How Do I Set My Yanmar Valve Clearance?

There are a lot of ways that you can set your valve clearance. You can buy a service manual and follow the procedures to find top dead center of a certain cylinder and measure the gap of certain valves at that point and then rotate a fixed number of degrees and measure another set of valves. 

Or you can do it the easy way!
This method works on pretty much any engine (all Yanmar engines) and does not require a service manual or special tools. 

• Remove the valve cover
• Locate your rocker arms. You will have two rocker arms per cylinder. 2 cylinder engine = 4 rocker arms, for example.
• On one side of the rocker arm will be your valve and valve spring. You will have one exhaust valve and one intake valve per cylinder. On the other side of the rocker arm you will have your pushrod that pushes on the rocker arm from the camshaft. 
• Rotate your engine using a large socket or screwdriver and watch the rocker arms start to move up and down on the valve side (side with the spring).
• Watch for a rocker arm to raise on the valve side and then it will momentarily pause, and then start to go back down. 
• During the momentary stopped position you are at the maximum gap portion of the stroke and THIS is where you want to measure or set your gap. 
• It does not matter which valve you set first or in what order you test the valve gaps. You are simply setting/testing the gap when the valve is at the fully up (closed)  position. This is the position where the pushrod is not trying to depress the spring on the valve.
  

To Set the gap:
Use a 0.006" feeler gauge (feeler gauge sets are sold at all auto parts stores) and slide the gauge in between the top of the valve stem and the rocker arm. Loosen the locking nut on the adjustment bolt and then loosen or tighten the adjuster bolt on the pushrod side of the rocker arm until there is a slight drag on the feeler gauge as you slide it in and out. If the feeler gauge will not move  then you need to loosen the bolt. If the feeler gauge has no resistance then you need to tighten the bolt. Once you have it set correctly just tighten the locknut and move to a different valve. 

Repeat this procedure in any order you want until you have done this on all of the valves. 

So what do the valves set at? Almost all Yanmar engines set at 0.006" (six thousandths of an inch)  so you will need to use a 0.006" feeler gauge.