Repair of the two bridges in the water outlet area of the block

[jr2766]

Thanks to everybody for the suggestions. A local welding fellow has used a high Nickel cast iron rod to effect repairs in this area and I have a block which is a candidate for the trial.
I'll report results
Jim Runciman
Perth

[Bruce Nicholls]

The aluminium water manifolds will tend to act as anodes as seen by the eaten away condition of many. Not sure if adding extra anodes, either zinc or aluminium would affect this or add more protection to the block.

[Stuart Giles]

The aluminium water manifolds will tend to act as anodes as seen by the eaten away condition of many. Not sure if adding extra anodes, either zinc or aluminium would affect this or add more protection to the block.

A Zinc sacrificial anode should protect the Aluminium. On professional advice, I fitted Zinc sacrificial anodes to a machined from Ali billet widget that normally lives under water on a mate's boat. The last time the boat came out the water for its dry dock anti fouling ritual, the anodes needed replacing but the Bow Thruster gearbox casing that I had made was still OK.

[Bruce Nicholls]

Interesting Stuart. I use aluminium anodes on our boat and the manufacturer advised me that I could mix zinc and ali anodes as I had some good zincs in stock at the time I switched. It is true though that the anode on the aluminium outboard casing for our tender is zinc, and I had not remembered this.