Merc 500 50HP Thunderbolt. Wiring overhaul and timing belt question.

Roadblock

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Actually I just edited this thread. I have a timing belt question too.

How loose should the belt be? I can grab a hold of it and it's got a bit of back and forth flex. Are boat motors considered interference engines? What happens if the belt breaks? I will post a video of how much play it has later tonight. I know on my Mitsubishi Eclipse GSX AWD Turbo if a belt was this loose it would be like engine failure and probably rebuild time! :)

Now, on to my original question!

I just rebuilt my transom and obviously I had to remove the motor. I happened to notice that some of the wiring looks less than safe! After inspecting all of the wiring, it's pretty much ALL shot.

Almost every wire inside of the engine is baked. What I mean is that all the wiring coating has been repeatedly heated and cooled so many times that its all rock hard and cracked. Obviously it's been cracked for some time because when I pull pack the wiring casing ALL of the wire is corroded and has a green powder like crap inside of it. I've got some hole shot hesitation and I'm wondering if this might be why.

I traced all the wires from the harness that plugs into the side of the motor to where they end, solenoid, starter, alternator etc and ALL of them are cracked. Then also all of the connectors and screw down points are rusted on everything too. Those I can probably clean up and put new nuts on etc but I'm shocked this thing even runs.

I assume I'm going to have to make most of this wiring myself? What would be a good type of wire to use and what type of connectors. Unless I can buy this wiring still? I don't know.

One of the things with a bad wire is this small thing mounted to the right of the throttle and shift arm, what is that and can it be repaired or replaced?

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GA_Boater

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You can get a replacement CDI motor harness right from iboats. The black cylinder with the two wires is mercury switch to stop the motor or keep it from starting if it's tilted up very far.
 

Roadblock

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The internal wiring harness, not the external one?

So that switch is like a mercury filled switch or has some type of moving part in it that completed the connection when it's sitting normal? Does it also serve as a kill switch if the boat rolls over or tips in the water then?
 

Roadblock

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Scratch that, I found it.

I Googled it, found it at another dealer and then used the manufactors part number from that site to search iBoats and found it. It's about $40.00 dollars more here on iBoats but I found it.

This might be easier than trying to rewire mine.
 
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racerone

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No such thing as an interference motor on a 2 stroke like yours.---There are no valves to interfere with the pistons.
 

Roadblock

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OK I wasn't sure one way or the other. I didn't know if the motor would explode if it dumped the timing belt. Ever seen what happens to a 500HP 4 cylinder at 10,000 RPM's when the belt goes? We left internal engine componets all over the highway so I thought I would ask! :D

Thanks guys, I'll have to get one of those wiring kits ordered! :)
 

racerone

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This timing belt drives a distributor only.----There is no camshaft and there are no valves in the cylinder area.
 

GA_Boater

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OK I wasn't sure one way or the other. I didn't know if the motor would explode if it dumped the timing belt. Ever seen what happens to a 500HP 4 cylinder at 10,000 RPM's when the belt goes? We left internal engine componets all over the highway so I thought I would ask! :D

Thanks guys, I'll have to get one of those wiring kits ordered! :)

Verify by your serial number, but I'm sure the harness is the right one.

To ease you mind a little more, I know what happens when the belt breaks on a 500 Merc. The motor stops - That's all.
 
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