Sometimes it's the simple things

[ufm82]

I posted a while back about my Merc 150 overcharging. I saw the gauge go up immediately and cut the evening short so as to avoid ruining anything. I was miffed that no one had chimed in with any "specific" info but after being chided by several on here I apologized and went forward.
1993 Merc XRi that has the 40 amp system. Two regulators that are sandwiched between the switch box bracket against the engine. I was told that these were cooled by engine water and that they can be bad to deal with. I went in looking for the worst.
Upon my initial inspection, I found the wiring to be the issue. There are 4 wires to one regulator and 5 to the other- red and yellow and one grey. I found one of the yellow wires melted to one of the red wires and when I separated them, I found an ever so slight metal-to-metal contact spot. I could only guess that when hot it would short and full-field the staor- causing the overcharge. It only did it once and I do not think it caused any damage. I rerouted all the wiring, shrouded it properly so there could be no contact and put everything back together. Running in the driveway yielded 14.2 volts at all RPM up to 4,000. I haven't water-tested it yet at anything higher as yet but will do so this weekend hopefully.
Total repair cost? Nothing except time and frustration. This engine is 17 years old and this is the first real problem I've had since I bought the boat 4 years ago. It is clean under the cowl and this helped me find the problem quickly as I didn't have to muck through a bunch of goop to see what I needed to see.
So, a good visual inspection can solve some problems without having to dump a bunch of cash- take the time to look before you throw parts at something.

UFM82

 

[mrallen007]

Re: Sometimes it's the simple things

I second that. I recently bought a 1985 VIP bass rig with a 91 Merc 50HP. Test drive went great, of course. I took some close family friends out one Saturday morning to let the kids fish. I kept having throttle issues. The engine would choke out and die as I went into high rpm's. It died so much I killed my battery just trying to keep it running. Another boat happened by and jumped us off. Everything went fine for the next few minutes. With the other boat following, I had the confidence to try to do more than 5 mph or so. I gave it some gas and the engine quit. It didn't stall out, it's like it fell to idle and wouldn't move. The guy who jumped us off towed us in. We backed the truck, I pushed the boat onto the trailer from inside the lake, and we went home. A long frustrating day. The guy who towed me was an mmi grad. He said the water pump is toast. Another told me the charging system was clearly fried. Lots of expensive theories were thrown my way. So I went home and pulled off the cowling. The pin between the throttle linkage and the carbs was hanging there disconnected. Uh... Bad... The bushing that held it at one end broke and it just wiggled out. $6.50 later I had a new bushing and a corrected problem!

UFM82 is dead on. Keep your engine clean. Give it a good visual inspection before going on the word of else. Keep up your routine maintenance. Basic upkeep and sensible approaches will save you a fortune!

 

[j_martin]

Re: Sometimes it's the simple things

I posted a while back about my Merc 150 overcharging. I saw the gauge go up immediately and cut the evening short so as to avoid ruining anything. I was miffed that no one had chimed in with any "specific" info but after being chided by several on here I apologized and went forward.
1993 Merc XRi that has the 40 amp system. Two regulators that are sandwiched between the switch box bracket against the engine. I was told that these were cooled by engine water and that they can be bad to deal with. I went in looking for the worst.
Upon my initial inspection, I found the wiring to be the issue. There are 4 wires to one regulator and 5 to the other- red and yellow and one grey. I found one of the yellow wires melted to one of the red wires and when I separated them, I found an ever so slight metal-to-metal contact spot. I could only guess that when hot it would short and full-field the staor- causing the overcharge. It only did it once and I do not think it caused any damage. I rerouted all the wiring, shrouded it properly so there could be no contact and put everything back together. Running in the driveway yielded 14.2 volts at all RPM up to 4,000. I haven't water-tested it yet at anything higher as yet but will do so this weekend hopefully.
Total repair cost? Nothing except time and frustration. This engine is 17 years old and this is the first real problem I've had since I bought the boat 4 years ago. It is clean under the cowl and this helped me find the problem quickly as I didn't have to muck through a bunch of goop to see what I needed to see.
So, a good visual inspection can solve some problems without having to dump a bunch of cash- take the time to look before you throw parts at something.

UFM82

Perhaps you should ask instead of tell. I don't think anybody here told you that 2 regulators on the back plate would be water cooled. That's the standard dual regulator system, and yes, burned wiring is often the failure mode. The water cooled version is a big heavy water cooled thing over the exhaust divider with a single pair of 10 G yellow stator wires to it via a terminal strip.

The stator isn't "fielded" in any way. The field is provided by permanent magnets and not modified by any coil current anywhere in the system.

The overvoltage was probably caused by a regulator failing from the heat generated by the hot wiring. Keep an eye on it, it may happen again. If it does, just disconnect the yellow wires one pair at a time till you find the fault. The other one will carry you through the weekend. If you now have tight connections, the gremlin may never come back.

You wanted to get a quick answer to an unusual problem while providing no information as it is obvious you had not even looked closely at it. The reason you got no response at all is that this board is being "serviced" by a troll or trolls that put up ridiculous problems and then argue with and otherwise mess with folks that take the time to try to help. This looked like a troll cast.

Welcome aboard my friend. Be glad to help given full information about what you see and hear.