximately 838 hours on it & the repair manual I have say the valves need adjustment at 800 hours. The manual explains how to adjust the valves in explicit detail - and since I've adjusted valves with solid lifters on gas driven engines of automobiles I've owned, the procedure looks to be much the same. Could the valves get so far out of adjustment that the engine, after mowing about 1-2 acres with no issues, began to run rough and fail to start the day after mowing? Tomorrow I've got the same 1-2 acres to mow and I'll either have to rent a mower or mow all that grass with a self propelled HONDA 21" push mower (which will be great exercise - but I'd rather mow with the tractor and exercise another way - Lol).
The only things on my "try this list" that's left is 1) adjust the valves, 2) put a few drops of oil in each cylinder by removing the glow plugs or injectors in an effort to "bump up" the compression in each cylinder, and if neither 1 or 2 get it to start, OR 3) find an adaptor for either the M8 X 1.0 threaded glow plug or an adaptor for the size & pitch of the injectors and get a diesel compression test kit (from Harbor Freight to try not spend any more money than I have to) - and hope that the engine doesn't need rings & bearing, and "IF" it has adequate compression in each cylinder and they're all "close" in their individual compression #'s, hope that I, or someone can help me figure this out and get my tractor running again.
Please let me know what you'd advise - thanks!!!
Expert:  Curtis B. replied 6 months ago.

Valves may need adjusting, and they do adjust as you know how, solid lifters, no surprises there. But that does not seem to fit problem. The last time I heard of this, it was caused by hydraulic load on the engine keeping it from starting. As for the compression, Harbor freight sells a tester that goes in the glow plug hole , if you want to test. Or rent one from auto supply. You say you opened the high pressure lines at the injectors, Was the fuel SQUIRTING? not just dribbling? Are the glow plugs getting full battery voltage to the common connection? Is the fuel return line open to the tank from the injector return line at the cylinder head? You have replaced both fuel filters and the electric fuel pump is working?

Customer: replied 5 months ago.
I checked & found that the valves did need adjustment. I'm not sure if the previous owner adjusted them or not - but the intake valve on the #3 cylinder was way too tight. It was so tight that it wasn't fully closing and when the piston in that cylinder fired it looks like it "backfired" to some extent (the air intake manifold was scorched on the #3 intake port). I'm going to pull the head hopefully tomorrow and see if I have damage on the intake valve in the #3 cylinder.
Also I removed the injector pump today and has my local diesel shop check it out and they said it had nomal wear but it functioned properly so it wasn't my problem.
So - can the valve problem on #3 cause a burned valve or carbon buildup such that I have inadequate compression? I'll probably take the head to the diesel shop or a local machine shop to be milled & have the valves checked out and/or replaced. Does it sound like I'm on the right track for getting my BX23 back in action?
Expert:  Curtis B. replied 5 months ago.

Could be. Did you try starting it after you reset the valves?

Customer: replied 5 months ago.
Not yet. I may try it tomorrow. But the #1 & #2 cylinders (with glow plugs removed) shoot air & diesel out of the glow plug holes with a lot of force and the #3 barely has any pressure at all. That's why I feel I have a burned valve or something.
Expert:  Curtis B. replied 5 months ago.

!! May very well be. Let me know the result. Thanks,