70 Merc - Alarm/Corosion

[Grant Brown]

I re-did the waterpump in my 70 Merc 3 Cyl serial # 0A739874, the other night and had a look under the 2 plastic covers on either side of the leg just above the lower unit. The bolts under there are very rusted and I noticed a broken bare wire with 2 lugs on it that looks like it was supposed to connect to 2 of the bolts. What is it's purpose, how important is it and is it worth trying to un-do the large rusted bolt it's supposed to connect to? Here's a picture (last one on the page)http://www.grantbrown.ca/boat/.<br /><br />Also this engine has seen some salt but it runs great and has always been well maintained. Is there anything I can do about the corosion on the leg?<br /><br />On another note, when is the alarm supposed to go off? Low oil, tilt, and temp, but is there anything else that sets it off?<br /><br />Thanks,<br />Grant

 

[Grant Brown]

Re: 70 Merc - Alarm/Corosion

Bump

 

[schaiss]

Re: 70 Merc - Alarm/Corosion

The wire you mentioned is there to keep a continuous ground potential from the powerhead of the engine all the way down to the skeg at the bottom of the engine. YES !!!! Whatever you do, be sure that this connection is reestablished. You do not have to use the same wire, but be sure to put another wire in to replace it which will bridge the joint you are talking about. Without this "connection", you will be exposing your lower unit to a ground potential which does not match the powerhead.

 

[Clams Canino]

Re: 70 Merc - Alarm/Corosion

Sorry,<br /><br />Totally dissagree. <br /><br />IF the motor is now being used in fresh water and especially IF using an ohm-meter the lower unit casing shows continuity to the leg (and it ought to via the bolts) THEN you are only risking damage by trying to loosten the rusted bolts.<br /><br />Sorry, but I say: "If it ain;t broke, don't fix it."<br /><br />-W (between homes but working on getting a place on Lake Hartwell)

 

[Grant Brown]

Re: 70 Merc - Alarm/Corosion

The boat will be used in salt water often.

 

[Grant Brown]

Re: 70 Merc - Alarm/Corosion

I'm going to try and solder the wire back on the luck on the large bolt. I'll check it every once in awhile and see what happens.<br /><br />Thanks again, Grant