Working on 86 Force 85 outboard.
Head bolts all grade 8 (5 marks)
Original exhaust bolts grade 5 (3 marks)
Some of the exhaust bolts have been relaced with a bolt marked "SS 30400"
My question is: Are the bolts marked "SS 30400" as strong as the original grade 5 bolts?
If that means 304 stainless steel then no. Randy Replogle
Jim, My experience is yes, 304 or 818 (more common name), are superior to grade 5 in strength, but not cycles. In your application, you will not experience a failure, but you must use antiseize. Steve
Jim:
An excerpt from the below site may be informative.
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OK.....well, it was more of a personal interest...I decided to replace with what was original.
Steve's answer was interesting...about the cycles....the head gasket in this engine blew, and water was coming out around the head, as well as the exhaust manifold bolts......I wonder (I didn't think to check before I disassembled) if the major exhaust water leaks were around the stainless bolts.
I guess it does not matter, as NONE of the bolts were torqued to spec.....though, the manual says to check them every so often (10 hours?,
100 hours?)....This motor is new to me, 2-3 hours on it, and 18 months out of a rebuild for the previous owners. I doubt the previous owners where very "maintenance" savvy.Thanks everyone.
It should be fine for the exhaust. It will not loose strength as much as a grade 5 under heat cycling, because it is not/can not be heat treated. It will also not corrode away like the steel bold will.
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