Kubota L35 Hard Starting When Cold

LeanGreenMan

New member

Equipment
L35
Apr 30, 2026
5
0
1
Colorado
I have a 2001 L35 with about 1100 hours on it. I purchased it a couple years ago, history unknown, I have done a bunch of repairs (mainly fixing hydraulic leaks), and have put about 200 hours on it.

Recently it has become challenging to start when in the 30s or 40s F. Granted the block may be colder from sitting overnight. I have a service manual and I can't find anything on what the glow plugs are supposed to read on an ohm meter. All my glow plugs read roughly 1.6 ohms. The glow plug controller seems to work properly as I don't have the light randomly turning on, when the tractor is hot it only lights for a second or less, and when the tractor is cold it lights for maybe 5 seconds.

To get the tractor started when cold, I now have to give it full throttle with the foot pedal, cycle the glow plugs, crank a few seconds, fail to start, and repeat the process a second, sometimes a third time. Once it catches I let off the throttle and while it may run rough for a second or two it then runs smoothly. On initial start it blows a cloud of smoke, mostly black, a little bit grey, but clears up within a second or two.

This is contrary to how it worked a year ago when generally it would start first try when it was in the 20s outside and didn't require any throttle past idle.

I do have some vapor coming out the CCV tube when it is running, I think it may be more when hot, but it is not enough that I smell oil while it is running. Oil level is stable, although I guess it's possible that oil and diesel are mixing at a rate to keep the oil level stable... I doubt this, but it is possible. I run 10W-30 oil as speced by the manual. The vapor may be greater than it was a couple years ago, I don't know and I don't have a compression tester. The exhaust doesn't smoke except as noted on startup and if a lug the engine doing loader work - in that case it will smoke black.

Valves have not been adjusted to my knowledge. That is one of the things on my todo list. It is important to me that this starts reliably when it is cold out. One of my next improvements will be to add a quick tach so I can utilize a pusher box to push snow. I will get a magnetic block heater, but I do not want this to be reliant on the block heater when cold.

Any advice is much appreciated.
 

Nicksacco

Well-known member

Equipment
Kubota L35 TLB, 2014 RTV-1140CPX
Sep 15, 2021
762
499
63
Bahama, NC
Have you checked the injectors?
The injectors are very easy to take apart and clean.

A problem with something downstream such as fuel filter, water in diesel could also be the issue.
Is the battery able to spin the engine over quickly?


 
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#40Fan

Well-known member
Jul 21, 2022
519
367
63
USA
Even though the light on the dash is coming on, confirm you are getting power to the glow plugs.
 
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Russell King

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Lifetime Member

Equipment
L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
7,497
2,831
113
Austin, Texas
I don’t think the magnetic heater will help much and the oil pan is probably cast aluminum.

You may want to add one like this (use as reference only - I don’t know how to find the exact L35 part).

BUT if it didn’t need it in the past I would get the glow plugs checked out first.

IMG_0658.png
 
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Hugo Habicht

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Lifetime Member

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G1900
Jun 24, 2024
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Ireland
Check / adjust valve play first. Then check current is flowing into the glow plugs using an ampmeter. You wrote you have checked the resistance, but measuring the current covers everything (cables, switches etc.).
 

L35

Well-known member

Equipment
L35/TL720/BT900/York rake/Valby chipper
Jun 13, 2010
684
787
93
CT
FWIW I have about 1400hrs and no blowby out the draft tube.
 

LeanGreenMan

New member

Equipment
L35
Apr 30, 2026
5
0
1
Colorado
Check / adjust valve play first. Then check current is flowing into the glow plugs using an ampmeter. You wrote you have checked the resistance, but measuring the current covers everything (cables, switches etc.).
Yeah, planning on getting to that later today. Trying to run the last of my topsoil through my grizzly so I can get seed down before it is too late...
 

LeanGreenMan

New member

Equipment
L35
Apr 30, 2026
5
0
1
Colorado
FWIW I have about 1400hrs and no blowby out the draft tube.
I had virtually no blow by when I picked this tractor up. It is worse now. I can't figure out what is causing it. I religiously clean the air filter, I do not see any possible dirt/dust intrusion spots, and I have no oil consumption... I just checked that, still exactly where it should be, and it doesn't smell like diesel.
 

LeanGreenMan

New member

Equipment
L35
Apr 30, 2026
5
0
1
Colorado
Well ladies and gentleman, bad news. Pulled the air filter out, pulled the clean side air intake hose off, and there is a little bit of dust in there. Not sure where the dust intrusion is coming from. It appears once upon a time a mouse or something must've chewed up the air filter (before I owned it), as the supports inside the filter housing have been chewed on. I'm not sure if this is dust that has been in there since that incident, or what. I am slightly concerned my air filter isn't sealing tight against the housing. I don't know why that would be as the screw for the cap gets progressively tighter as I screw it down which suggests the air filter seal is being squeezed as designed.

While this may be a valve issue, or fuel issue, or glow plug issue, I am now very concerned it is a compression issue. I'll see if my neighbor has a compression tester when he gets home. If not, I'll order one. Before I start chasing a bunch of stuff, I guess I need to make sure I don't need to rebuild or replace the engine.
 

Hugo Habicht

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G1900
Jun 24, 2024
1,481
2,129
113
Ireland
I hope it's not a bigger problem.

But if compression is bad you should check valve play as well, this may be a reason for it. And do not forget to check the glow plugs from getting current. This would be the most common cause for a poor start.