replaced plugs, brittle wire loom falling apart

**howardc64** · 12-19-2005, 10:54 PM

When I moved the coil pack wire, the wire loom were very brittle and fell apart. I seem to have read other people observing the same.

What do you guys do? Buy new high temperature split wire looms to replace what is there or leave it as is. The wires that feeds the coil packs are definitely more exposed now as chunks of the wire loom fall off.

**al_roethlisberger** · 12-20-2005, 09:28 AM

Originally Posted by howardc64

When I moved the coil pack wire, the wire loom were very brittle and fell apart. I seem to have read other people observing the same.

What do you guys do? Buy new high temperature split wire looms to replace what is there or leave it as is. The wires that feeds the coil packs are definitely more exposed now as chunks of the wire loom fall off.

I don't know about Volvos, but all of my cars exhibited this issue as the cars got up in age.

Heat is the culprit, and some plastics just don't hold up.

Should you replace it? ...well, I guess it would be the best in due diligence.

Do you HAVE to replace it? ....well, I never did on my old cars, and never had a short *shrug*

I'd inspect where the loom has disintigrated and see if the wiring could scuff and possibly short out against any metal component. If not, then I'd say it isn't critical. If so, then you can go down to your local "Auto Kragen-Pep-Zone" store and buy some new split loom for about $5 and cut a small piece to slip over the disintigrating portion.

But all that being said, if you have an extended warrantee, I'd just roll the car into the shop, point, and say "please fix that fire hazard"

al

**howardc64** · 12-20-2005, 09:44 AM

Looking at what is there. Looks like I need at most is

1 foot of 1/4"
2 feet of 3/8"
1 foot of 1/2"

**1Lieutenant** · 12-20-2005, 09:56 AM

Had this happen in my 1999 XC at 30K! I was told this was a known problem. I would have thought they would have revised the material by 2001. Oh well.....

Steve

**howardc64** · 12-21-2005, 09:44 PM

Leaving some info for future DIYer

The split wire looms are typically speced as inner diameter in regular auto stores. So what appears to be 3/8 OD is actually 1/4 ID.

OEM wire looms have 3 sizes (1/4 ID, 3/8 ID and one smaller than 1/4 ID). I couldn't find anything smaller than 1/4 ID anywhere. So I used 1/4 ID all around. Even the wires originally in the 3/8 ID tube fit snuggly in the 1/4 ID tube without a problem.

Parts of the OEM tubes are wrapped in what appears to be electrical tape. Be sure to peel these off rather than cutting them if you want to remove these sections. Cutting action might be too close to the wires for comfort.

I did some research on the looms. It seems any split wire loom is going to be able to tolerate 200F of heat with some that can handle 300F. I got mine for 30cents/foot at the local electronics store (not auto industry stuff) so I would guess it is probably the lower temp stuff. I also used standard electrical tape to tape up some sections (so the wires don't pop out of the split)

After running a hot engine for 100 miles of continuous highway driving. The wire looms+tape survived just fine. No sign of any heat damage. Maybe they will get brittle some miles later just like the OEM stuff. Only time will tell.

**ChicagoXC** · 12-23-2005, 03:31 AM

I, too, have found a disintegrated mess of what used to be the loom. I had a dead coil and opted to replace it myself. (Of course, Volvo recommended replacing all of them. haha.) Anyways, my entire loom is gone.. visible now as hundreds of tiny pieces of plastic slivers all over the top of the engine.

I read the "go down to your local "Auto Kragen-Pep-Zone" store and buy some new split loom for about $5 and cut a small piece to slip over the disintigrating portion" but I tend to agree with Howardc64 about the temperatures.

My quick internet research showed that regular loom from the store is rated at 257 degrees F and that Polytetraflouroethylene loom (PTFE) is rated at 500 degrees F (260 C). I assume that 257 degrees won't hold on top of an engine AND that Volvo is using the higher temp stuff. Also, note that I couldn't find the hi-temp stuff anywhere that was pre-slit. Oh yeah, it's about $7 per foot

. Check it at http://cableorganizer.com/wire-loom/ptfe-wireloom.htm

I am considering replacing the whole harness from the nearest junction to the 5 coils. Likewise, I assume the new harness would be pre-loomed with the non-slit stuff (so I can justify it partially with the price of good loom). However, I can't find a part number for that piece of wiring harness.

Any ideas?

**howardc64** · 12-23-2005, 08:33 AM

I realized a method after my plug replacement that may have saved my wire loom from so much disintegration. The distintegration comes from movement of the wires. You can disconnect the wiring harness from each coil so when you pull the coil off the plugs, the wiring harness doesn't have to move much. The connector is right on the side of the coil. This may limit the disintegration of the brittle loom.

The wire looms are still brittle but I guess it will perform its intended job of keeping the wires's insulation out of direct contact with the head.

I also see a mostly disintegrated wire loom off the connector just above the power steering pump on my car. This is the exact same < 1/4 ID tubing in the coil pack wiring harness. But the wire's insulation appears to be fine.

I also found 3/8 ID split loom at your a home improvement store (Lowes here) which said "high termperature resistent" without any more info. But they didn't have anything smaller than 3/8 ID. Someone also suggested checking with a speed shop. I didn't have a chance as I had to put the car back together for next day's ETM replacement appointment :-)

200+ miles into my newly installed and likely low temp loom, they are still flexible in original condition (a quick check by only removing part of the cover near the timing belt - no need to remove turbo pipe) So I'm somewhat confident they aren't going to melt but maybe will get brittle. I'll check in a couple of thousand miles and report back.

**jdj2** · 02-02-2009, 08:34 AM

I'm about to tackle fixing the disintegrating loom on my engine harness, and have a couple of questions.

1) Does anyone know of a very high quality harness tape that could be used IPO the split loom. When I used to work in the auto industry, we used some nice fabric type high abrasion resistance stuff, but I can't seem to find a retail source.

2) Second option, does anyone know the recommended sizes/quantities of split loom required? Or perhaps someone makes a repair kit?

Thanks for any input

Jeff

**howardc64** · 02-02-2009, 09:22 AM

I used standard electrical tape and it held up perfectly fine after 30-40k miles.

If you want to replace exact loom size, you need maybe 1 foot of 1/4 inch, 3 feet of 3/8 inch, and 1 foot of 1/2 inch looms. I couldn't find 1/4 anywhere so I just used 3/8 (total 4-5 feet) of the regular stuff (not high temperature stuff)

Just FYI on how these held up in my T5 and XC70.

**Jeremy** · 02-02-2009, 07:48 PM

Replaced mine too last summer. It gets hot, but no so hot that it melts the stuff you buy at the local auto parts store. For the smaller wire bundles (and the larger ones too) you can use spiral wrap. It comes on really small diameter and does the same in protecting the wires from chafing.

Jeremy