Starter Wires Keep Popping Off

[truckman]

Gents, I have been having an ongoing problem with my 05 Catalina 310. I have had the boat only since this past Sept. and have had the spade connections fail on two occasions both from the oil sending unit and another come loose from and fall off from another and the output from the alternator simply break off at the connection to the connector on the starter. I know whats causing this.....viiiiibbbrrattattionnnnnn, but I am not sure about a fix. I have rewired and put new spade connectors on and have had them vibrate loose. I am thinking of adding additonal wire so there is a bit of built in shock absorbancy. Has anyone had these problems and if so what is the best fix. The spade connections seem to be a weak link. I did buy high quality ones so if anyone has any ideas I am all ears.

Thanks in advance, Dave

 

[Shell]

This happened to my friends Benetau. All wires leading to the engine should have extra length. Not straight and tight. By having a curve, the vibration is not transmitted directly to one point of a wire but is distributed through the curve of the wire. Another way to understand the vibration break is to use this example. If you wanted to break a wire with your bare hands, you would hold the wire with both hands, close to one point and keep twisting. Eventually it will break at that point. If you held the ends of the same wire of some length and kept bending, it would not break as easy. To some up, the wires need some play so the vibrating engine does not transmit the vibration to the same point of the wire. My guess the break near the connection point. Also, if you use crimp on connection make sure the lug is compressed evenly round not flattened. This makes the connection stronger. Check the wiring harness for any extra length that can be pulled toward the engine. On my friends boat, the factory had a curve of about 1 foot of harness behind a strap to the hull as opposed to having the excess from the engine. It took me 2 broken wires to figure this one out. After pulling the harness closer to the engine and giving the wires to the engine more play, never had a problem.

Good luck
SH

 

[paulj]

truckman

I rewired like this.

See you at the Seattle Boat Show class on diesel engines by Nidel.

paulj:troll:

 

[Shell]

Looks good Paul!

Enough play to keep constant bending at the connection points.

 

[truckman]

Shell, Thats good advice. I was planning on looking for more slack. Paul thanks for the pics. Did you have to take off your oil sending unit to drill the holes to change to ring connectors. Not much room over there as you know. I am going down to the boat right now and will look into both of your suggestions. If I have to add some new wire I think I will try to coil it for several inches to add some more shock absorbency to the wires. My other thought was to slide some shrink tubing down over the spade connectors and heat it up around the entire connection. Paul what day(s) are you planning on going to the boat show in Seattle?

Dave