200 Optimax Wires melted??

Waterman · 03 January 2011, 14:09

Went down to the boat this morning hoping to go for a cruise. Had not been started in about 6 weeks and with all the cold weather knew the batteries would be worse for wear. Sure enough they were only reading about 11v and not enough to turn the engine over, I took the battery from the Discovery and swapped it with the starter battery. Tried turning it over (maybe for a 30 secs or so) then I saw smoke coming from the cowling?? Disconnected it immediately and lifted the hood. The insulation on the cables around the alternator were melted and the air filter was almost on fire?? Also noticed the positive on the solenoid was melted.
Hopefully just a few wires to replace but im baffled as to how it happened?? Battery was 12v and wired in correctly (+ and -) checked this a few times afterwards to make sure I hadnt crossed the battery cables?? and the Aux battery was disconnected.
Didnt think the rating was much higher than the normal starter battery.
Anyone any ideas??

chewy · 03 January 2011, 14:13

The motor would only take what current it needed.
By all means rewire it but find out what caused it before you try starting it again.
11v on a 12v battery is knackered.

martini · 03 January 2011, 14:20

I could well be wrong but I think I once read that starter motors and maybe alternators can create a short circuit when they are seized.

11v should've turned the motor over, my opti will although it won't power the ecu at the same time. If you put power to the starter and it can't spin then that can be a short (I think) and maybe same applies to the alternator.

Just a thought

Hightower · 03 January 2011, 14:50

Batteries themselves won't cause any problems with melted wires providing they are the same voltage and you simply swapped the two over. If you connected the negative to positive and visa versa then I would expect there to be built in protection to the outboard to protect it's self. So that just leaves the starter motor and alternator.

You said you tried to turn it over for 30 seconds. Was the starter not cranking the engine?

If this was indeed the case then it could be either a case of seized engine or faulty starter, both conditions that could draw more current from the battery (starter motor under heavy load or shorted) and so heat up the "weak link" in the wiring and melt it. There are not normally in line fuses on such power cables.

martini · 03 January 2011, 15:05

There's a fused link between the alternator and the slave solenoid which would pretty much eliminate an alternator issue, another finger pointing at your starter.

Waterman · 03 January 2011, 15:18

Thanks for replies guys, always great to get others thoughts.
Engine was turning over but it was like it wasnt drawing enough power to start, Voltage on the smartcraft gauge said it was 11.5v although the battery had come from the landrover and was definitely well above that. Starter motor was spinning fine just not enough to turn engine over (engine not seized). Never had a prob with the alternator before and was working just fine up to 6 weeks ago on my last trip, temp dropped down to about -16 C and rarely came above freezing during past few weeks so that would explain batteries but surely this wouldnt affect the wiring???
Still baffled??

jwalker · 03 January 2011, 15:37

Quote:

Originally Posted by Waterman

.... Starter motor was spinning fine just not enough to turn engine over (engine not seized).

Erm... something odd, this is not how the starter motor functions. If it's spinning but not engaging the engine there's a starter motor/solenoid issue. If it's engaging the engine and the engine isn't turning but you continue to hold the ignition start on, then it's not surprising you have melted the cable. A static starter motor will draw hundreds of amps with consequent heating. While cranking even a proper starting engine, the battery volts will drop close to 9v.

Hightower · 03 January 2011, 15:38

I thought some landrovers had 24v batteries. Or are these all on pre 1960 models?

chewy · 03 January 2011, 15:42

Quote:

Originally Posted by Hightower

I thought some landrovers had 24v batteries. Or are these all on pre 1960 models?

They were usually ex MOD FFR (fitted for radio). Not sure if they used 24v batteries or two 12v?

Even pre 1960 ones were 12v.

Waterman · 03 January 2011, 16:02

Quote:

Originally Posted by jwalker

Erm... something odd, this is not how the starter motor functions. If it's spinning but not engaging the engine there's a starter motor/solenoid issue. If it's engaging the engine and the engine isn't turning but you continue to hold the ignition start on, then it's not surprising you have melted the cable. A static starter motor will draw hundreds of amps with consequent heating. While cranking even a proper starting engine, the battery volts will drop close to 9v.

Sorry, my mistake I should have said it was engaging and slowly turning the engine over, just not enough to start it. Looks like I may have caused it myself by keeping it turning over for too long, although I have definitely turned it over for longer before without this happening.

jwalker · 03 January 2011, 16:11

Quote:

Originally Posted by Waterman

Sorry, my mistake I should have said it was engaging and slowly turning the engine over, just not enough to start it. Looks like I may have caused it myself by keeping it turning over for too long, although I have definitely turned it over for longer before without this happening.

