Oil & Fuel RPMs at Diesel Start-up

[cp1969]

</font><font color="blue" class="small">(

It must be when the glow plugs are turned on that some amount of fuel is allowed into the combustion chamber or something to allow the engine RPM to be higher than the throttle setting.

Randy )</font>

Not on an L3000. Electricity has nothing to do with it; it has a purely mechanical injection pump. It's nothing but the governor doing its job.

 

[73jeep]

Thanks for all the responses!
It appears that the majority of you guys are doing the initial start-up at idle/low rpms which is probably what I'll do.
Manual states to heat glow plugs for 5-7 seconds, and as for variant temperature warm up times:
.......32 degrees F and up ------ 5-10 minutes.
......15-32 degrees ------------- 10-20 minutes.
....... -5-15 degrees -------------20-30 minutes.
...... less than minus 5 degrees --30 or more minutes.
Here in my part of N.C., 5-10 minute warmup is all I'll ever need to worry about.

 

[JimR]

I use 1200-1400 for startups and let her run there for a few mintues.

 

[RalphVa]

Don't know why people keep mentioning about it being bad to let diesels idle for long periods. In Vermont, bus drivers would leave their buses running all night long when it got down to about -20 F at night.

Of course, in the far north, they shut them down but have to have them plugged in to keep the engines warm in places where it can get to -40 and below. It's that or leave them idling.

Ralph

 

[JerryG]

I have a 100 kW, 166 HP Perkins generator. When the automatic transfer switch transfers to generator power, the engine starts and goes straight to full speed. When the transfer switch returns to the Power Company, the engine just shuts off. I don’t know how smaller units work.

 

[Soundguy]

That's about the only way to run a demand system... you gotta have the power -now- and you may be starting under load... Now.. presumably, that generator is not meant but for intermittant use.. whereas a tractor is made for frequent use. My guess is if you started a tractor like that all the time, full throttle, with all hyds and pto load to click in at the moment of starting, I'd guess the engine would not last as long, vs the genny hat might have to do that? a couple times a month? max? It's a trade off.. instant power at the cost of some minscule percentage of engine life..

Soundguy

 

[Soundguy]

I've herd of some units that deliver max fuel at the injector pump reguardless of the throttle setting, based on the gov and fuel injector pump design.. after starting, then throttle setting is referenced.. etc. Also.. some pumps have an excess fuel knob to help with starting in extreme cold..

Soundguy

</font><font color="blue" class="small">( It must be when the glow plugs are turned on that some amount of fuel is allowed into the combustion chamber or something to allow the engine RPM to be higher than the throttle setting.

Randy )

Not on an L3000. Electricity has nothing to do with it; it has a purely mechanical injection pump. It's nothing but the governor doing its job.
)</font>

 

[3RRL]

You must be right Soundguy, at least about my Kama. I usually start it with a smidgen of throttle trying to catch around 800rpms at start up. But the engine always roars to life before settling down, even when I forget to set the throttle for start up.

 

[cp1969]

All governed mechanical injection pumps start with the rack (the thing that controls how much fuel is injected) in the full power position. It gets into that position when you shut the engine off. When you shut down, fuel is cut off and the engine starts slowing down. The governor doesn't know why the engine is slowing down, so it opens the rack to speed it back up. But since there is no fuel available, engine rpm continues to drop. The more engine rpm drops, the more the governor opens the rack until it is wide open. Thus the next time you start, you hear this little surge as the engine starts at full power and overshoots the rpm setting of the throttle, then settles down to the rpm commanded by the governor.

The throttle lever is not connected to the rack. It is connected to the governor. It tells the governor what rpm you want; the governor gives the engine enough fuel (via the rack) to maintain that rpm.

 

[5030]

Flusher:

(Interesting forum name)

If you tractor wet stacks then you have an internal problem. Diesels with good comnpression and no ring problems won't wet stack unless they are idled for hours on end at very low ambient temperatures.