Last summer, my 1997 Mercury 115 2 stroke did something nasty to me. We were out for a picnic. As the tide was running out, I started the engine to head home. But there was no way to lower the engine. The tilt switch appeared to be dead on "down", and actually worked only on "Up". I mooched a tow from another boater and took a closer look at my engine the following day. I suspected a faulty trim relay, but dropped the idea after noting that both the Up and Down relays gave a healthy click. And that's where I started jumping to the wrong conclusions. I pulled to boat out of the water (and spoiled the end of my vacation), and did something stupid. I opened the trim motor, suspecting a faulty carbon brush. Nothing wrong there, Absolutely clean and dry. This was begging for disaster because the trim motor has tiny O-rings and they are best left undisturbed for a lifetime (fortunately, I can confirm, now that the boat has been back in the water for more than a month,, that I had successfully managed to close the unit without causing any leak). So I changed the two relays, regardless of their healthy clicking... and everything works fine again. What happens is that a relay can have a perfectly good solenoid, but fowled power contacts. The strong current required by the trim motor just can't get through the messy copper contacts. Cost of repair: about $20 per relay...
Faulty conclusion N?2. Before dropping my boat in the water at the start of this season, I hooked up the muffs in my backyard, fueled the tank and everything started beautifully. When I actually got to the yard to lower the boat, the starter failed on me. Click click, but no starter engagement. I opened the cowl, touched the starter solenoid, which sounded great when turning the key, but nothing more. In my head, I was already thinking that my starter motor may have given up on me, when one of the local mechanics at the yard happened to pass by. This guy made a 100% correct diagnosis in about three seconds. He told me that the starter relay had called it a day, and proved it by jabbing a large screwdriver between its two powerline poles. The engine immediately started, and all I had to do was buy a new starter relay (about 50 bucks) which was easy to install, even on water.
The lesson is: a relay, large or small, may be shot even if it gives a healthy clicking sound. The problem is that the inner contacts can foul up over a period of time, and actually insulate any passage of high-ampere current.
I hope my little adventures may help others to make the lower-cost, lower-trouble diagnostic before attempting repairs on things that ain't broken!
Faulty conclusion N?2. Before dropping my boat in the water at the start of this season, I hooked up the muffs in my backyard, fueled the tank and everything started beautifully. When I actually got to the yard to lower the boat, the starter failed on me. Click click, but no starter engagement. I opened the cowl, touched the starter solenoid, which sounded great when turning the key, but nothing more. In my head, I was already thinking that my starter motor may have given up on me, when one of the local mechanics at the yard happened to pass by. This guy made a 100% correct diagnosis in about three seconds. He told me that the starter relay had called it a day, and proved it by jabbing a large screwdriver between its two powerline poles. The engine immediately started, and all I had to do was buy a new starter relay (about 50 bucks) which was easy to install, even on water.
The lesson is: a relay, large or small, may be shot even if it gives a healthy clicking sound. The problem is that the inner contacts can foul up over a period of time, and actually insulate any passage of high-ampere current.
I hope my little adventures may help others to make the lower-cost, lower-trouble diagnostic before attempting repairs on things that ain't broken!
