1977 Merc 115HP Inline 6 (1150): Wiring Harness Questions

[kck8385]

I am replacing the wiring harness on my 1977 Merc 115HP Inline 6 (1150) S# 4689451and would like opinions/experiences/advice regarding the following questions.

1. Is there any difference in the OEM vs CDI vs Seirra wiring harness?
2. Does the CDI external harness come with "heat shrink tubing" on the wiring at the end of the plug to where it goes in the boat? The Sierra harness shows this but the CDI does not.
2. Would you purchase both the internal and external harness or just purchase the external harness, cut off the plug and wire it directly to the motor?

I have had this motor for 34 years and it is still running strong.

Thank you,
Kevin

 

[Chris1956]

If the boat harness is good, and the quick disconnect plug is good, just get the engine harness. Try the surplusunlimited web site for a good price. You will probably get the combo (battery CDI/ ADI) wire harness with the orange wire. On your motor, that wire is unused.

After 34 years, I am not sure if the heat-shrink tubing will make any substantive difference. The oem plug was tinned brass, and the Sierra replacement is just brass.

 

[kck8385]

Chris, Thank you for the reply.

The boat harness is what I need to replace. The insulation on the wiring is shot. Is there any quality difference between OEM, CDI or Sierra harness?

Thanks

 

[Chris1956]

Boat harnesses are a different story, and not nearly so readily available. My '77 Merc 1500 has tinned copper marine-grade conductors, likely identical to your harness. My '93 Merc 135HPV6 has plain copper conductors. Merc must have made the change somewhere along the line. The copper is working fine, as it is soldered to the controls.

Obviously the marine grade conductors are superior, but considering the age of your motor, I would go with the cheapest you can get. The harness will still cost you more than the motor is worth.

 

[kck8385]

Chris,

Thanks again for the information.