Yanmar Clutch Will Not Release

This is actually a very common problem with Yanmar tractors for some reason. In fact, it is so common that Yanmar added a clutch lock to many/most of their tractor models. The lock is designed to hold the clutch pedal down if you are not going to be using the tractor for a while. If you don't have the lock anymore you can also use something like a 2x4 cut to proper length to wedge against the pedal and seat. 

The problem is that the clutch disc adheres to the flywheel after sitting for a period of time. Depending on the conditions when parked, this can be as short as just a day or two.  When you depress the clutch pedal, you are just releasing the spring force of the pressure plate that is smashing the clutch disc against the flywheel. If the clutch disc gets stuck to the pressure plate then there is nothing in that mechanism that will try to pull them back apart.

I have found that the best way to unstick a Yanmar clutch is to hook up to a brush mower if you have one. CAREFULLY start the tractor with the PTO in 1st gear and the transmission in neutral. Hold the clutch pedal down fully and repeatedly rev the engine up and down quickly to try to shock the clutch loose from the pressure plate.  This breaks the clutch free in most cases. Be very careful!

Alternately, you can hook up to something like a disc or plow and pull it with the clutch pedal held down. It will eventually break free. Do not ever pull from a point above the rear axle centerline or you could cause the tractor to flip over backwards! Always pull from the factory drawbar position. 

If you continue to have trouble getting the clutch to break free you might end up having to split the tractor and manually pry the clutch apart from the flywheel but, in 20 years of working on Yanmars, I have never had to do this. 

So why is this only common in Yanmar tractors? I have never really heard a good explanation but some people have suggested that the clutch friction material that Yanmar uses might just be more prone to sticking to the flywheel than other brands.