Air box check valve cleaning

What would be the proper way to clean these check valves. Or should I buy new. 4 new ones cost $200

Please explain what these valves do and where located. I feel sure some forum members will be able to help out if they know what the question relates to.

Airboxes? Checkvalves? Do you have a D.D. engine.
If they are what I think you are referring to they are oil drains back to the sump and should open upon engine shutdown.

Often they can be cleaned with diesel or some other solvent. It is usually goo from old oil and some dirt that sticks them up.

If they still won't work then you may need to replace them.

And no , I'm not a D.D. guy, just have run across mention of this problem often enough that I remembered.

Also tell what the engine is, don't make us guess.

Yes, I guess I was a little vague. They are DD 6v92's. airbox checkvalve s. I tried cleaning them in a parts cleaner and none of them would close properly. I understand why this is a maintenance item that often goes "overlooked". Someone has rerouted them to "crap boxes". Which I believe is best. Replaced them with new.