Pin hole in cast iron head
The hole turned out to be of my own making and not a casting defect. With a little probing I was able to open the hole up to 3/16 quite easily. I had hoped to try some MIG patching or even brazing but the metal is just too thin. In the end it was drilled out to 5/16" for the attempted repair.
I realize this could be a spectacular failure but it is something I am willing to try. If I don't try the repair on this motor (smog 360), when will I ever attempt it again?
With the hole so large and the metal so thin I did not think a port side (low pressure side) epoxy patch had much of a chance of success on its own. I wanted some solution that formed a plug on the high pressure (water) side. See the pictures for what I ended up trying. It is basically a jack nut anchor for blind holes + Belzona epoxy. The jack nut spreads out on the back (water) side of the hole and pulls the washer head tight against the intake port side of the hole. The jack nut and flat head screw are sealing the hole and taking the force of the water pressure. The epoxy is acting as a gasket. That's the hope anyway.
Picture 1 is the back side of a jack nut installed in a test piece of scrap aluminum.
Picture 2 is the back side of a second jack nut test piece but this time filled with epoxy before insertion and expansion.
Picture 3 is a dry run of the jack nut and screw inserted in the hole in the port.
Picture 4 shows the jack nut after sand blasting and the hole in the port.
Picture 5 shows the Belzona, the jack nut and screw and some fiberglass reinforcing mesh.
Picture 6 shows the completed repair after a light sanding with a cartridge roll.
Flow testing after the repair showed no change in flow up to and including 0.400 lift, then about a 3-5 cfm change at high lifts. Total thickness of the high spot of the repair is about 0.100" or a little more.
I just hope there is enough wall thickness in the repair area (and in the other 7 ports) to stand up to the water pressure.
The hole turned out to be of my own making and not a casting defect. With a little probing I was able to open the hole up to 3/16 quite easily. I had hoped to try some MIG patching or even brazing but the metal is just too thin. In the end it was drilled out to 5/16" for the attempted repair.
I realize this could be a spectacular failure but it is something I am willing to try. If I don't try the repair on this motor (smog 360), when will I ever attempt it again?
With the hole so large and the metal so thin I did not think a port side (low pressure side) epoxy patch had much of a chance of success on its own. I wanted some solution that formed a plug on the high pressure (water) side. See the pictures for what I ended up trying. It is basically a jack nut anchor for blind holes + Belzona epoxy. The jack nut spreads out on the back (water) side of the hole and pulls the washer head tight against the intake port side of the hole. The jack nut and flat head screw are sealing the hole and taking the force of the water pressure. The epoxy is acting as a gasket. That's the hope anyway.
Picture 1 is the back side of a jack nut installed in a test piece of scrap aluminum.
Picture 2 is the back side of a second jack nut test piece but this time filled with epoxy before insertion and expansion.
Picture 3 is a dry run of the jack nut and screw inserted in the hole in the port.
Picture 4 shows the jack nut after sand blasting and the hole in the port.
Picture 5 shows the Belzona, the jack nut and screw and some fiberglass reinforcing mesh.
Picture 6 shows the completed repair after a light sanding with a cartridge roll.
Flow testing after the repair showed no change in flow up to and including 0.400 lift, then about a 3-5 cfm change at high lifts. Total thickness of the high spot of the repair is about 0.100" or a little more.
I just hope there is enough wall thickness in the repair area (and in the other 7 ports) to stand up to the water pressure.