I'm trying to keep my daughter's '84 240 wagon alive 'til spring. I just purchased it a month ago, with about 100,000 miles on the odometer. Engine runs strong, good brakes, good suspension. It seems just about everything else has been neglected. I am prioritizing my jobs, and the car has a good deal of potential.
It starts up, runs well, and just passed inspection.

My worry is the terribly degraded insulation on the engine wiring harness. It seems that the driver's side of the harness is in very good shape. I thought of purchasing a harness on ebay, but they've been going for $200 used. That seems pretty steep.

My question is, do I need both sides of the engine harness? I was thinking of replacing the one side with the best automotive wire and connectors I could find.

Your opinions would be appreciated~

Thanks in advance,

Larry

It is an easy DIY project, (couple of hours), if you don't care about appearance.

Just replace one wire at a time. The gray plug has small gray plates on either side that pop off and allow you to access the wires individually. If you slice through the loom/sheathing that the wires are in, you'll be able to trace and replace each one seperately.

The bullet plugs in the gray connector may be hard to find (dealer has them for 50 cents each?) so when you make the cut leave enough wire on the plugs so that you can attach replacement wire. I used blue crimp-on butt connectors, instead of pink, as they fit over the plug ends. I also sheathed the wires individually with teflon polytube (hard to find so could use vinyl tubing found in small diameters in hardware stores for fluids as they're heat and oil resistant). Reroute some wires (eg oil, alt) and bundle them together with zip ties.
--
1980 245 Canadian B21A with SU carb and M46 trans

I replaced all the worst offenders on the harness of my 86 240 by cutting out the bad, and splicing in with auto grade 16ga wire, soldering new connectors, using heat shrink tubing to seal the ends and then re-covering the whole mess with hi-temp spiral wrap. I fully intended to just have it make do until I could get a new or better harness and replace the whole thing. But it has been fine for a while now and has not seemed to get any worse.She starts and runs fine even in the cold ( knock on wood, top of head), and the front struts and rear suspension bushings have moved up and passed it on the the must do list.
--
'94 940 150k, '86 240 170k, '72 142 KIA, '70 144 KIA, '69 144 RIP

the harness on my sons 85 looks terrible, i have a spare but im not messing with it as long as it's not giving any problems. i did repair the big red wire going to alternator. good luck

Driver's side of gray connector in engine room is usually OK. You must follow same advice given to Physicians: First, do no harm. Don't touch the wiring unless you can safely follow through on a repair. Simply bending the outer sheath of black plastic might damage the decomposing plastic coating on individual internal wires, causing a hidden short or confusing the computer. In four or five hours you can remove manifold, slit the black plastic covering with a SHARP Xacto blade and re-cover EACH wire with electrical tape then pretty it up with split-loom. Not hard work, just slow and careful.

That particular upgraded engine wiring harness can often be bought for about $75 used, I'd replace the entire harness instead of repairing the old one.

Also, look carefully at the wiring harness for the ignition computer. They are often bad if the engine harness is bad.

I bought both harnesses at a self serve wrecking yard, and spent $20.
--
john