What is the correct use of the decompression/compression release knob?

[clemsonfor]

A compression release is a great fall back in the event of a run away condition.

As small as these tractors are you can jump off one or open hood and stuff your shirt in the intake....but those are crazy times and I also would not want to be around one running away any longer than needed. I might throw the lever too!

 

[California]

An additional use that nobody's mentioned: These tall narrow tractors were designed for tilling rice paddies. I wonder how many times one has gone into a hole, flopped over on its side, then later was cranked with compression released to get water out of the cylinders.



Photo I found on Yanmar-Japan's website.

 

[normde2001]

I know, many old big generators used to have a hand pump, for prelube. You never see that anymore. Everything is just so disposible, and that's the way the manufacturers like it.

Right, disposable like our 40-45 year-old Yanmars and the 50s vintage Ford n models.

 

[Jtullis13]

Does the average oil pump even move any oil at cranking speed?

I made a prelube system for one of my generators, without success. I found it had to be quite a pump.

Well on my 2 Yanmars it makes a difference. I have installed an oil PSI gauge, and when cranking with the decompression lever pulled I can hear the oil start to be picked up by the pump and my gauge will start to climb, so I know its circulating the oil and building a little pressure prior to starting.

 

[winston1]

The oil light on my old 2002D would go out in less than 2 seconds of cranking.

 

[Industrial Toys]

Cranking and not starting? That is interesting.

 

[winston1]

Cranking and not starting? That is interesting.

Will not start without releasing compression release. Was trying to illustrate oil pressure established by turning engine over with compression release before engine start.

 

[Jtullis13]

Thanks Winston, that is what I was trying to explain in my reply post about Industrial Toys question about the oil pump.