My Clutch Is Stuck
Difficulty - EASY
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It has happened to almost every Yanmar owner- Start up your tractor, try to put in into gear, and all you get is a terrible grinding noise. Or, if you are in the habit of starting your tractor in gear, you will not be so proud that your little Yanmar starts up so quickly- as you are shooting through your closed garage door because your clutch did not release. It is so common, in fact, that you will notice a special latch on most Yanmar tractor models that you use to hold the clutch pedal down while the tractor is in storage.
So what is happening? The Yanmar clutch disc is lined with a fibrous material. The flywheel is a metal disc. They are both sandwiched together at great pressure (that is what transfers all of that diesel torque to the wheels after all) by the pressure plate- all inside of your bell housing. The bell housing is often subject to condensation buildup, rice field water, rain water, etc and is frequently a very humid place. These factors cause the disc and flywheel to stick together. It is not like a welded together type of stuck, more like when the pages of a book get stuck together when they have been wet. When you press in on the clutch, the pressure plate releases the pressure on the clutch disc but it does not force the disc back. The disc is just stuck and needs a little encouragement to release.
What to do? If you have a mower hooked up to your PTO you can put the PTO in gear, hold the clutch pedal down, and rev the engine quickly up and then quickly down. This rapid change in torque will usually break the clutch free. Sometimes you can even just apply the brakes when driving the tractor with the clutch down. You are just looking for the torque of the engine to separate the disc from the flywheel. It is rarely ever stuck so bad that the tractor will need to be split.
This is a dangerous procedure since your clutch is not going to stop the tractor or the PTO- and you have to start the tractor in gear since you will not be able to shift it once it is started. If you do not feel like you can do the above procedures safely or have any questions- contact your Yanmar dealer or mechanic to help.