Decompression Level

[Philip1126]

I have a Yanmar 2GM20F diesel motor in my 2002 Hunter. I am trying to perform some routine maintenance. My decompression lever seems to have 3 positions. It move upward to the decompression position, but when I lower it for the drive position, there seem to be 2 distinct positions. Should it be pushed all the way down?

 

[Ross]

I have a Yanmar 2GM20F diesel motor in my 2002 Hunter. I am trying to perform some routine maintenance. My decompression lever seems to have 3 positions. It move upward to the decompression position, but when I lower it for the drive position, there seem to be 2 distinct positions. Should it be pushed all the way down?

What does the manual have to say in this regard. lacking a manual I would say yes.

 

[Philip1126]

I have a number of Yanmar manuals (shop, maintenance, etc) and they make no mention of this. The reason I am asking is that I have very recently notices a banging sound when the engine idles (less noticeable at higher revs). I first noticed it after I change the oil and filter. At that time I flipped up the decompression lever just to see how it worked. I am thinking maybe it wasn't all the way down before and is the cause of the banging sound.

 

[sailaway78]

On a 3GM

On the 3GM Yanmar's there is no center indent. Don't think I have ever heard of anything that is half on/half off. One way holds the valve open, the other way it is disengaged. I am wondering if you just have a sticky spot, or something interfering with the movement. It is possible that where you feel the sticky place, it is touching a lifter and just needs to be pushed on past that spot. IMHO you should have it all the way, whether it is compression or de compression.

 

[Warren Milberg]

Re: On a 3GM

I have the same Yanmar 2GM20F (1986 model). My decompression levers only seem to have two positions: engaged or not engaged.

 

[Philip1126]

I want to thank everyone for their replies. I will have another look at the operation of the lever in the next few days