Is a Third Wrench Needed When Adjusting the Valves on an Old Diesel?

This is how Kent deals with the problem

You may have seen or heard that you need a "third" wrench when adjusting the valves on an older OM615 OM616 or OM617 diesel engine. A third wrench was originally produced to hold the hex cap at the top end of the valve to keep the valve from turning when attempted to adjust the two nuts above it. In all the valves Kent has adjusted over the years less than 10 percent of these required holding in place when adjusting in the nuts. In most cases the two special bent wrenches are enough to complete the adjustment.

Problem & Solution

Common among these chassis:

W110 W111 W112 Sedan

On those stubborn valves that want to turn during adjustment Kent found it was very cumbersome to use that big "third" wrench. Rather, he found that you could take a flat bar, pry bar, or VERY big flat blade screw driver and "jam it" up against the hex cap to keep the valve from spinning. This technique even works faster if you have a helper hold the bar while you complete adjusting the two nuts (see image above.)

This is the reason Kent does not sell a third wrench with his valve adjusting wrench kit. For a bettery explaination of how his wrenches work watch this youtube video: