Decompression doing anything?

[Todd8665]

I've had my YM2210D for about two months now. I religiously pull the decompression lever each time I start the tractor, then push it back in once started. My problem is that I can't sense any difference in the engine (sound, idle, smoke color) when the lever is pulled vs. the lever being pushed in. I can open the hood and pull the decompression lever and see the linkage work all the way to the valve cover and everything there seems normal.

Question for anyone with a 2210 or similar 2 cylinder Yanmar. Can you tell when the decompression lever is pulled by the way your engine is running?? I there some other way for me to tell whether or not the decompression level is actually working - eg relieving the pressure. I suppose I could try and find some way to hand crank the engine, but im not sure if that would tell me much.

Thanks

 

[deepNdirt]

Welcome to TBN,

Does the engine actually startup while the decompression lever is open? Mine will not start, after it has turned over for about 5-10 seconds and when I release the lever it does puff some smoke and starts right up,
If yours starts when the lever is applied, then I'd say the decompression valve is remaining closed,
You should be noticing a big difference in the engine speed while turning over when open verses when closed,

 

[winston1]

The compression release holds the exhaust valves from completely closing, therefore no compression. There should be a very noticeable difference in ease and speed of engine turn over when pulled. Your engine should not crank or run when the release is pulled. There is a cam action on ref #39 on this drawing. Yanmar Tractor Parts: HEAD

 

[Todd8665]

Thanks for the reply deepiNdirt and Winston.

Sounds like my decompression is not working because my engine definitely runs with the lever pulled. From Winston's diagram I see a few pins/small bolts along that shaft. I'd imagine that if I lost one or more of them then that would negate any Cam action....

Sigh,,,I really don't want to pull the valve cover, but I have been wondering about my valve clearance too. My valve cover is similar to the diagram in that it also has the small inspection plates? (#44 on diagram). I pull them off and peek inside to see if I can see anything.

 

[clemsonfor]

the lever turns not pulls. i just dont think your linkages are connected. not nessisarily under the valve cover.

It should sound like wooomp wooomp wooomp when it has compression and like wa wa wa wa wa wa wa, when its open. Its a noticeable difference in cranking speed even with a fully charged battery.

Plus like they said its impossible to start it with the lever engaged, as there is no compression

 

[Todd8665]

clemsonfor,

Correct...on my tractor you pull the "knob/cable" which turns the lever at the valve cover. I can see/watch all this take place with the hood open - and/or I can move the lever at the valve cover by hand. Same results...

 

[Scotty Dive]

Just my 2 cents here. On my 2020D - 3cyl, I don't notice a great deal of difference with the decompression lever pulled when the outside temperatures are 60 or better. Mine will actually begin to start while its pulled. I do know that mine is working because once I pulled it while it was running and it eventually dies. Now in the winter when everything is cold and that oil doesn't want to flow - I can really notice the difference.

 

[normde2001]

Just my 2 cents here. On my 2020D - 3cyl, I don't notice a great deal of difference with the decompression lever pulled when the outside temperatures are 60 or better. Mine will actually begin to start while its pulled. I do know that mine is working because once I pulled it while it was running and it eventually dies. Now in the winter when everything is cold and that oil doesn't want to flow - I can really notice the difference.

It needs adjustment. Should not attempt to start, and should immediately lose compression when activated, ( although you should not activate when running).

 

[kenmac]

My 3110 will not start with decomp pulled

 

[Scotty Dive]

Same here. Mine won't start either but it wants to and as soon as I close the decomp it fires up - not as much in very cold weather though

 

[careyo63]

In Winstons Pic. make sure the Pin I believe #49 is there and isn't broken. It goes through the Arm#41 and the Shaft#39. It's small and watch that the shaft is actually turning. That would be a good reason.

