Use of compression release

[reb]

I realize the compression release is to be used only as a starting aid. My neighbor recently bought a well-used gray market tractor from some folks that told him that pulling the compression release is the way to turn the engine off. He has put maybe 10-20 hours on the meter and now it won't start. It looks to me that it has no compression. When the starter is engaged the engine speed is about the same with the compression release on or off. Is it likely that the misuse of the release is related to his problem? How does that affect the engine?

[clemsonfor]

The compression release holds the exhaust valves i beleive open (pretty sure its exhaust and not intake) to release compression.

Its not suppose to be used to kill engine but some will use it like that. I would only use it in emergency like stuck injection pump or something on a runaway engine.

It could be that the lever is stuck or hung open where it comes through the vavle cover gasket so there is no compression. Raise the hood and look at where it connects to make sure its functioning.

[winston1]

If it acts like no compression that is where I would begin looking making sure the shaft is free and turning where it goes through the valve cover.

[California]

bought a well-used gray market tractor from some folks that told him that pulling the compression release is the way to turn the engine off.

I was told the same thing when I bought my Yanmars. Before I could make the YM186D shut down as intended (by pulling the throttle to zero) I had to adjust its throttle linkage and then added a non-stock additional return spring. So apparently the compression release method had been used for a long time. Years of using the compression release to stop them doesn't seem to have hurt them.

However the manual says to not do this.

In your instance: I don't think you have any lasting damage but as Clemson and Winston said, something in the compresion release linkage must be out of adjustment and holding the valves open. The tractor should be fine after you get that adjusted properly.

[clemsonfor]

I have heard some say not to cut the motor off with the comp. release lever casue the pistons could hit the valves. Well if the valves are going to hit when you open the comp release to shut it down, then they would hit when you were cranking it also???

I still push my throttle foward all the way but have made a habit of pulling the linkage shut all the way to make sure it shuts down quickly and does not deisel as it sometimes does not cut off as soon as you close the hand throttle.

[Coldwater]

compression release is a big help with low batteries.if you sell tractors and start them a lot but don't run them long is a big help. i wish all diesel had them

[reb]

Thanx for the replies.

The linkage is ok. I think the engine is just worn out. He commented about lack of power shortly before it quit on him.

I can't visualize any way that using the compression release to turn off the engine can hurt. Just asking if anyone knew more about it than I.

[V1Rotate]

When you shut down the engine with the compression release the fuel injector pump is is still pumping, that will put raw fuel into the cylinders that won't be burnt. That fuel could possibly wash the oil off of the clyinder walls, leading to increased wear.

[winston1]

When you shut down the engine with the compression release the fuel injector pump is is still pumping, that will put raw fuel into the cylinders that won't be burnt. That fuel could possibly wash the oil off of the clyinder walls, leading to increased wear.

That makes sense. First explantion I have heard.