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grizzreaper

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I picked up this 1985 glastron boat for the motor and outdrive.i am looking for the year so I can figure out the wiring . Pic#1 is the engine mount tab n the mercruiser serial is 5012180 which I looked up n there is no information. Pic#2 has a serial number by the wire harness 5003045. rest of the pics have a plastic tube coming out of the shifter I assume that's what it is. Different from my other motor which I have already pulled out. Hope someone can help me. Thanks in advance Paul
 

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alldodge

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Engine serial number should be on a plate above the starter
Didn't mention what motor

Being a 85 I would use manual 8 for 470, or 10 for 4 cyl
 

thumpar

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With those serial numbers your looking at a 1978 possibly 1979 motor.
 

grizzreaper

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It's 3.0 mercruiser 140 HP with outdrive that has powertrim on it.
 

alldodge

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With those serial numbers it would put it at pre-82 so manuals 3 and 4.

You might be right, so far I haven't seen a sn plate and he was saying 85. I'm just waiting for more info
 

thumpar

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You might be right, so far I haven't seen a sn plate and he was saying 85. I'm just waiting for more info

The pictures show the plate and tag, although you can't make them out in the pic he lists the numbers in the original post. The numbers look like legit serials and fall in the late 70's ranges. Judging by the looks of the wiring it would not surprise me if the motor had be swapped to something older than the boat.
 

Bt Doctur

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the plastic tube you mention is a reverse lock assembly and is hooked up to the trim pump,
 

achris

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Here's an extract from the Merc year/serial number chart. You'll see that for year 1978, MCM140 engines started at serial number 4918570, and for year 1979 they start at 5157669, so your engine falls into year 1978.... (and confirming that year of the hull may have nothing to do with year of the engine and drive.)

That will also make the drive an MC1, and the photo of a reverse lock valve confirms that.

Use service manual 3 for the engine, and 4 for the drive...

Chris.......

year.JPG
 

grizzreaper

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ok thank you everyone now my question is my motor that I took out is 1986 3.0 mercruiser with a Alpha 1 out drive. can I leave my gimbal housing, steering and trim cylinders there and put the 78 motor and outdrive in. thanks
 

Bondo

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now my question is my motor that I took out is 1986 3.0 mercruiser with a Alpha 1 out drive. can I leave my gimbal housing, steering and trim cylinders there and put the 78 motor and outdrive in.

Ayuh,.... A couple of things come to mind,.....

Ya gotta use the flywheel cover, 'n coupler from the '86,.....
Rear motor mount spacin' is different on the 2 covers, as is spline depth,....

'n the exhaust riser exit, may, or more likely, may not line up with the down-pipe,....
 

grizzreaper

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ok thank you for your reply. I have all winter to play with this.. still have to check compression on the 78 to make sure its worth my time to use it. thanks again to everyone.
 

grizzreaper

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OK Bondo or someone if my alpha 1 is a MC1 and the 78 is a pre-alpha but still a MC1 will the newer outdrive work if I switch the flywheel housing. Been thinking about this all morning. Thanks again>
 

Bondo

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OK Bondo or someone if my alpha 1 is a MC1 and the 78 is a pre-alpha but still a MC1 will the newer outdrive work if I switch the flywheel housing. Been thinking about this all morning. Thanks again>

Ayuh,.... What year/ vintage is the gimbel/ transom assembly are ya usin',..??..??

An '86 Alpha 1, is Not an MC-1,.....
The '78 will be an MC-1, which is slightly different than an Alpha 1, as I mentioned above,......
 

achris

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ok thank you everyone now my question is my motor that I took out is 1986 3.0 mercruiser with a Alpha 1 out drive. can I leave my gimbal housing, steering and trim cylinders there and put the 78 motor and outdrive in. thanks

Not recommended... There are significant differences between the MC-1 and the Alpha One gimbal and transom assemblies. Trim pump and hosing are very different, shift cable mounting is different, the inner transom plate is enough different so the engine WILL NOT mount to it.

If you have all of the 86, just replace the whole lot. In the end, it will be quicker, easier and present less problems in the future when it comes to repairs and replacement spares.

For an explanation of the different drives... (P.S. There's no such thing as a 'pre-Alpha') https://forums.iboats.com/forum/eng...utdrives/10596184-what-is-a-‘pre-alpha’-drive

Chris...........
 

grizzreaper

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Where can I find a wire diagram for the 78 3.0 mercruiser .wire 4 from what I can find is for the warning buzzer which this year never had or it was optional. Looking on the net I see it should be for alternator. I is a a red wire n same thickness as the power wire . Thanks again for any n all help
 

achris

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Where can I find a wire diagram for the 78 3.0 mercruiser ....

You have a voltmeter or an ammeter in the instrument cluster? And what colour is the wire on the oil pressure sender (orange or light blue)?

(The manual with wiring diagrams covers several models. With that information, I can find the right one for you)

Chris......
 
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grizzreaper

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I hooked up the black ground which is #1 on the harness. Then I took each single wire and a light tester.# 2 is a stright brown wire#3 is a stright green wire. #4 is a red with a white stripe this wire is thick like the ground. #5 is a stright white wire .#6 is a thick red wire again which goes to circut breaker. #7 is a stright yellow wire. #8 is a stright orange wire. #10 is a purple wire. I believe #3 went to the temp. Only a few wired were hooked up. Hope this helps n thank you
 
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