How did I get home

[Dignity]

Have had problems with the Taco and never thoughht much about it - did do a post but as it wasn't too important didn't worry too much about it as I judged what was happening more by the sound of the engine. Had the last week on the water and it was become an annoyance after a while. Started to check the wiring starting at the taco and worked my way to the motor to find this.

[Dignity]

scorch marks and when I stuck my hand underneath a few more wires separated.

[Dignity]

There are 2 boxes behind this panel - here is a photo of the top one which appears to be in good nick - what are they? More importantly what would cause one of them to burn away like this.

[Roughasguts]

Any kinda short will burn wires. Only takes one to short then they all heat up and do plenty of damage.

Fuses are your best defence.

[Roughasguts]

Those two red wires are probably the culprit what are they attached too.

[finga64]

Can you give a picture from further out and what motor is it??
Lots of bad stuff/problems start as a crook earth. The two wires earthed in the picture don't look so hot :P

[Dignity]

roughasguts - the two wires come out of the same sort of box as is shown in the last picture only towards the bottom of the motor.

finga - sorry, wasn't thinking as I was in a hurry to get out and change a couple of wheel bearings before it got too hot - inyerestingly enough the one I thought might be going was ok but the other which I thought was good was getting a little crook. Still 2 wheels to go. The motor is a 1991 150 hp merc. Will get another picture later today but all are of the rear end of the motor, the first 2 at the bottom and the last at the top as the square box looks to be the same as the the bottom one which is burnt.

sam

[Roughasguts]

Dignity, think I would cut and shut all those wires with solder and heat shrink.

Then remove and clean up, and put new terminals on that earth.
Run the motor and feel those wires for heat, it won't take long for them to get hot if theres still a problem.

If no heat or electrical smell then no more problem.

Keep some spare bits of wire in your boat and terminals just in case.

I have no idea what those plastic boxes are.

[Dignity]

RAGS - thanks #for the info, was thinking much along the same lines until I went out to take another pic and had a closer look ( last night it was getting dark and I had a few beers). #Found more wiring burnt than originally thought. #here is new pic.


sam

[Roughasguts]

Sam it might look bad you just need to replace one wire at a time.

With those boxes check with a OHM meter resistance see if there all the same if not that box may be faulty.

Those burn't wires hard to tell from the piccys but they don't look real fresh. I think they have been cooking for quite a few trips.

Heat will melt the wire and strip it clean, hardly any trace left.
But fire will charcoal them and make them brittle, which does it look like to you.

[Dignity]

RAGS, the top wire looks charcoal and brittle most of the others look like they have been melting away. The square unamed box at the bottom had all charcaol where the wires went in - as I said earlier started looking at the taco wire and when I felt around that box the red wires just came loose.

Would agree with you on the cooking over a couple of trips although it looked ok when I came back in. Occasionally couldn't get the thing started and eventually replaced the fuel bulb which seemed to solve the problem except it happened again this week. Guess there must have been a loose wire all along.

sam

[finga64]

Don't know what the boxes are. Don't know that model at all.
If the taco is playing up you could assume one is a rectifier.
Be carefull about just changing/fixing the wires as wires usually burn for a reason. I'd be more concerned about find the reason so it doesn't happen again. Fixing the wires is the easy bit ;D
Be sure to continue with the colour theme though so the next guy hasn't the added burden of tring to see what wire goes where.
this maybe of interest
http://www.themarinedoctor.com/cgi-bin/YaBB.pl?board=MM;action=display;num=1165095749

[Roughasguts]

Sounds interesting I'm guesing here but think the box at the bottom has caught fire and charcoaled those wires. I guess theres windings in that box and the insulation melted through and shorted that box out.
so it's completly stuffed.

But I would still check it's resistance against another box.
So theres 4 of those boxes on a 6 cylinder motor ???
Don't know what they do, If there was 6, I would of thought a coil.

[Dignity]

There are only 2 of these boxes and they could be the regulators. It does lool like the bottom one caught fire and burnt. Bit I can't figure out is how I got home, started the motor to flush it all in the condition it was in.

Finga- understand the necessity for the colour coding but feel although I could save heaps doing up the wiring myself if I don't know what I am trying to fix I might as well get it done properly by a professional.

[Roughasguts]

Thanks finga for the link, must be a regulator then.

Out of intrest Sam do you spray the motor down with WD40

[Dignity]

no - use Lanotec - a lanolin based product

sam

[Dignity]

Finga, Roughasguts, futher close investigations shows that the bottom regulator caught fire sometime over the las t couple of days and it seems luck was on my side as I must have shut the motor down before it got a good hold - need to buy a lotto ticket. Wonder, does insurance cover that, there is currently an electrical storm raging, maybe the motor might get struck by lightning?

sam

[PADDLES]

g'day sam, i've got a 92 merc 135 which is virtually the same engine. ken lewis checked it all out for me when i bought it and apparently all mercs are wired with the wiring connectors bundled together with a cable tie, and nearly all of them heat up (at the connectors) and eventually flash through and create a short and a small fire if you're lucky enough. mine had a few scorched connectors which we replaced when i bought it. simple fix is to remove the cable ties and spread the connectors out to give them a bit of air between them. i'd be thinking that the short would have probably been what burnt out other stuff connected in the circuit. interestingly ken reckons that after all these years that mercury still tie all their connectors together.

[Dignity]

Paddles, food for thought, all the cables are pulled together using cable ties. Not sure that this is necessarily the cause. The bottom regulator has a big hole I can stick my finger in, mind you I turned off the power before I did that, as these cables are moulded in I suspect the cause could be something else as the connectors appear to be ok.

sam

[Roughasguts]

Dignity I don't know about the insurance, But with cars you can just get fire and theft. I wonder if this falls in this category.

So whats the plan now.
Still curious as always, are you running two batteries or just the one??

[PADDLES]

it's not the wires you have to worry about digga, the connectors are the "weak link" and they heat up if there's a little resistance across the joint (which there always is) and that soft insulation that's over the connectors simply melts and it eventually will flash through. seeing this opened up both my eyes and also my mate's (who sold me my boat). this is where getting an experienced mechanic to service ya boat has paid off for me, my connectors were all burnt and ready to go up. i'd check the other connectors in the loom dignity to see if they're ok too. ;)

[Dignity]

RAGS, 2 batteries but only ever run 1 at a time - I have a starting batery and a house batery.

Paddles - all the connections are still in good nick, it looks like the regulator decided to burn it self out, will take a much closer look at the weekend.

sam

[Dignity]

Update

Mechanics have no idea what went wrong. Theory is the Tacho stopped working some time ago and this meant one of the rectifiers was probably faulty. One of those jobs didn't think was important. Even though the 2 rectifier do different jobs if one goes the other one takes on a bigger load and evetually fails. Suspect this is what happened.

Roughasguts - The good news is that the insurance came to the party, even better news, I don't have excess. When I spoke to them they said they didn't pay on wearand tear, fair enough I was prepared to pay for the first recifier but then asked about the subsequent damage - they agreed to pay and ended paying the lot. The bad news is that the yoke is pretty well stuffed and have to get it fixed.

Paddles - all the connections were really good. They were sealed type and all of them were tighter than a drum. The resistance across them was better than expected.

Finga - agree about just changing the wires - turns out that if the wiring harnesses are of different resustance then you are guaranteed of problems down the road.


Some relays for the trim tilt still have to be fitted- waiting on parts but the original ones still work so I can get the old girl out now.
Sam.

[ryank]

hey mate.

when your tacho isnt working it mean ur bat is not charging which is usually caused by the rectifier shoring out.

good luck.