1979 70 hp Merc - Rectifier blown... what now??

[tipit008]

Hi,

Did not know what this thing was... only that it was clearly blown (melted plastic and wires around). I cross wired the battery and I've read that this will intantly kill this part.

What does this part do??

Is it normal that my engine (1979 70 hp Merc) is still running, although takes a while to start.

What damage could likely have been does because of running with this part burnt??

Thanks for any suggestions, answers.

Marc P.

 

[cannonford57]

Re: 1979 70 hp Merc - Rectifier blown... what now??

rectifier converts ac current from the alternator to dc the battery can use

 

[emckelvy]

Re: 1979 70 hp Merc - Rectifier blown... what now??

Just replace the part, or your battery won't charge. Theoretically there should be no other damage to your electrical system, as the ign is self-powered and doesn't even need a battery to run.

Look up the part at this site's Store, or go to your Merc dlr, they'll have it in stock. If you're closest to a NAPA store, they'll have a catalog of Sierra Marine replacement parts (with the NAPA name on them of course!) and they can look up an aftermarket rectifier for you.......ed

p.s. be sure to disconnect the positive lead on the battery before you replace the rectifier!

 

[tipit008]

Re: 1979 70 hp Merc - Rectifier blown... what now??

Thanks for the quick replies. I'll go to my local boat store this morning.

One question though about battery polarity.

I bought this boat used and the former owner had just replaced the battery connectors. When plugged with the red connector on the positive terminal and the black on the negative terminal, the starter would just spin and not engage.

When I inversed the battery wires, the starter worked fine. I figured that the former owner had just made a mistake in putting on his battery terminal connectors.

Am I right in making this assumption?? (the rectifier is burnt... so I know the battery was cross wired at least once...!!).

I just want to be sure so as to not burn the new rectifier I'm going to put on today.

Marc P.

 

[Chris1956]

Re: 1979 70 hp Merc - Rectifier blown... what now??

If the rectifier is burnt, it is bad. Switch the battery wires if you can or retape the insluation with red and black electrical tape so you do not switch them again.

Those rectifiers are available aftermarket in many places. A web search will assist.

BTW- the starter will run backwards if the battery cable are hooked up wrong, or if the magnet in the starter is unstalled upside down.