Mercruiser 170 alternator question

[T-Max]

I've seen frequent mention about the alternator swap / kit issue with these engines. I'm currently involved in more pressing issues, but once I get this thing going I might want to address this alternator thing. My simple question is this: Why can't I just replace the current charging system with an automotive system from the junkyard; that is, an alternator that physically fits onto the motor (with the relevant adaptation, of course), and then either the stock water-cooled regulator or a regulator set-up from the junkyard car?

As to that water cooled regulator, what's up with that? Why does it have to be water cooled?

Maybe I'm getting wise now that I'm asking these questions. Is the problem with my proposed swap and the answer to my last question simply that the stock charging system is high output -- higher than an automotive alternator might be able to handle?

I'm a newbie to boats but have extensive automotive experience. I can't figure why the boat's electrical needs would be that much more than a car's, but if that's the case I guess you guys will tell me.

And if that is the case, wouldn't an extra battery in the system tend to solve that problem?

I'm hoping my stock system is working fine, but I'm trying to get a jump on the problem in the event I need to address it once I get this boat going.

 

[TiredoleBoy]

Re: Mercruiser 170 alternator question

I've seen frequent mention about the alternator swap / kit issue with these engines. I'm currently involved in more pressing issues, but once I get this thing going I might want to address this alternator thing. My simple question is this: Why can't I just replace the current charging system with an automotive system from the junkyard; that is, an alternator that physically fits onto the motor (with the relevant adaptation, of course), and then either the stock water-cooled regulator or a regulator set-up from the junkyard car?The car alternator does not have a flame arrestor installed on it. This would be a dangerous situation. Also the regulator is not mad for continuous moisture being around it. The contacts would contstantly require cleaning.

As to that water cooled regulator, what's up with that? Why does it have to be water cooled? Mine blew out 3 years after I bought the boat. I refitted the system completely and did away with the stock water cooled system.

Maybe I'm getting wise now that I'm asking these questions. Is the problem with my proposed swap and the answer to my last question simply that the stock charging system is high output -- higher than an automotive alternator might be able to handle?

I'm a newbie to boats but have extensive automotive experience. I can't figure why the boat's electrical needs would be that much more than a car's, but if that's the case I guess you guys will tell me.
Again the boat is in water, the car is not.
And if that is the case, wouldn't an extra battery in the system tend to solve that problem?

I'm hoping my stock system is working fine, but I'm trying to get a jump on the problem in the event I need to address it once I get this boat going.

Read in red

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 170 alternator question

You can use a Delco 10si alternator but it needs to be "Marine" which are altered to prevent sparks from excaping the housing using spark screens on all the openings in it. All components that have that are related to fuel or spark producing must be USCG approved (marine): starter, distributor, alternator, fuel pump, carburator.

You can fab your own alternator brackets, measure for the belt and buy a marine alt:
http://www.dbelectrical.com/p-3610-...r-mercruiser-3-wire-105-amp-10si-adr0106.aspx

or get the whole kit brackets, belt, alternator and necessary wiring for the conversion for it:
breezeworks.com