Cutting into heat shield for rear O2s with euro headers/cats

[beta]

When I got my euro headers, they had to cut into my heat shield to connect the rear O2s behind the cats.

I'm not too happy with having a gap cut out at the top of my heat shield allowing extra heat into the transmission tunnel. So I want to get another heat shield, and this time make a much smaller cut (possibly to the side), and if possible maybe even get a nice gasket on there for the cables to go through.

So first up, I want to make sure I have the right part number. Can someone confirm it's 51487895447? RealOEM link.

Second of all, what solutions have you guys come up with? Does anyone have a gasket or something so that the cables for the O2s have something to go through and don't rub up on the edges of the heat shield? What would be the ideal spot for cutting into the shield? I think cutting a little to the side might be better than at the very top of the tunnel.

[johanness]

If u 'unfolded' your rear O2's and ran them correctly, there should be no need for any cutting of the heat shield. That said, a small hole on the side makes more sense than one on top.

[beta]

I did unfold the O2s and ran them to the cats. I guess I didn't run them correctly then, as I had them run above the heat shield so a cut was necessary in order for them to drop down.

[beta]

Hmm i'm still confused. Do you run the O2s all above the heat shield and then double back at the end? I'm unsure as to how you do it without cutting into it.

[Finnegan]

^Me too.

Does anyone have a picture, or can point to one of how to do this?

I checked Pal's thread, and it looks like a cut into the heat shield is the SOP for this install. If there's another way that's great, I just don't recall seeing it ().

[txz4]

Originally Posted by beta

I did unfold the O2s and ran them to the cats. I guess I didn't run them correctly then, as I had them run above the heat shield so a cut was necessary in order for them to drop down.

I dont remember exactly how i wired mine, but i believe i ran it on the side of the heat shield, just on the protected side, using zipties and very small drilled holes (maybe 3?) to secure it along the way. There is the small length where the cable spans the distance from outside of the shield to the cats but im not going to worry about it any more than i would any wire in the engine bay... Next time im around a lift ill snap a photo.

[22022]

This is how i did mine,I cut a small hole on the left side of the heat shield,the clips were already there.
I hope this helps.

[Finnegan]

Very helpful! Thanks for the pics--that's a big help!

[beta]

Wow that looks beautiful. Thank you very much for posting such great pictures.

txz4 if I don't have the clips like 22022 did, I'll do zip ties (or small wires) with drilled holes; good idea.

[Starscream]

I also ran mine in the same way, and that's how its ran in Euro cars,

Also be very very careful that the wires are not touching anything to do with the exhaust or are slack enough that they have the possibility too,
Esp if you are running after market stainless x pipes,
The heat under there is intense and will melt o2 wires with ease

[Ron Stygar]

[johanness]

Originally Posted by txz4

I dont remember exactly how i wired mine, but i believe i ran it on the side of the heat shield, just on the protected side, using zipties and very small drilled holes (maybe 3?) to secure it along the way. There is the small length where the cable spans the distance from outside of the shield to the cats but im not going to worry about it any more than i would any wire in the engine bay... Next time im around a lift ill snap a photo.

No pics here either (sux), but they were run on the protected side - secured much the same way. There wasn't a lot of extra length. Took us a few tries to get it right. Tony's install above looks TIDY!

[beta]

I have a followup question. Assuming I don't have the clips that 22022 has, what would be the best way of securing the cable?

I figure zip ties will eventually fail because of the heat. So I'm thinking copper wire might be the ticket. Not sure if the copper wire will heat up enough to cause problems with the lines, could always cover in silicone tubing or something. Any thoughts?

And yes I know this is overkill, but I try to build all mods for the longest lifetime possible.

[marinb]

I "unfolded" my rear O2 sensors and it still didn't reach. So I had to cut into the harness a bit (where the raw O2 wires are) just so I could get enough slack to make the connection. (the raw wires are wrapped in electrical tape in my picture).

I definitely saw the place in the heat shield where the O2 cables are suppose be routed, but there was no way in hell mine were going to reach routed like that. How do you guys with US cars make this work?

I noticed on realoem that the Euro O2 cable lengths are 1390mm and 1340mm, vs the US O2 cable lengths of 1075mm and 935mm.

[txz4]

Originally Posted by marinb

I "unfolded" my rear O2 sensors and it still didn't reach. So I had to cut into the harness a bit (where the raw O2 wires are) just so I could get enough slack to make the connection. (the raw wires are wrapped in electrical tape in my picture).

I definitely saw the place in the heat shield where the O2 cables are suppose be routed, but there was on way in hell mine were going to reach routed like that. How do you guys with US cars make this work?

I noticed on realoem, that the Euro O2 cable lengths are 1390mm and 1340mm, vs the US O2 cable lengths of 1075mm and 935mm.

Totally normal. I cut mine all the way back as far as i could reach then electrical taped the harness shut and bundled the wires together. Its a tight fit but a fit nonetheless.

[beta]

Hmmm... I guess I should pick up some heat-shrink tubing as well then. What size do you guys think will fit over the end of the O2s? I like to avoid electrical tape as much as possible.

[beta]

Here we go, coming full circle on this for documentation purposes.

The heat shield comes with the holes cut out, so no cutting should be required. I did not have the clips, but thankfully my shop had some clips in their bin of random parts.



Marinb is right, the O2s are not long enough to reach when routed correctly. You can fashion some extenders (see crfine88s thread), or you can cut into the tube a bit, then rewrap it. My shop had some beautiful cloth tape which is the factory BMW tape. You need about an additional 10cm or so.



And one final picture.

[marinb]

Did that end up being the right part number for the heatshield?

[beta]

Yep.

[RobMCoupe]

I will redo my post cat O2 when I need to replace them. My plan is start looking for Euro O2 sensors.

[beta]

I looked into it, you'll probably have to order them from europe as you can't even order the part states-side. They're about 10cm longer.

You could also build small extenders like crfine did. Might be less expensive and just as good.

[marinb]

I think they are more like 1 foot longer, according to the realoem numbers. But yeah, you're probably right that you'd need to order them from Europe.