Engine shutdown

[choffman41]

Any pros or cons between shutting down the engine using compression release vs. using the throttle lever to cut the fuel?

 

[dieselfuelonly]

I've heard you shouldn't use the compression release to shut off the motor. Use the throttle! In the event of a runaway though (diesel engine starts to burn its own oil) you can use the compression release to shut it off.

 

[mark777]

It was my understanding that using the decompression release to continually shut down a Yanmar diesel will weaken and distort the exhaust valve faces and seats.

I don't know how true that is, and I don't shut down the tractor that way so I can't really say either way...but it did sound logical.

Mark

 

[DavesTractor]

It was my understanding that using the decompression release to continually shut down a Yanmar diesel will weaken and distort the exhaust valve faces and seats.

I don't know how true that is, and I don't shut down the tractor that way so I can't really say either way...but it did sound logical.

Mark

Ditto.

 

[Mickey_Fx]

Agree with others the compression release in not the recommended way to shut the engine down. On newer models you shut the engine off with the "ign" switch just like with a gas engine.

 

[dieselfuelonly]

If you turn the ignition off with the engine still running on some of the older tractors like mine, do you risk damaging the charging system? My dad had a sailboat that if you turned the battery bank switch off while the engine was off you could kiss your alternator goodbye!

Sorry to get off topic, just curious!

 

[arthr31]

Ditto on the "no" on using compression release to stop the engine.

As far as turning the key to off while running, I've read that this is acceptable- I read this in hardprinted literature and will take some time over the next day to look it up for you.

The key isn't for ignition since it's diesel, but to run the starter. So, I think it's out of the loop after running <but again, i'm not sure> I'll let you know if I find what I'm recalling. You could also test with a voltmeter and see if something strange happens at the alt after removing the key...

 

[California]

Cites from the YM240 Operation Manual: (same engine as YM2000)

"IMPORTANT Always leave key turned on, in position 'ON', while engine running."

and

"IMPORTANT Do not use decompression lever to stop engine."

 

[tallyho8]

Cites from the YM240 Operation Manual: (same engine as YM2000)"IMPORTANT Always leave key turned on, in position 'ON', while engine running."

Don't you hate it when instructions tell you NOT to do something but don't tell you why? You have to wonder why! Is it because it will damage my alternator? Is it because my gauges don't work while the key is off? Is it because the key may fall out of the ignition switch and get lost?

I frequently turn my key off and remove my keys while the tractor is running to give someone the keys to unlock a gate, move my truck, etc., so far, with no bad results.

 

[Tom_Veatch]

Cites from the YM240 Operation Manual: (same engine as YM2000)

"IMPORTANT Always leave key turned on, in position 'ON', while engine running."
...

The Electrical Schematic for my YM2220 shows a power feed back to the regulator from the same line that provides power to the temp and fuel gauges. Possibly a voltage sensing feed for regulating alternator output??

Lacking an internal schematic of the regulator (and more importantly, lacking the knowledge to read that schematic even if I had one) I don't know what happens if that voltage goes to zero while the alternator is running - unregulated output from the alternator???

I do know that I've frequently turned off the master switch with the engine running. I also know that I've replaced two regulators. Is there a connection between those two events? Not necessarily, but certainly possible. I think I'll be a little more concientious in the future about not turning off the master switch with the engine running.

Thanks, California.

 

[chriswheeler]

My YM 3000 and JD 950 O&M manuals says the same thing. We had a mid size Cat V12 generator that had compression release valves on both banks of the engine. 50's vintage, about 900 hp. Instruction manual stated that this was to be used in case of emergancy shut down and not under normal conditions. Normal shutdown was the same as most, by closeing the rack to the fuel pump. I suspect that most are the same, shutting off the the fuel rack. Decompression works well for starting these small engines on a cold morning, building up oil pressure first before starting. Would never use to shut down unless it ran away and their was no other way to shut it down.
Chris

 

[svcguy]

We are actually talking about two different systems, key vs pump. When a diesel is shut down, you simply cut off the fuel supply or the air supply. Either one will kill the engine. On most tractors, especially older units, this is done with the throttle lever. You run the throttle down to idle, then past that point with the throttle lever, which cuts the fuel delivery at the fuel injection pump and that stops the engine. This type of tractor is the type where it is recommended not to turn your ignition off until after the engine stops (ignition switch is for the charging system). Other tractors use a 12 volt actuator or solenoid to cut air off at the intake manifold. This is the type that when you turn the key on, it opens the air intake and with the key off, it shuts the engine down by shutting off the air supply. Both work well, but the first type is where you don't want to turn the key off until the engine has stopped.

 

[xlr82v2]

Which tractors choke off the intake to kill the engine? I've never seen one like this...

All the tractors and any other diesels that had key operated kill systems had a solenoid on the injector pump that electromechanically moved the rack to cutoff instead of doing it manually via a knob and cable or with the throttle.

 

[svcguy]

An example of a solenoid air shut down is used by Iseki. The TU series use the 'choke' type shutdown. You are absolutely correct though, many use the same system on a pump, either air or fuel.

 

[choffman41]

Remember the old GMC 71 series diesels, regular shutdown was by shutting off fuel, but there was also an air block for emergency shutdown for runaways.