1971 evinrude 85hp 85193a missing amp box

[1975 Chieftain]

Hello all, nice to be here!

I have seen a post from 2005 about replacing amplifier boxes on these motors.
From what I gather I need to use a 18-5749 on my motor, but I have acces to a 18-5748 amp new in the box for cheap.

The original amp was missing from the motor I purchased yesterday.

If these boxes are not interchangeable, are there other easily replaced components that would make it compatible?
I don't mind changing connectors and such, I just need it to be compatible electronically, and not physically.

Thanks in advance, looking forward to a prompt response

 

[racerone]

Re: 1971 evinrude 85hp 85193a missing amp box

Before you spend a penny on this motor you should evaluate the condition of the motor.-----Do a compression test.--------Check oil in the lower unit.----Check to see if the motor will shift out of forward to nuetral when you crank it over.---- Posting of pictures of motor also helps.

 

[1975 Chieftain]

Re: 1971 evinrude 85hp 85193a missing amp box

Before you spend a penny on this motor you should evaluate the condition of the motor.-----Do a compression test.--------Check oil in the lower unit.----Check to see if the motor will shift out of forward to nuetral when you crank it over.---- Posting of pictures of motor also helps.

That raises another question, I was about to check compression, but the motor is in gear.
It is of the electric shift type, and the controls are not hooked up as of yet.
Is there a way to put it in neutral without it being hooked up?
And from what I read in your reply, am I correct in assuming that cranking the engine over by supplying battery voltage directly to the starter solenoid?

 

[boobie]

Re: 1971 evinrude 85hp 85193a missing amp box

Take the prop off and then turn it over to check your compression. It won't shift into neutral until you get the wiring harness hooked up.

 

[1975 Chieftain]

Re: 1971 evinrude 85hp 85193a missing amp box

using the starter motor?

 

[racerone]

Re: 1971 evinrude 85hp 85193a missing amp box

Those lower units will shift from forward to nuetral after about one turn of the flywheel.------Controls hooked up and push button for nuetral pushed down.----The motor will always be in forward when not running.----It must turn so that oil pump provides pressure for shifting.

 

[1975 Chieftain]

Re: 1971 evinrude 85hp 85193a missing amp box

Thankyou very much, im heading out right now to do so.

 

[F_R]

Re: 1971 evinrude 85hp 85193a missing amp box

If I am not too late, cranking it with the wiring / battery disconnected can destroy the alternator rectifier in a heartbeat. It could also destroy the amplifier (if you had one). You should never attempt starting or cranking one of those motors without everything properly connected unless you know exactly what you are doing.

 

[boobie]

Re: 1971 evinrude 85hp 85193a missing amp box

F-R, how's he going to hurt anything if he's just turning it over with the battery and nothing else is hooked up ??

 

[1975 Chieftain]

Re: 1971 evinrude 85hp 85193a missing amp box

I cranked it over, but couldn't hook the wiring up, the ignition switch is missing from the controls.
I didn't know how long the engine had been sitting so I squirted some motor oil in the spark plug holes.
I know that this has falsified the compression test, but at least I know that all the cylinders are equal at 150psi.
The engine didn't shift into neutral though.

 

[boobie]

Re: 1971 evinrude 85hp 85193a missing amp box

You have to have power going to the lower unit and the motor turning over for it to go into neutral.

 

[Joe Reeves]

Re: 1971 evinrude 85hp 85193a missing amp box

From what I gather I need to use a 18-5749 on my motor, but I have acces to a 18-5748 amp new in the box for cheap.

To answer your original post/question..... Are you sure that those part number aren't instead 18-5709 and 18-5708 which is what I find in my Sierra catalog?

Now, 18-5708 is equivalent to the OMC/Bombardier three (3) wire rectifier(#583408) which is what your engine calls for.

And 18-5709 is equivalent to the OMC/Bombardier four (4) wire rectifier (#581778) which will in no way work on your engine.

 

[1975 Chieftain]

Re: 1971 evinrude 85hp 85193a missing amp box

I can confirm that the part numbers I used are the right ones, as I saw them on the amp boxes themselves, perhaps they are a current version of your original part numbers.
I just checked on the web and your numbers are for rectifiers, not amplifier boxes.

 

[Joe Reeves]

Re: 1971 evinrude 85hp 85193a missing amp box

I can confirm that the part numbers I used are the right ones, as I saw them on the amp boxes themselves, perhaps they are a current version of your original part numbers.
I just checked on the web and your numbers are for rectifiers, not amplifier boxes.

Okay, my error. I have no idea why I was thinking rectifier. However, now at least everyone else knows the rectifier scenario.

Getting to the Amplifiers.... (18-5749 and 18-5748), it's been my experience that the two will not interchange.

As far as throwing the lower unit into neutral if that's what you want to do, simply throw 12v to the green coded shift wire that leads to the lower unit at the powerhead area.

 

[1975 Chieftain]

Re: 1971 evinrude 85hp 85193a missing amp box

Thanks for the tip!

 

[racerone]

Re: 1971 evinrude 85hp 85193a missing amp box

To shift this motor.---Take out the sparkplugs------Set battery beside the motor.----Hook NEG to gearcase.---------Use small jumper wire and put POS 12 volts to green.---Turn flywheel with a socket and lower unit will go into nuetral after about one brisk turn.

 

[1975 Chieftain]

Re: 1971 evinrude 85hp 85193a missing amp box

Thanks for the tip!
Im on a steep learning curve!