Engine Wiring Harness | Boat Restoration

Mercruiser 3.0 Engine Wiring Harness Ratsnest

Video at the bottom if you’re like me and don’t like to read. LOL

Okay guys, so if you have read this blog you know that the mechanic left us with a mess. The first thing we are going to tackle is the rat’s nest of a wiring harness. If you’re ever going to work on wiring, make sure you label and take pictures, or you may spend hours doing research.

Engine Wiring Harness Repair Tools

So now that you have everything label “Unlike Us”. lets over the tools we used for this part of our boat restore project. We use the tools below for almost all wiring we do except house wiring. Not having the right tools for the job can not only be a pain, but you can really damage things or hurt yourself trying to make due with what you have. Spend a little extra here and get the right tools and hardware.

Good crimping tools set can save you time, and make sure your connections are right. We have used the cheaper wire stripper crimp combo, it will work in a pinch but would not want to trust it for a boat.

After you have good tools, quality butt connectors are a must, then cover the wires with wiring loom. The butt connectors we used have heat-shrink ends with glue, preventing moisture from causing damage. The heat gun we used for our butt connectors heated very quickly making short work sealing our wires.

Finally, we always have a multimeter, troubleshooting wiring is hard enough. You don’t have to break the bank for a multimeter that will save you a headache working on wiring. Most cheaper ones will fit the bill for repairs.

Almost forgot, if you are working on the Mercruiser 3.0 Engine Wiring Harness your going to need a diagram, here’s the one I used.

Tools used:

Heat gun: https://amzn.to/2ykUqzq
Crimping Tool Kits: https://amzn.to/2ym6a4V
Butt connectors: https://amzn.to/2C3lhUk
Heat Shrink: https://amzn.to/2pFWiit
Wiring Loom: https://amzn.to/2ykwtII
Multimeter: https://amzn.to/2COY2hX

Mercruiser 3.0 Engine Wiring Harness Cleanup

The first thing we had to do is get all the electrical tape that the mechanic had wrapped the wires in. This seems really easy in the Bayliner 175 cause it quickly disconnects so we could take the wiring harness down to our workbench. The reason we use wiring loom and not tons of tape is the loom will protect the wire and makes it easier to repair future problems.

Once all the tape was off we could easily see and address wiring harness issues. This harness had areas that were left exposed wire splices were poorly done. Also, cause wire loom was not on the wires some had burned from engine heat or rubbed through, all this had to be taken care of.

Engine Wiring Harness Butt Connectors

You remember us talking about heat shrink butt connectors, well here they are and why they are important. Just look at that seal, this is much more clear in the video but we hope you get the idea. We don’t want to get stranded because and hope you would not want to get stranded either.

Engine Wiring Harness Loom

Loom or Doom that is the question, kidding but you do want to protect all your hard work. The engine compartment is not a friendly environment for your wiring, wires can easily melt or rub through cause engine failure or worse, a fire. Wire loom is very cheap and can save you so much heartache in the end, get it, use it.

Engine Wiring Harness Is Complete

When you are done your wire should look like below. I did not put all the wire loom on the wires because I want to fit it as I run it on the engine.

Next, We Install It

Stay tuned for the next entry as we install our wiring harness on the Mercruiser 3.0 Engine. Going to be a lot of fun, also check out the video below if you want to hear us talk through the installation.

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Commonsense provided by my love Danielle Redding.