Aluminum & bolting Q

[scot]

I ran across an aluminum tail housing for my 471TI. I'm typically no fan of aluminum anything mixed with salt water, but the 50+lb savings could not be passed up. The Detroit 471TI 325hp marine engine came from Detroit with the aluminum tail housing.. so can't be all too bad.

The question is; The bolting that goes into the housing, I can use stainless. How will this react with the aluminum in the salt environment? It's been my experience that carbon steel tends to use the aluminum as an anode and powders female threads.

I believe the Yanmars are basically aluminum engines (but I know little about them). Any "lessons learned" about bolting on these engines?

Any suggestions on anti-seize? Copper based sounds like a bad idea... what about nickel based? .. Or should I use a Locktite type product on the studs going into the tail housing??

Any metal / corrosion experts out there!!

Thanks Scot

[Kevin]

Tef-gel
http://www.tefgel.com/#

[jspiezio]

Scot- Kevin is spot on with Tef-Gel. I would go one step further, in NAVAIR items and in most other aviation items we insulate dissimilar metals with a good two part epoxy primer. The most common primer used is to the mil-spec MIL-P-23377, it is a yellow or green two part zinc-chromate primer. But I think that any good epoxy primer will work well.

I would brush the primer on the inner diameters of the housing and the face where the bolt will seat, as well as the contact areas of the bolts ( shoulder face and maybe the shank) and let it dry. Then I would install with Tef-Gel or something similar (we are required to use various two part sealers that meet MIL or NAS specs, but that is overkill). I know it sounds like a PIA, but when you go to dis-assemble some day and they come apart nice and easy and the housing looks brand new there you will think back and be glad you did it.

[Rawleigh]

Also bond properly and coat regularly with CorrosionX.