Mercruiser 3.7L 1986 charging problem

I have a Mercruiser 3.7L 1986 224C.I.D engine with power steering in my boat and I think the problem I have is with the stator and rotor. I bought the boat a week ago and it was charging fine but then I took it out this weekend and noticed when we were riding that the voltage was at about 11. We stopped to fish and when we tried to start the battery was dead. I happened to have an extra battery and got it going so I thought maybe it was the battery. We drove for about 15 minutes and still the voltage was at about 11 then it dropped to nothing and about a minute later the engine stalled out. We spent 3 hours waiting for a tow back to where we had our car and trailer. I charged both of my batteries back up but when I put one of the batteries back in the boat and connected the cables it sparked a lot and seems there is a load on it even with everything turned off. Could the load be coming from the stator, rotor, and or voltage regulator? Will disconnecting the old system and using your alternator conversion kit solve this problem?

Re: Mercruiser 3.7L 1986 charging problem

One thing that was very common on the 470 engines was the magnets breaking loose and taking out the stator.
Here is a link to a service bulletin on troubleshooting the system.
http://www.boatfix.com/merc/Bullet/83/83_08.pdf

You are going to find that no matter what part is bad, it's going to be more cost effective to replace the whole system with an alternator conversion kit.
I know the pulley with the magnets is NLA, and I thing some of the stators or regulators were also.

Re: Mercruiser 3.7L 1986 charging problem

I purchased a alternator kit from Breezeworks. They have a new 3 wire alternator kit for about $300.00. It is cheaper than replacing all the original and hopefully it will solve the problem.
This winter I am going to pull the engine and rebuild. I just want to enjoy the water until the weather gets cooler.

Re: Mercruiser 3.7L 1986 charging problem

tsr966,

You mentioned that you have power steering. Is this a hydraulic pump on the front of the engine with a fan belt driving it? If so, you're going to have to come up with a way of running 2 belts. The external alternator kit everybody is talking about uses the groove on the front pulley that is currently being used by your steering pump....

Chris...........

Re: Mercruiser 3.7L 1986 charging problem

which kit did you get the high mount or the low mount, the low mound should work with the PS pump.You can run both off of one belt.