CM870 no start

[Rawze]

A cross-head failure like that is nothing to take lightly.

How many miles/hours are on this head?. engine?.

Something caused that valve not to close all the way, binding the cross-head and breaking it.

- Pulling the injector and boroscoping the cylinder, piston, valve seats, valves, etc. properly would be the next step. Also, it should be assumed that the valve stem has gotten stressed and now has a chance of being bent in some way.

Putting the cylinder at TDC with the injector out and removing the valve springs for that valve, checking it for any "bent" condition would be prudent too.

After that, if all checks out well, injector re-installed, all the rocker shafts should be loosened up so that all the intake/exhaust valves will shut. Then the intake manifold and the exhaust manifold plated and pressurized to one at a time to 30 psi shop air, checking the valve train for seepage/pressure losses.

Then,. lastly, ensuring there is no issues with the engine brake rockers or their brake-rocker-pistons, etc. that could have hung up and caused it to keep the valve pressed open when it should not have.

That is what I would do if I owned it any ways.