Question about my L4150 engine idle.

[NJDonzi]

Just wondering if its normal to idle high when you start the tractor when its cold? After about 3-4 minutes it will idle normal.

Thanks!

 

[Max Power]

Just wondering if its normal to idle high when you start the tractor when its cold? After about 3-4 minutes it will idle normal.

Thanks!

idling is never good for an engine. The bearing loads are high at idle because of the slow turning of the crankshaft. I always bump it to 1000 or 1200 if I am going to let it sit for a bit or warm up.

diesels work by the heat of compression. when the piston compresses the cylinder of air it raises the temperature of the air to 1000 degrees or so, then fuel is injected into that hot air and it ignites and burns.

so obviously with a cold engine the cylinder walls are absorbing that heat from compression and therefore lowering the air temperature and potentially causing rough running. hence block heaters glow plugs and migration to Florida.

 

[NJDonzi]

Thanks for the reply. Makes perfect sence. It just does it automatically...like a choke. Wasnt sure if it was normal or not.

 

[kuboman]

Thanks for the reply. Makes perfect sence. It just does it automatically...like a choke. Wasnt sure if it was normal or not.

Unless your tractor which I doubt has an automatic idle you have something else going on. Does not sound normal to me.

 

[KennyV]

I'm with Kuboman... I have not seen anything like that on a tractor...

Are you saying the actual RPM is higher... OR it sounds different for the first few min??

 

[NJDonzi]

Yes, thats whats going on. If you start the tractor it will idle normal. Give it a little gas and it will climb to 1400RPM and stay there for about 2 minutes or so. Then pedddle will come back automatically and idle down. If you just start it without giving it any peddle it will just idle normal. Tractor has only 1248 hours on it.

Then hours later when its still a bit warm it will start normal with normal idle even if you give it peddle.

Over the summer it would start normal when it was warm outside. Just when its below say 50 degrees is when it will idle high 1400RPM's.

Not sure whats going on...all I can say is machine runs perfect other then that.

 

[kuboman]

When you say the peddle comes back, what are you referring to?

 

[Deere Dude]

Just wondering if its normal to idle high when you start the tractor when its cold? After about 3-4 minutes it will idle normal.

Thanks!

Maybe tractors are different. My John Deere 3720 idles faster by itself when its cold when first started and then after a minute it naturally slows down, at 32 deg. When it's cold like 0-10 deg it will start up and run faster for about 3-4 minutes then slow down.
Sounds normal to me.

 

[rbargeron]

If I start my L5450 cold without touching the throttle pedal or lever it idles at low rpm. If I speed it up with either the pedal or lever it then idles higher and doesn't fully return to low idle until later. The idle rpm drops gradually as it warms up. I think my L4150 did the same.

Edit - I didn't look in the wsm last night for the idle controller - but I see MichKubota stayed up later and posted the page below.

 

[MichKubota]

I have an L4150 and it also starts out at a high idle and after a few minutes backs down to around 800rpm. It is very noticeable and quick drop in RPM. I have only had the tractor for as few months and just thought it was normal operation.

 

[MichKubota]

Service manual for L4150 describes a Idle Compensator mechanism which controls idle speed. Looks like the two speed idle operation is normal for this tractor. See attached.

 

[kuboman]

Service manual for L4150 describes a Idle Compensator mechanism which controls idle speed. Looks like the two speed idle operation is normal for this tractor. See attached.

Well thanks for that info. Learn something everyday. Seems like a good idea.:thumbsup:

 

[NJDonzi]

Great info guys. Thanks for all the replys! Also thanks for the service manual page posting.

This site is great...

 

[Bobm]

All of the earlier L-3 series (L3350 / L3750 / L4150) have, for lack of a better term, a cold start, high idle throttle positioner. You've described its functionality perfectly...start in colder conditions, idles high, then automatically drops to normal idle after a few minutes... as mentioned, akin to a gas engine with automatic choke. My 1985 L3350 had this feature, but my 1998 L5450 (both L-3) lacks it.

 

[Willl]

My Deere does the same.

 

[nightowl490]

My L4150 runs faster with faster idle at cold start then backs off. It is normal operation! I believe it's in the WSM but as far as I know this is all good!