diesel runs rough on start-up

[jbarker855]

I have a 2004 John Deere 4120 with a 4 cylinder turbo diesel. The problem is that when I start it after it has been sitting for a few days, it runs very rough for about 5 seconds, and then clears up and runs good. In that first 5 seconds or so, it sounds like it is starving for fuel, and sounds like it wants to stall. It acts like my other diesel sounds when I have almost run it out of fuel and there is a little air in the lines that needs to be bled out. If I restart it later that same day, it runs fine. There is no stumble or rough running.
This tractor starts every time, and does not stall out, but I suspect this initial rough running is not normal and I want to fix it before the problem gets worse.
Any suggestions? Thanks in advance!
-Jay

 

[Soundguy]

do you see any dark dust collecting around any of the injectors or injector lines?

soundguy

 

[RoyJackson]

Did you use the glow plugs prior to starting? It's probably getting a bit cool in New York state...

 

[jbarker855]

Roy-
It is getting cold, but my 855 starts up good even without the glowplugs. And the indicator on the 4120 is not even lighting up to suggest that it wants me to pause to let the glow plugs warm up. Also, this problem was present even a few months ago when it was warm.
Soundguy-
I will check the injectors. Sounds like you suspect a small leak which is bleeding off presure/letting in air?

 

[RoyJackson]

Roy-
It is getting cold, but my 855 starts up good even without the glowplugs. And the indicator on the 4120 is not even lighting up to suggest that it wants me to pause to let the glow plugs warm up.
Soundguy-
I will check the injectors. Sounds like you suspect a small leak which is bleeding off presure/letting in air?

Those Yanmar engines (like in your 855) do start quite well in cold weather...not so the Deere engines in your 4120.
Even if the indicator light doesn't light up, try the glow plugs anyway...easiest thing to do initially and costs nothing but about 20-30 seconds of your time. I suggest you do this before going into the injectors.

 

[jenkinsph]

Those Yanmar engines (like in your 855) do start quite well in cold weather...not so the Deere engines in your 4120.
Even if the indicator light doesn't light up, try the glow plugs anyway...easiest thing to do initially and costs nothing but about 20-30 seconds of your time. I suggest you do this before going into the injectors.

I agree with Roy on this, an easy first thing to try. The Deere engines doesn't start up as easily as the Yanmars.

 

[deere5105]

My 5303 does same when starting. Seems worse in colder weather. I do not have glow plugs, but do have Intake Heater. After trying that out makes a huge difference. My previous 5105 had same motor but was not turbo and did not have this cold start issue.

 

[Soundguy]

yes.. I'm suspecting a small leak / air.

easy enough to test and do the glo as well.

soundguy

 

[dusty3030]

My 2011 4120 does the same.
Not bad unless it has set up for a couple of weeks.

 

[jbarker855]

Well maybe it's just normal for these tractors?
I will still try the glow plugs to see if it helps, but I need to wait a few days. The tractor only runs rough on startup if it has been sitting for several days. Since I used it yesterday, it will start fine today no matter what. I'll let you guys know what I find.
If using the glow plugs does not make a noticeable difference, the next thing I will do is let it sit for a few days again and try priming the fuel system using the plunger on top of the fuel filter housing.
-Jay

 

[SPYDERLK]

do you see any dark dust collecting around any of the injectors or injector lines?

soundguy

Well maybe it's just normal for these tractors?
I will still try the glow plugs to see if it helps, but I need to wait a few days. The tractor only runs rough on startup if it has been sitting for several days. Since I used it yesterday, it will start fine today no matter what. I'll let you guys know what I find.
If using the glow plugs does not make a noticeable difference, the next thing I will do is let it sit for a few days again and try priming the fuel system using the plunger on top of the fuel filter housing.
-Jay

soundguys post fits your symptom best. There is probably some air getting into your lines at some of the injectors making the associated cyls light up last. Does it clear suddenly and become perfect? Can you tell how many cyls are involved?
larry

 

[jbarker855]

It does clear suddenly, and when it clears, it runs perfect. I can't really tell how many cylinders are involved.
I can turn a wrench, but have little experience with diesels, so I really appreciate all the advice that's been offered so far. As mentioned before, I'll keep you fellas posted.

 

[Wayne_H]

So, can I ask, who cares? My 88 Ford starts on a few cylinders when very cold outside, but after a few seconds the rest fire off. I've not lost a wink of sleep over it, and it has done it the past 23 years.... This could be normal?

Wayne

 

[Jay4200]

I agree with Roy on this, an easy first thing to try. The Deere engines doesn't start up as easily as the Yanmars.

I thought Deere engines were Yanmars. Aren't they?

JayC

 

[RoyJackson]

I thought Deere engines were Yanmars. Aren't they?

JayC

Not on the new 4x20 series tractors...Deere built.

The older Deere CUTs, including my 4400, have Yanmar engines. All the smaller Deere tractors (up to the 3720) are Yanmar powered.

 

[the6shooter]

My 2 Massey's did / do the same thing, if not using the glow plugs, diesels do require heat to properly ignite. mine always blow a puff of black smoke and in 3 seconds it's over, and I never put them to work untill the are warmed up. when I used to drive big trucks, they all did the same, and that was with Cat, Cummin's and Detroit diesels. Just my 2 cents.

 

[Soundguy]

for the heck of it, try a double glow.. I do that on my diesel pickups if they have been setting for days and it's cold. double glow really seems to help if it's a cold combustion chamber problem.

if the glow / double glow don't help, I'd look at my previous comment of seeing it it is leaking off on one or more lines.

at moment of startup and rough running you can use a wrench to loosen one line at a time. if one line makes less difference than the others.. or no difference.. that is the jug not popping.

chances are ona 4 cyl that is rought.. it's at least banign on 3. on 2 it would really be laboring and hammering. etc..

do only use a tool.. keep fingers and skin away from pressurized fuel fittings / lines.. diesel ( or hyd oil ) injected under skin equals trip to hospital, long recovery, and lots of soft tissue damage / possible loss of digits or limbs.

thus you use cardboard to 'feel' (looks ) for pressurized line leaks, and use tools on the fittings... not hands for either...

soundguy

 

[jbarker855]

So, can I ask, who cares? My 88 Ford starts on a few cylinders when very cold outside, but after a few seconds the rest fire off. I've not lost a wink of sleep over it, and it has done it the past 23 years.... This could be normal?

Wayne

Maybe its normal. If it is, it won't bother me any. I just am trying to figure out if I do have a problem. If I do, I want to fix it before tractor dies at 5:30 am when I am blowing 2 feet of snow off my driveway before going to work.
I will try troubleshooting tomorrow.
As I have mentioned, I really have doubts that it is simply a cold start problem, Reason being: When I start it tomorrow, it will run like junk for a few seconds before clearing up. I could shut it off after running 10 seconds, and when I start it up 8 hours later, it will start fine. That is not because I "warmed it up" for 10 seconds. I suspect fuel pressure is bleeding off. It may never amount to a real problem, but I want to make sure of that.
Jeez- with me acting like such a wimp about this, you probably think I wax my tractor:laughing::laughing:
Don't worry, I don't!
-Jay

 

[RoyJackson]

Jeez- with me acting like such a wimp about this, you probably think I wax my tractor:laughing::laughing:
Don't worry, I don't!
-Jay

I'm not sure if it's still the case, but a few years back, a lot of TBNers did wax their tractors! I keep mine clean, but can't say I've ever waxed any of them...
Well, let's see how those glow plugs work for you...sounds like you should have an answer on that possibility tomorrow. Hope that's all it is...

 

[Soundguy]

i occasionally wax at least one of mine..