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Mercruiser to crusader

Jeff8330

Member
I am going to be buying a 1986 Sea Ray 300. The boat originally had twin 260s in it. A swap to crusader 270s was started. The motors were gone over. And installed. What is yet to be done is the risers and manifolds need to be installed, and the wiring harness. Here's my concern. The mechanic that was working on it said that harness for the mercruiser has an extra wire. Anything else on a motor, I can handle, but me and wires don't get along well. This is a pretty common swap I'm sure, everything else was pretty much the same. He had to have a bracket made up in order to mount the heat exchangers, but other than that everything pretty much went right in. Anyone know what I'll have to do with this harness ? Is it just an extra gauge or something ? The motors are 91 crusader 270s I believe. Thanks.
 
More info would be helpful.

Are these Merc Engines carbureted or fitted with FI?
Do you know why the Crusader 260 engine harnesses will not work, or do you not have them?
Do you know what the additional Mercruiser engine harness circuit is for?


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Sorry rick,
I am kind of getting this info as I go. I'm not sure if it was meant that the two pin connectors don't line up or what, in which case there is an adapter for mercruiser to crusader ilthat much I know. Anyway, the crusaders are carbed.

It had mercruiser 260s in it originally....it still has all the wiring from said motor. The new engines (crusaders) are also small blocks but I know the plugs are different. But the guy I talked to about the boat says there is an extra wire on the mercruiser harness that doesn't match up with the wires coming off the crusader. I haven't had a chance to look at it yet, but I do know the motors are in really good condition and they're low hour crusaders. Just going to need a little guidance in finishing up the install. It isn't necessary to swap out the entire harness correct ? I know they make adapters for this sorta thing, I've just never gone from Merc to crusader before. As far as the extra circuit, I do not know what it's for yet.
 
Are these engines providing power to outdrives? If so, the extra wire may be to momentarily kill the engine while shifting to neutral. I only know this from seeing it on a friend's boat.

Can you take a picture or two of the wires you're talking about? That will help the guys who really know Mercruisers.
 
The Merc standard harness is a round 10-pin entity and the Crusader harness is a rectangular 8-pin unit.

If the 91 engines' harnesses are in decent shape, I'd suggest it would be more cost effective to just buy new dash harnesses of the correct length, especially if wiring isn't your thing. No adapters, splices,etc - the minimum number of interconnects to cause you issues in the future.
I would also suggest an application of NYOGEL when mating the connectors as well as using a length of double walled heat shrink over the connector.

If the mercs are MIE and not MCM, there is not 'extra' wire.....
 
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They were mie. And I believe when he said an extra wire he meant 10 pin vs 8 pin. The wiring on the engine side is good. So you're saying it would be easy just to buy a new harness from the dash back to the engines made for the model crusader that now sits in the boat ? I mean, I can do basic stuff splice, read diagrams and stuff, I'm just trying to figure on the easiest route
 
If I went that route (new dash harness, beings it's twins, obviously I'd need two of em, and how do they tie in up front ? I apologize for my ignorance here.
 
Sorry u can't get pics right now, the boats in Jersey I'm in Florida. But I'll be going up to finish everything up at the marina and I'm just trying to see what I'm in for is all.
 
If the issue is connecting the Crusader engine harnesses to the original Merc hull harnesses, here is a replacement connector with wire harness extensions.

You would basically be building a new engine harness, following the Crusader wiring scheme.
It is not that difficult to do, especially if out and laying on the work bench!

This is through CP Performance Co.



This is through Basic Power Industries.







As an alternative, you could remove the OEM connectors altogether, and use a 10 gang terminal block.
These will provide a solid connection for all of your data circuits and your Positive and Negative circuits.
(actually, a more solid connection over that of the friction fit pins that Merc uses)


images


You would connect each circuit to the terminal block using spade terminals.


You can be creative and protect the terminals with something that is non-conductive and is water proof.






You would simply match colors for those that are the same between Crusader and Merc.

purple = ignition power
yellow/red stripe = starter motor solenoid
blue = oil pressure
brown or light brown = engine temp
gray or light gray = tachometer
heavy black = system Negative
heavy red = system positive

and so on.

While this may seem rather unorthodox, it will work, and would save the cost of the new hull harnesses and the labor to install them.

