SEAT REPAIRS THAT DON’T LEAK
When installing valve seats, you sometimes run across porosity that leads into water at the base of the counterbore. I like to pressure test after the counterbores are If you have a seat that you’re trying to seal up, you can make a positive chemical bond barrier by machining the O.D. of the seat for a small groove. This allows the retaining compound or sealer of your choice to have a positive contact all the way around the diameter above the leak. Just coat the seat and make sure that when you drive it in that it is liberally coated around the O.D. As a bonus sealing measure on a seat with porosity in the counterbore, I’ll drill and tap a hole in the back side of the head directly above the compromised area as an access hole. Then, I get in and media blast the area, lay down some fluid weld or epoxy and let it dry. You can air dry, heat gun or oven cure. I plug the hole with a pipe plug. I’ve never had one leak after this repair.machined to be sure, if there is a question.

Ron Flood
Cedar Machine
North Branch, MN
May, 2021