 

[Todd8665]

Well normde your the overall winner... I pulled the small plate on the top of the valve cover off, and within four seconds thought - huh the linkage just needs adjusting. Wouldn't really have known without being able to see inside and could tell that the cable/wire of the pull cord/decompression lever(one at the dashboard) didn't pull the lever far enough to press on the valve springs - thus limiting compression. I would bet that I was losing some compression, but not enough to notice. I'll pull some slack out of the pull cord and tighten it back up. - see what happens. One can/could also adjust the amount this lever pushes down through these holes - their purpose i suppose - via a nut and bolt on the rod, under the cover.

This all begs the question. Some people responding to this post said that no way would their tractor start or run with the decompression level pulled. Other said theirs would. Right now mine starts and runs with only slight functionality of the decompression lever. I see now, and I bet I could, max it out and not be able to start/run the tractor with it pulled. Which is right?? I think I will...keep my foot out my mouth and see if anyone chimes in. Meanwhile I'll consult the manual. **edit - I just re-read the posts and it seems that i am the only one who can start thrir tractor with the lever pulled. Looks like I'll make it so that it pulls "completely"***

Of course in my world this 3 minute job is going to take much longer since the bolt that holds/puts pressure on the wire has had its head twisted off at some point in the past, and the metal of the bolt is about the hardness of molding clay...there's gotta be a bolt of the same thread in a drawer in the garage somewhere...

 

[kenmac]

I was kinda of thinking you weren't pulling the cable far enough out. At first, I thought I was pulling my decomp lever, but the tractor started. I found I wasn't pulling it hard enough (I stopped pulling when the cable met resistance) to activate the system

 

[deepNdirt]

Here In Ga, our climate/weather never gets cold enough to need to use the Decompression,(well until lately )
Though It does come in handy when the battery goes weak, instead of wearing the battery on down I can use the compression lever spinning the engine over faster and when letting go it fires right up,:thumbsup:

 

[careyo63]

The 2500 has a cable I didn't seem to care for it just for this reason. With the Linkage on the 2000 turn it until it stops and then about another 1/4 turn and you know and can feel the Valves open. I always use my Decompression lever on a Cold/First start. When the Oil light goes out let it go and time to do some work!
I just finished my First of the Yr. Maint. and was Shocked again on how good my Oil Pressure comes up. It's sat for a couple of Months so I know everythings in the pan. New Filter with No Oil in it 6 Qts 15-40 from Wally World. In 10 Sec. The Light was out and back to the normal 5-6sec. on cold starts. It's never been Refurbished and all Org.:thumbsup:

 

[bmaverick]

So, you pull the decompression lever out leaving it there and then turn the key to start? How weird is that? I had read that you first pull the decompression lever out, wait a moment and then push it back in before starting. Thus, the engine is decompressed and reset before the starter is engaged making for easy starting.

 

[clemsonfor]

NO you throw the lever or pull it how ever your set up and hold it open and crank, once oil is up to pressure or engine is up to speed you close it to give the engine back compression.

What good is looseing the compression before you start it then putting the compression back before you start it also?

 

[buickanddeere]

Somebody here is badly missing the point of decompression .
If you read the manual I assume it reads something like starting a two cylinder Deere diesel.
With fuel shut off, engine decompressed rotate until oil pressure registers. Continue cranking and apply compression. After a rotation on compression add fuel.
Cranking with the fuel on and decompressed is ridiculous as it wets the combustion chamber head, piston and cylinder walls with raw fuel. Next the crankcase oil becomes diluted with diesel.
The wetted combustion chamber also causes "startup knocking".

 

[Smoody]

You said you pull for decompression?

On the 3 2210's I have owned, the decompression was under the dash on the left side and you turned it, not pull.

It reads to me you have a pull style decomp on the dash? please take a pic, just curious.

 

[Todd8665]

You said you pull for decompression?

On the 3 2210's I have owned, the decompression was under the dash on the left side and you turned it, not pull.

It reads to me you have a pull style decomp on the dash? please take a pic, just curious.

I can take a pic, but yes the decomp is like the "choke" pull cord that you would find on any lawn tractor. It has a rigid wire instead of a cable though.