As for using the terminal block, you'd be on your own regarding whether or not it would meet USCG requirements.
I don't see an issue as long as you protected it.




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the 'dash end' would connect to the switch, gauges, and warning horn system.

The stuff that's in there now is decades old....that's why I'd suggest replacement. Change it out now and you shouldn't have to worry about it for a couple more decades...
 
Thank you guys so much for your guidance..... unfortunately like I said I'm just getting the boat and haven't had a chance to get into it yet. So I haven't really inspected the whole harness issue. It's probably not a big issue, but like I said I overthink it when I can't see it. Plus wiring intimidates me....if I get it right the first time I'm golden, if I screw it up though, it almost feels as though I'll never get it right.....and honestly I like your idea about the terminal block. Would be mounted back toward the engine somewhere and would basically just be an alternative to splicing the wires together if I'm not mistaken...that's an option. I'm going to ask around at the marina the boats at too. I just don't have the money to dump into the wiring issue. So I'd like to be able to figure it out .....again thank you guys.
 
My biggest thing is just being able to get the damn thing to run. I have a video of it running on a pallet, and I'm familiar with the no they came out of....they're great runners. It's a unique situation though. I am in florida. The boats in jersey.....I have a limited amount of time to work on them......I need to mount the heat exchanger, install the risers and manifolds, all the easy stuffm like I said my biggest worry is this stupid harness.....
 
............ and honestly I like your idea about the terminal block. Would be mounted back toward the engine somewhere and would basically just be an alternative to splicing the wires together if I'm not mistaken...that's an option. I'm going to ask around at the marina the boats at too. I just don't have the money to dump into the wiring issue. So I'd like to be able to figure it out .....again thank you guys.

That is correct!
While this is not an OEM style connection, your open spade style wire fittings and screw-down connections will make for better continuity due to the occasional issues with the OEM harness connector pins.
 
Thank you so much rick. Do you have any idea on colors variations as far crusader vs mercruiser wires back there ? It'd be nice if they were all a standard color (for say tach oil pressure etc) from mfg to mfg, but they probably arent.....I'll have a service manual by then, but for my crusader, not the old mercs..... However I would like to have as much info as possible ahead of time. Thanks again kind sir !!!!
 
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RE:.....

You would connect each circuit to the terminal block using spade terminals.


You can be creative and protect the terminals with something that is non-conductive and is water proof.






You would simply match colors for those that are the same between Crusader and Merc.

purple = ignition power
yellow/red stripe = starter motor solenoid
blue = oil pressure
brown or light brown = engine temp
gray or light gray = tachometer
heavy black = system Negative
heavy red = system positive

and so on.

While this may seem rather unorthodox, it will work, and would save the cost of the new hull harnesses and the labor to install them.

As for using the terminal block, you'd be on your own regarding whether or not it would meet USCG requirements.
I don't see an issue as long as you protected it.




.

Strongly recommend ring, not spade terminals, ALSO there are crimp terminals these days readily available at your local marine supply store that are MARINE grade and have heat shrink waterproof insulators... Re: terminal block as adapter... This works well providing you use marine grade blocks.
 
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Boat is in lanoka harbor. These crusaders are were maufactured in 91 i believe. They were rebuilt then the install was started and not finished. Its just this harness and the exhaust.
 
Bob makes a good point regarding spade vs ring terminals...... your call on that.




FYI....... the wire terminals with the heat shrink tube already on them must be crimped with the proper tool.
If not, the shrink tube itself will be damaged, and will split when the heat is applied. I've seen this many times. As tempting as they seem to be, I won't use them!





IMO, you will do better with bare terminals, and have your heat shrink tube already on the wire.
Make your crimp, slide the shrink tube over the freshly crimped fitting, and apply the heat.

 
Thabk you guys. As i saod, i can do wiring. I do have some experience with it, i just have a tendency to get frustrated real easy. When i get a chance to get to the boat and get going on it ill see what i can do. Thanks guys.
 
2x on rings vs spades....

He's gonna need a decent tool to crimp any connector properly....

aviation grade may be easier to find than marine grade for a terminal block....if its green next year, it wasn't either.

heatshrink usually requires something warmer than 212 deg F to fully 'shrink' - check the OEM's literature for the product selected to be sure....
 
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