The slower it's turning, the more current it draws. Most starter motors are unusual in the way they are wound compared to 'normal' DC motors; the field windings are in series with the armature windings. This has the effect of producing a very powerful magnetic field since there is very big current draw at the start of cranking when the motor is at its slowest and, consequently, a very high starting torque. For info, a motor wound this way will spin in the same direction if its polarity is reversed, unlike the more usual DC motor.

DJS · 03 January 2011, 19:12

Perhaps stating the obvious but if the wiring damage is localised e.g. only in the vicinity of the alternator or starter it is more likely to be a short circuit within the starter motor windings or the solenoid. However it would be prudent to check the alternator just to make sure its not seizing up as this could overtly overload the starter (slip the belt of and see if it turns freely by hand) it is also worth checking the all the connections; especially the negative (earth). A lot of folk concentrate on the positive however if the earth is poor the system will look for an alternative and if this is a lighter wire then under load it can cause a rise in temperature and eventually fire. Im not sure of your location but if you not a million miles away I would be happy to turn up with the multi meter and high discharge tester and take a look at the complete circuit right back to the ignition switch!.

Cheers

PeterM · 04 January 2011, 13:27

I'd put the non starting down to the low voltage ,and the wires melting down to starter motor being too hot due to continued turning over .

The voltage thing I have had on my opti . Smartcraft says one thing , but the engine only gets a few V due to corrosion in the wires/switch etc ( mine had 5v despite the smartcraft saying 12.2v) - have a look.. its amazing how quickly things can corrode .. mine went from 100% reliable starting to 50% in about a month.

The corrosion was just too much to give enough V to start the ECU and turn the engine over as has been said.

The other option is the starting relay - on the stb side of the engine at the bottom there are a few in a row .. I was told all identical ( but dont take my word - look at the writing on the side) so you can swap them to see if its this. The others are for the trim motor...

Good luck !

Waterman · 04 January 2011, 19:41

Quote:

Originally Posted by DJS

I would be happy to turn up with the multi meter and high discharge tester and take a look at the complete circuit right back to the ignition switch!.

Cheers for the kind offer DJS. Probably not a million miles away but a fair few. Based in Galway. Having it looked at by an outboard 'guru' during the week so ill let ye know how I get on.

Im hoping it was as PeterM has said and just down to low voltage and overkill on trying to start!

Jizm · 05 January 2011, 07:58

Had a similar thing a few years ago on a Yamaha, held the starter on for too long and that coupled to a bit of a poor connection resulted in smoke and damage. Easily repaired though.

Waterman · 10 January 2011, 18:05

Had the alternator and starter checked by a specialist and turns out rectifier on alternator failed and caused it to arc, resulting in my melted cables. I was advised that a new loom may be the best option as a few cables in the loom were also melted!!!

Anyone know of a secondhand loom anywhere?? Quite the expensive item new!

Jizm · 10 January 2011, 18:29

Quote:

Originally Posted by Waterman

Anyone know of a secondhand loom anywhere?? Quite the expensive item new!

Probably best to look in the states....

http://cgi.ebay.com/ebaymotors/Mercu...item27b7cfa60c

http://www.iboats.com/Marine_Store/d...ring%20harness

Waterman · 10 January 2011, 19:06

Was just searching good old ebay!!

chewy · 10 January 2011, 19:11

Can you not cut the melted cable and splice new wires into the loom if only a couple are shot?

tmuenster · 10 January 2011, 19:28

Quote:

Originally Posted by Hightower

Batteries themselves won't cause any problems with melted wires providing they are the same voltage and you simply swapped the two over. If you connected the negative to positive and visa versa then I would expect there to be built in protection to the outboard to protect it's self. So that just leaves the starter motor and alternator.

You said you tried to turn it over for 30 seconds. Was the starter not cranking the engine?

If this was indeed the case then it could be either a case of seized engine or faulty starter, both conditions that could draw more current from the battery (starter motor under heavy load or shorted) and so heat up the "weak link" in the wiring and melt it. There are not normally in line fuses on such power cables.

I have a couple of Opti's and had a similar problem with a 200hp opti sport jet motor. It had been flooded with water, which is a whole nother story. However, the wires were smoking and the engine was barely turning over. I used a wrench on the flywheel (Not sure if that is the correct term but the geared wheel at the top of the engine) and cranked it over manually a few times to purge the water. I poured some fuel down the intake and cranked it over. It caughed and sputtered but it started and eventually ran just like new. Those Opti's can take some abuse!

I would take the air cleaner off and look down the manifold for water or fuel. If you manually crank it a few times it should clear anything that is preventing it from starting.