HELP HELP, charging system problem

[beachbum_59]

1984 Merc 470 4cyl. <br />Installed new battery 6-10-03 beginning of season. Volt gauge on boat ran about 12v above 1000rpm, held steady no problem, then this weekend noticed it was running lower around 10v, boat kept starting, thought new battery had just reached full charge, WRONG, dead battery at start attempt, visual check found broken wire on solenoid, a funny looking solid white plastic box attached to solenoid. Figured the broken connection was the reason for no charge. Fixed broken wire and Cranked the boat with trolling motor battery. Switched to regular battery with volts showing normal 12v output. Boat charged battery and following day had no cranking problems. About halfway through the day noticed volts at 16v on the gauge. turning on blower or nav lights volts drop but still stay around 13. WHATS UP WITH THIS?

 

[stub756]

Re: HELP HELP, charging system problem

I'd be happy with 13v reading. Im new to boating thogu so maybe its bad on boats. But one cars the higher the better typically unless some of your equpment cant handle upwards of 14.4v.

 

[galaxy]

Re: HELP HELP, charging system problem

Have you done a voltage check on the alternator?<br />Also, what was wrong with old battery?

 

[capercanuck]

Re: HELP HELP, charging system problem

I'm having charging problems also, but have repaired them. Typically a voltage reading on your dash mount voltmeter of 12 volts is not good. It should read 13.5-14.5v. Any higher or lower than that could mean problems. I did a search on www.google.com for "alternator troubleshooting" and I got a bunch of really good information. One site actually had a step by step printable sheet to test the alternator, batteries and associated wiring. You will need a handheld voltmeter to follow the steps. i used this sheet and found the problem within minutes. There was a broken wire in the plug attachment for the alternator. Repaired the plug and I was back out on the water that afternoon. if I can find the site again, I'll post it.<br />Good luck!

 

[elpaso]

Re: HELP HELP, charging system problem

A 1984 Merc 470 has no alternator. It has a <br />- stator - with a remote water cooled voltage regulator. Stator is located where a harmonic<br />balancer should be -on front of crank. Regulator is on port side of engine - water hose from outdrive goes through it in route to heat exchanger. Strange white box on starter solenoid<br />is a 90 amp fuse. Be very careful. The regulator<br />is $410. - the stator $435. only at Mercury.<br />I have a wiring diagram. But - I do not know how<br />to post it to this site. - Help .<br />Dealers call this engine - Mercurys Mistake.