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1993 300E 2.8
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329 Posts
Discussion Starter #1
I am debating if I should find the time to rebuid engine harness -- If I do, I want to replace every wire, insulate, heat shield etc. as some have successfully done here so it's going to be time consuming. Also I hate to pay MB any $$ to replace some crap-ass part they decided to put into this car.

I cut into the rubber molding at injection coil wires carrier and to my surprise it keeps crumbling further in as I go. For people who rebuilt: did you do w/o the rubber molding which is just a cable carrier?
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
I've built a few mini-harnesses in the past. I just use a combination of electrical tape and various sizes of plastic cable sheathing.



I suppose a guy could operate a decent side biz fabricating harnesses from all new wiring and connectors, and sell them for half what MB wants for these.
 

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'91 C124 300CE, '06 W164 ML500, '00 BMW MCOUPE, '65 COBRA REPL.
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547 Posts
Use heat shrink on each individual wire. The copper wiring is not the problem, the insulation is. Remove the old insulation (not much left from your pics). Electrical tape by itself will not last. No need to pay big $$$ for a fairly simple but time consuming job.
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
I suppose you could try and re-use the old wires, but that sounds like even more work than just soldering in new. If you can buy bulk shrink tubing by the roll, this might make some sense.
 

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1993 300E 2.8
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329 Posts
Discussion Starter #6 (Edited)
Use heat shrink on each individual wire. The copper wiring is not the problem, the insulation is. Remove the old insulation (not much left from your pics). Electrical tape by itself will not last. No need to pay big $$$ for a fairly simple but time consuming job.

If I'm to heat-shrink each exisiting copper wire (w/o old insulation), then I will still have to remove ends from connector and re-solder back on the connector, right? -- in this case, don't we rather have new wires altogether? Yeah if am to just tape the copper with insulation tape, then I don't have to remove wires from connectors but as you said, somehow it doesn't give a good feel about the quality after all is said and done.
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
The nice thing about MB connectors is that they're soldered at the ends, and can be removed individually. This would be rather tedious, but doable. The other concern is that the heatshrink tends to make the wire a bit stiffer, and may increase the diameter as well. Like I said, if you can find bulk shrink tubing rolls in the size you need, this is a viable option. I'd still prefer to replace all the wires, but this is intriguing
 

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Registered
1993 230 TE.1999 om 606 td. and 722.6 3.2L,clk w208 1987 Kit car with 260e running gear.
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738 Posts
I did my 320 coupe harness repair when the engine was out and hanging on a chain.
Heatshrink like casey says. 1 metre lengths from e bay.
Did every injector wire and coils wires and some sensors. I didnt take any plugs apart.
Every wire was cut, one at a time and sleeved and oversleeved and each cut staggered the next.
Wires were soldered together again with a butane mini torch and multicore solder. Suitable heatshrink (prefitted of course) over the wires and a larger one over the joint for them to go into.
Joints were lost in the tracks and cableways.
At the plugs I had the individual wires sleeved, as above, and a much larger short sleeve over them both.
I dont know if it matters but I was careful not to splice in any new cable because the engine management system might be sensitive to the resistance of wires as existing. Dont know, just took no chances.

Boyd :)
 

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1993 300E 2.8
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329 Posts
Discussion Starter #9
Thanks for the input. Likewise, I'd like to use continuous wires and not have to join/solder them in middle for same resistance concerns.

I'm a bit confused. There is a p/n in epc for the rubber molded cable guide (p/n 124 546 09 80) -- anyone know how this part comes? When I look at the old one, it seems glued shut w/ cables in it. Is there a way to open the old one?

If I can't figure how to put new wires through the old rubber guide, I may have to do away with it and figure something out. I can see how it helps coil wires stay in place under vibrations etc.

One issue w/ making your own rebuild is that some connectors are not designed to be opened. So they have to be cut open, soldered wires to pins and then glued back shut. This is my understanding.
 

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W124 E420 : W220 S500 : W222 S550
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402 Posts
Epc show almost all of the actual connectors but not many plugs. I have an e420 harness with ASR hanging in the garage.

My plan is to replace every wire. But splice to the complex molded plugs and also replace any connector that I can. A lot of the basic 2, 3, 4 pin plugs are available

Be careful on the heat shrink, we must use an engine compartment rated heat shrink (resistant to glycols, oils, refrigerants, etc..)
 
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