B 1700 Hard start, black smoke pouring out exhaust

03marauderman

Member

Equipment
Kubota BX 23S
Sep 27, 2018
69
1
8
Plattekill
Have a B1700 with about 900 hours that can almost crank a battery dead before firing when cold......Will start OK at operating temperature, but overnight hard start. I'm puzzled by the black smoke coming out the exhaust while cranking ???
 

Roadworthy

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Lifetime Member

Equipment
L2501 HST
Aug 17, 2019
1,649
525
113
Benton City, WA
As a first step try cleaning the air cleaner and make sure there are no obstructions between the air cleaner and the intake manifold.
 

Dave_eng

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Lifetime Member

Equipment
M7040, Nuffield 465
Oct 6, 2012
5,107
926
113
Williamstown Ontario Canada
Sounds like the glow plugs are not working.

Does your glow indicator light up?

Has anything been changed on the tractor's wiring, a new key switch, wiring,?

Do you have a 12 volt test light? it is a very basic trouble shooting tool.

Test light.jpg


Dave
 

03marauderman

Member

Equipment
Kubota BX 23S
Sep 27, 2018
69
1
8
Plattekill
Actually the tractor isn't mine..it belongs to a widow who has been mowing herself the past several years...I did ask her if she ever used 'either' - she asked 'what's that'?...so that was a good sign....I did pull the cover on the air cleaner to see if some mice made a nest, it was debris free, but didn't go further, & yes the glow plug light does come on...Nothing has been changed or tampered with...quite honestly it most likely needs a service....I just want to gather some idea's before going back out there......Thanks for your suggestions......
 

Russell King

Well-known member

Equipment
L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
4,603
975
113
Austin, Texas
The injectors may be leaking fuel into the cylinders and making it too loaded with fuel to start easily and the excess fuel not burning well when it starts. Does it clear up after running?

You can replace the injectors but get from Kubota or reputable sources not eBay or amazon. There will be sealing washers or rings involved also
 

03marauderman

Member

Equipment
Kubota BX 23S
Sep 27, 2018
69
1
8
Plattekill
Yes it does clear up after starting...So there's really no way to diagnose it other than change the injectors?, also once it has been running & shut it down for a couple of hours it restarts fine like there's no issue...I agree no aftermarket.....always OEM..... Thanks
 

SDT

Well-known member

Equipment
multiple and various
Apr 15, 2018
3,084
923
113
SE, IN
Have a B1700 with about 900 hours that can almost crank a battery dead before firing when cold......Will start OK at operating temperature, but overnight hard start. I'm puzzled by the black smoke coming out the exhaust while cranking ???
Unrelated to your original question but useful information.

Starter motors are intermittent duty motors not suitable for continuous duty.

One should never operate a starter motor for more than 15-20 seconds without providing a substantial cool-down period.

Also, a diesel engine will start more slowly (or not at all) if cranking speed is slow. Battery, cables, etc., need all be as should be for proper starting.

SDT
 

03marauderman

Member

Equipment
Kubota BX 23S
Sep 27, 2018
69
1
8
Plattekill
I do understand that the starter should not be cranking till it starts, but with this situation there's a tendency to over crank it....There is also the consideration of the operator, she might not have all the instincts of a mechanic....She checks the oil, fills the diesel tank & away she goes....Bless her that she can mow...I appreciate any comments, as they serve as reminders....Thanks
 

Russell King

Well-known member

Equipment
L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
4,603
975
113
Austin, Texas
There may be other things to do before replacing the injectors.
Insure the glow plugs are getting warmed before trying to start.
Insure the starter is spinning to speed by having it tested or rebuilt (I was amazed at how much faster my tractor spun with a new starter).
Are you using a decompression knob to let it spin easily up to speed? Do you know the proper starting procedure for the tractor and is it being followed?
 

03marauderman

Member

Equipment
Kubota BX 23S
Sep 27, 2018
69
1
8
Plattekill
'Decompression knob".??? The topic of the tractor came up on an unrelated visit, I had no clue that there was an issue....thus was completely unprepared other than opening up the air cleaner, & a brief attempt in cranking....What I found unusual was the thick black smoke coming from the exhaust.....That's what got my attention....The glow plug light was working & I attempted to start it like mine....but I know when to release the key....Not going any further I posted for idea's & suggestions....The 900 hours is another factor, Removing the glow plugs opens up the opportunity for a compression check.....Even with gas engines compression sure clears up a lot of mystery.....I was just reaching out for something that wasn't obvious to me, or a concrete answer to the black smoke while cranking.....Going to have to load up the tool box, pack my lunch & spend the day..... Just kidding...I'll get fed....
 

BruceP

Well-known member

Equipment
G5200H
Aug 7, 2016
835
353
63
Richmond, Vermont, USA
My 2cents --- The symptoms SURE sound like either weak battery or some of the glowplugs not heating.

*) Monitor battery voltage WHILE glowing and cranking. (should never drop below 10V)
*) The easiest thing to try is DOUBLE-glowing to see if this improves the situation.
*) The next thing I would test is for voltage at the GPs whist glowing.
*) After glowing (but before the first start) you should be able to feel with your fingers each of the GPs and expect a slight amount of warmth on each one.