JD 4120 Smoke at start up!

[KennedyDiesel]

Explanation:

The high rpm start is a result of the cold start advance, caused by the mechanical fuel pump being held to WOT until the rack magnet is no longer capable of holding cold start fueling engaged, due to inertia (typically 1800-2000 rpm).

 

[BGL990]

I believe my JD 990 (Yanmar engine) does the same thing and is the reason I'm very likely to put a pre-oiler system on my tractor. Get the oil pumped everywhere it should be and pressure up before even turning it over. WOT starts don't make me feel too warm and fuzzy ...

 

[trlong]

Mike,

Thanks for the correction. After a re-review of the manual, the indicator lights dimming for the first 1-2 sec.'s is /forums/images/graemlins/confused.gif...I was reading the 4110 start proc., not the 4115. 4110, step "8" says turn key to ON position..."9" says check indicator lamps... and "10" says Allow the "glow plugs" to preheat the engine...~ 3 seconds and listen for a click. Engine is now ready to start." However, the 4115 indicator lights come on dim in the ON position and brighten w/i about 2 sec.'s with an audible click. It's starting procedure does not mention pre-heating anything. So, obviously I don't have a clue what it is doing if there are no glow plugs on the 4115 (HST). I assume heating something (air pre-heater as you say..).

Once I knew some thing. Then I went to college and got edgikated.

Tom

"There's a lot I know. There's a lot more I don't know. Only a fool is afraid to admit that."

 

[KennedyDiesel]

There is a difference in how the Yanmars start vs the Powertech engines. The Yanmars start with full fuel and make a big puff, but are still governed to wherever the throttle is placed which is typically low idle.

The Powertech starts like you have the throttle set to max rpm then a couple of seconds after startup it drifts back down to idle. It sounds as if you started the engine with a load on it initially.

I've parked the loaner 4310 and 4710 tractors in the woods overnight and started w/o any preheat in single digits to teens with no throuttle, no complaining and minimal smoke.

Fuel quality and additive (primarily cetane) has a profound effect on smoke and noise.

 

[Sadler]

The OM for my 4120 says smoke is normal at start up. Also says to push key in for 10 seconds to pre heat in cold weather and continue to hold key in after you start for a few seconds more.

 

[Rob52]

my 4320 does the same! Earlier discussion clarified why? Discussion from about December or Jan.05 about diesel rev up.
Be ready for your fuel gauge reading to start having a mind of its own! Sending unit, I'm told!
Loud hydraulic noise around steering column, also has a fix from dealer!

<font color="green"> </font> 4320ehydro/400x/HD Qt bucket/Rb1184 w hydraulics/LX6 /forums/images/graemlins/grin.gif