material question….

[amuller]

Finally putting my ’72 V4 back on the boat.

The bolts than came off appear to be stainless (2 marks on the heads at 90 deg) and the nuts are aluminum, as are some large sturdy washers. Is this the original OMC material choice? I seem to vaguely remember finding nuts, bolts, and washers all in aluminum in this application a long time ago.

Of course I don’t know the alloys involved, but there could be a concern about stress corrosion cracking of stainless fasteners in salt water service if not chosen correctly.

[ryanjames170]

it was probaly because they could not use SS nuts.. if you crank down to much on SS nuts on SS bolts you will never get them apart.. so my guess is aluminum was the next choice better then just plain steel.

[garry-in-michigan]

The 75 Horse V-4 came with Aluminum nuts, bolts and washers to eliminate any salt water corrosion. I used some at home to hang a shelf above the washing machine for soap and stuff. As far as I know, they still have not corroded. . . 😀

[frankr]

True, the early ones had aluminum bolts, later they came with stainless ones. I still have some in my goody box.

[amuller]

Either SS on SS or Al on Al is subject to galling. Somewhere else I was reading that Mercury uses copper alloy nuts on fine thread SS bolts.

So did they originally use lock nuts, or double nuts, or lock washers, or….?

[frankr]

Nope, just 1/2-13 bolts and nuts, with those big washers.

[amuller]

So what does experience suggest as the best choices in hardware for motors big enough to need bolting on?

[Mumbles]

Personally, I use stainless as we are surrounded by salt water and then I’ll never have to worry about them corroding away. Everything gets a good coating of Sikaflex to keep water out of the transom and prevent the threads from galling when snugging up the nuts. Galvanised hardware would probably be OK for occasional dips in the lake.

[Anonymous]

I seem to remember from my working days that when we used SS nuts on SS bolts we used a anti seize compound.
Kirk

[frankr]

quote amuller:

So what does experience suggest as the best choices in hardware for motors big enough to need bolting on?

Stainless Steel.

[Author]

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