Mercruiser 260 battery/trim question

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bburnes

Recruit
Joined
Dec 12, 2010
Messages
2
I bought a 1987 Wellcraft 265 with a Mercruiser 260 and Alpha outdrive and I am learning my way around it. With a fresh battery, gauges come on and I can operate trim a few times. At some point when I press the trim switch I hear the trim relay click and the voltage gauge will drop from 12.5 to zero and nothing works. If I turn off main switch and let it rest for 20 minutes it "resets" and will work again for a few minutes. I thought the trim motor was pulling too much amperage from the battery, so I jumped my running truck battery to the boat. Same thing. Main circuit breaker for engine is not tripped. What is tripping?

Can't find this problem in the forums; thanks for your help.
 
redjmp

redjmp

Chief Petty Officer
Joined
Mar 16, 2005
Messages
536
Re: Mercruiser 260 battery/trim question

Your trim should cut out after about 17 degrees of travel upward to prevent damage to the ujoints. To raise the leg for trailering you need to push the trim up and trailer button together.
 
D

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,115
Re: Mercruiser 260 battery/trim question

you don't need to have the key switch in the "on" position to run the trim pump, just if you want to read the guage while operating the trim

try running the trim system with the key in the "off" position and see if the problem continues, if so then the issue is with the tilt/trim system

if the problem goes away, there is a problem with the boat/engine wiring system - possibly a bad guage or corrosion causing heat resistance somewhere - start at the battery and check all pos/neg connections and move down the line

it would help you greatly to get the OEM manual for your engine and check the wiring diagram(s)
 
B

bburnes

Recruit
Joined
Dec 12, 2010
Messages
2
Re: Mercruiser 260 battery/trim question

Fixed it! I started working through the whole electical system, taking connections apart and cleaning them. The battery negative looked fine and I cleaned it anyway. Still no power. Then I decided to unscrew the battery post connector on the end of the black wire. When Impulled it off the wire strands looked fine...until I turned it over. The bottom, where it actually contacts the battery post, was white with corrosion. I cleaned it with muriatic acid and coated with Anti-oxidation grease, like used in connecting residential
service line to breaker panel. Got a good connection
and plenty of amps. Thanks for you help!
 
redjmp

redjmp

Chief Petty Officer
Joined
Mar 16, 2005
Messages
536
Re: Mercruiser 260 battery/trim question

Acid and copper/electricity don't mix!

Acid will keep eating away at the copper until its gone when electricity flows!

Thats why you can use acid core solder for pipes but for electrical work you always use a resin core solder.

You need to neutralize that acid with baking soda and then flush with lots of water before putting on the grease!

One trick people use to keep their battery connections from corroding away is to put an unprotected copper penny on the battery as a sacrificial anode...
 
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