What's Does This Part Do?

[PastureKing]

My '80 JD 950 has a pull/push control on the left side that links to the rocker cover. It appears to open/close something in each of the three cylinders. The farmer I bought the tractor from told me he never figured out what it did. I have gone through the operator's manual front to back and cannot find any reference. It seems to only be on the early production models. I have attached a JD Parts detail that shows the linkage (#24).

The control knob is similar to the old type choke control for carburetor, but of course the 950 has the three cylinder diesel Yanmar engine.

I don't want to ruin the engine by placing this control in the wrong setting. I would appreciate any help.

Thanks

 

[Ductape]

Decompressor for cold starting.

 

[Treemonkey1000]

There is that much pressure in the valve cover?

 

[Ductape]

No, it decompresses the cylinders. When its cold out, pull the decompressor out.Crank the engine, let the decompressor go back in.... engine starts.

 

[Gary Fowler]

That is a Yanmar thing. NO glowplugs. I have that same thing on my Yanmar 4220D and at 35 F the engine is pretty hard to start even using the decompressor. I have seen on this site a suggestion that to help starting in cold weather, "borrow" your wifes hair dryer and blow hot air into the air cleaner inlet and engine will start right up. Guess you just have to remember to park close to a 110Volt outlet. Dont use ether on these engines as you may get some pre-ignition and damage the engine. I have used ether on diesels with no problems but they were designed for ether starting, even had the ether can mounted on the block so it injected into the intake manifold. Better be safe than sorrow, so I will try the hair dryer trick when I need to run in cold weather. Wont be much of that, if it is too cold for my tractor, I will likely just stay inside anyway.

 

[PastureKing]

Thanks to all of you for solving this mystery for me. I assume that in normal weather, I just leave it pushed in.

 

[Ductape]

Yes. It should be spring loaded, so leaving it along will leave you with normal compression. Just for fun, next time you start the tractor, pull it out for a few seconds and you'll see how much faster your started spins the motor over.

 

[jinman]

Better be safe than sorrow, so I will try the hair dryer trick when I need to run in cold weather. Wont be much of that, if it is too cold for my tractor, I will likely just stay inside anyway.

Gary, you'll probably have to do that everytime there's one of those infamous Crosby snowstorms and you have to plow your driveway.