Best tape for engine harness
 

I'm re-wrapping portions of my engine harness (realistically, it will probably be the whole thing) and I'm wondering if there is a preferred tape to use.

I have a few rolls of 3M Super (don't remember exactly which) electrical tape that has served me well, but I'm concerned about long term longevity since it gets pretty hot under the hood. My current plan is to remove all old crusty tape, clean the wires below, use split-loom to cover them, and then wrap with the electrical tape. This way if the tape gets gooey over a long time, it doesn't get on the wires themselves. The only time the tape will be on the wires will be at the juncture where they split from the main harness.

I searched around and found that some people recommend "loom tape", which looks like a fabric style tape. All of the loom tapes I've found so far seem to be rated for interior use, not under the hood. I also know there are vulcanizing tapes, but then you have to cut them off rather than peel if you need to alter something.

Does anyone have recommendations for a better tape for this application, or should I just use the 3M Super? Any advice is also appreciated.

I've looked into this before. Electrical adhesive tape is not recommended. As you've stated in your post, either non-adhesive plastic or fabric loom tape is used. Lots of the German cars used the fabric loom tape. Another option is braided split loom. You might have already this article, but here it is: https://grassrootsmotorsports.com/fo.../147248/page1/

Yes, you don't want electrical tape for this application....been there, done that. Makes a mess when you need to service the harness and there is glue everywhere.

Tesa is the company that makes all the harness tapes. The fuzzy tape you're referring to is their interior tape to prevent buzzes, rattles, and minor abrasions. Their 51026/51036 tape is what is rated for under hood. It is a different material and much more robust and heat resistant, but also more rigid.

Tesa's Most Advanced High Heat Harness Tape 51036 Mercedes, BMW, Audi, VW

silicone self-fusing tape

https://www.3m.com/3M/en_US/company-...2437112&rt=rud

i've done a bunch of harnii and Mazda uses (well they used Yazaki to make the things...) a plasitc tape that has some adhesive to it, but its not very sticky at all. you'll see as you unwrap yours, but they wrap it in this stuff like a bandage, and then the end gets secured with a sticky tape like the 3m stuff. i've loked a little for the not so sticky wrap stuff, and haven't come up with much, i end up reusing it a lot actually

sensitive areas get something like that self fusing stuff, and then sometimes a plastic sheath/conduit

That was actually one of the threads I'd found where I learned about loom tape, but thank you :) I was having a lot of trouble finding the engine bay type, and not the fuzzy interior type.

Thank you! That was exactly what I was looking for, for some reason I couldn't find it on Amazon.ca. I can still order through .com, so I placed an order. This one looks more woven instead of fuzzy, which I assume helps with fluid resistance.

I've heard of this type, but I was concerned about having to cut it in the event you have to unwrap the harness. It isn't very expensive though, so I placed an order for two rolls and I'll see what it's like. Thank you.

I noticed this as I was taking it apart, some has split loom, some is sticky tape, and some is the plastic type material that you mentioned. Since my harness is pretty crusty, I don't think I'll be able to practically reuse the plastic material. Most of it cracked off while I was cleaning it, it definitely won't come away cleanly. Thanks for the info :) I have quite a bit of split-loom, so I can use that to replace the old sheathing before I tape it.

Since neither tape was too expensive (and I'll end up finding a use for them someday, even if not for this project) I ordered a couple rolls each of the Tesa tape and the self-fusing tape. I'll test each and see if there's one I prefer. I'm also going to need to re-wrap the body harness, so I may use the self-fusing on the body harness (where water and dirt is more likely) and the Tesa on the engine. That way I can unwrap the engine harness without cutting the tape in the future. Thank you everyone for the input, I'll report back when it arrives (though regrettably that won't be until mid-May at the earliest).

Non-Adhesive Harness Tape

Friction tape from Home Depot. It’s self adhesive. Just wrap it tight.

i'm working on a harness right now, and i've just noticed some things that they did with the old one.

firstly the main branch is twisted a little, apparently twisting the wires makes the harness more flexible. so they do it, but its a gentle twist, sometimes they use this twist to help it go around corners too.
if there is a branch with only a couple/few wires, this gets twisted tightly near each end.
the larger branches get pieces of white tape every 6" or so, i think they lay out the thing, and use these guys to keep it together. some harnii get a plastic corner turning piece, if it is a tight/specific bend.
the wires that branch, like the injector power are crimped, and then the crimp is wrapped in what looks like a shrink wrap tape.
if there is a branch in a sensitive area, it gets an orange silicon wrap, its a lot like the self fusing stuff linked above.
any straight bit gets a sheath, sometimes these are a tube, and sometimes these are a wrap.

after all this, its wrapped with tape. i think the tape has a little adhesive in it, but its nothing like the 3m stuff. they use something like the 3m tape on the ends.

and then sensitive areas can have another sheath over them, usually the corrugated stuff.

So after working with both tapes, I have to say that I prefer the fabric Tesa tape over the silicone self-fusing tape.

The self-fusing tape is shinier and kind of pops out in the engine bay a bit. It's also a hassle to wrap around the harness because it's, well, self-fusing. So you need to unroll it while maintaining tension and also unwrapping the plastic backing that prevents the tape from sticking to itself on the roll. It basically requires three hands.

It's worth noting that the stock tape on the harness is not shiny, so it's possible that the tape loses that over time or that I simply found a different type of tape than what was originally used.

As for the Tesa tape, it's more expensive and harder to find (the listing I got mine from was an Amazon store in Latvia?), but it doesn't jump out at your eye in the engine bay and can be used basically like normal tape. I find the ends like to unstick sometimes, so use a zip-tie or similar to hold it from unravelling.

I can't speak as to whether one or the other is better for heat / fluid resistance, but since I have both I'm probably going to finish wrapping with the silicone first and then Tesa tape over it. So which is more resistant won't really matter in my case.

Thanks everyone for the advice :)

I agree with your comment about Tesa.. in particular I used the tesa 51036.

Personal opinion here...I've always just done a light wrap with 3M Super 88, then installed split loom, then wrapped again with Super 88. Can't ever recall having to open a harness after wrapping, so not sure about any sticky glue. Looked at my own car just now and 12+ years later no harness wrap issues.

Doesn't look OEM, but then again neither does anything else in the engine bay because it isn't.