bolts for exhaust cover 50HP 2 stroke

[CharlieK1988]

I've had to drill out some of my exhaust cover bolts and re-tap at 8mm. My manual says the bolts are "case hardened aluminum". They act like stainless and are slightly magnetic. Are they hard aluminum, stainless or??? If they are aluminum where can I find some 6mm and 8mm bolts that are hardened?
Thank you for any help you can provide.

[Ken]

Charlie,
I don't know why you couldn't go back with pure stainless on those bolts. And be sure to use a quality thread sealer to prevent galling and seizure. I use Permatex 14A thread sealer with Teflon in many places on my boat and Yamaha outboard.
Good luck [img]smile.gif[/img] ,
Ken K

[CharlieK1988]

Hi Ken,
Thanks for the advice. I was afraid to use stainless screws because a of electrolosis. The old bolts were very corroded and weak. I bought the engine with 6 broken bolts that I had to drill out. I ended up using aluminum bolts I got from a motorcycle speed shop. With some Ultra Black sealer it all went together well and is leak tight.
Thanks again.

[Ken]

Charlie,
Glad you solved your problem - now don't go to replacing all the stainless bolts with aluminum on your outboard, like on the head and lower unit - you need the strength of stainless there - just use a quality thread sealer like I recommended and you won't have any problem with electrolysis and corrosion.
Good luck [img]smile.gif[/img] ,
Ken K

[CharlieK1988]

Thanks Ken,
The aluminum bolts have no strength, and I won't use them anywhere else on the motor. I've thought about changing them out (with stainless) but since there are no leaks they'll do for now.
Regards,
Charlie