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Faults, Fixes and DIY Please share your experience and knowledge with other members by contributing your own DIY, or by helping another member find the elusive fix!

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Old Wed, Jun-07-2006, 03:54:23 AM   #1
Flash Sideways
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Default E46 M3 euro header and cats install

Get a drink - this is a long read but I hope it answers most questions.

Tools needed:

a good quality, basic set of 1/4, 3/8, and 1/2 inch sockets, including short and deep well sockets and machined ratchets such as Craftsman, Facom, or even Husky. I did the install with a $50 Husky set from Home Depot and another $10 in swivels

drop lights

floor jack and jackstands

high quality blue nitrile gloves

someone to keep you company and hand you things

Parts needed:

euro headers P/N 11627830658 cylinder 1-3, P/N 11627830660 cylinders 4-6. Approximately $1800/pr. These headers were used until March 2005.

The later headers are P/N 11627833500 and 11627833643, over $2000/pr

Strangely, the CSL has the same forward (1-3) header, but a different rear header (4-6): P/N 11627833501. I'm wondering if the headpipes after the header flange are different as well, which may cause a problem installing the CSL headers on US headpipes. :nixweiss:

euro cats: P/N 18307833673, about $2300

6 exhaust manifold gaskets, P/N 11627830667, approximately $6 each

18 extra header nuts, P/N 11721437202, 35 cents each. I lost one during the last install, so they're good to have around.

Depending on how old your car is, you will most likely be able to reuse the cat gaskets which join the cat section to the rear resonator section. I've reused mine numerous times without problems, but if you want to be thorough, get two for this install: P/N 18307830674 $7 each.

As best I can recall from memory, the steps are as follows:

1. remove strut brace

2. remove coolant overflow tank. This requires pulling a single bolt out of the right fender. You will need to pull the hose off the bottom as well.

3. remove overflow hose from the coolant return pipe. This will spill coolant all over your heat shields unless you do two things - have a catch can ready, like a Planter's Nuts can - and cut the finger off a blue nitrile work glove to seal off the coolant return pipe. Stupid, but it works well.

4. remove EGR valve from the side of the block. It sits just above the top heat shield, in its own little cutout.

5. unbolt heat shields. Its two aluminum plates sitting one atop the other. Three cheap slot nuts are all that secure them to the body, and 5 bolts attach them to the block.

6. remove the 6 nuts holding the head cover to the head. take off the oil filler cap, pull the head cover, then put the filler cap back into the head to prevent crap from falling into that sacred valvetrain.

7. Look at all the wires under the cam cover!! Run! Run Forrest!


Those are your O2 and EGT wires. They're loomed nicely under that plastic retainer. You'll pull that off later and take the wires out from under it in order to get extra length so you don't have to cut and splice your O2 sensor wires.
I have to do a bit more research, but I think there are two O2 sensors in the BMW catalog that you can use instead of the stock rear sensors, and they will give you more length than you need.

If you go the genuine euro route, spend the extra $6 and get the two wire guides made specifically for keeping the sensor wires off the pipes: P/N's 11787831183 and 11787831182

Until you are ready to pull the headers, thats it for the top of the motor for now.

8. jack up the front of the car and put your stands in place.

9. pull all the bolts holding the giant thrust plate to the bottom of the chassis. Two plastic shields next to the thrust plate also have to come out. You'll know which ones I'm talking about when you get under there. (caveat: if you jack the car up unevenly and pull the big thrust plate off, there is a chance that you will harm the alignment. You'll have to get the car realigned then. If you can take the plate off when the car is on the ground, and replace it the same way, you'll have the best chance of keeping a straight alignment. )

10. pull the bolts holding the forward exhaust section (aka Section 1 or "S" pipe) to the US headers and the rear resonator section (aka Section 2 or "X" pipe).

11. drop the forward section and pack it away. Its best to store it upended so all the moisture drains out of it.

Take a look at the US headers. you have a sausage shaped cat in each collector, with precat and postcat O2 sensors in each, 4 total. Take some masking tape and label each sensor so you remember which goes where. My system is to call them by their bank number plus a position letter. Therefore, you'd have "123F", "123R", "456F", "456R". The 456 header also has the EGT sensor in it.

Be careful with all the sensors. Don't drop them or bang them into anything. Get your numbering system worked out right, because if you reverse the O2 sensors, you'll burn them out.

Now it gets funky...

12. You'll have to pull the header nuts off. They are copper nuts with a dent in them for retention against motor vibration. Make sure you have a nice selection of 1/4 inch drives and sockets, plus a couple of different universal swivels, some short extensions, etc. Depending on how tired and frustrated you are by now, you may think the car is changing the requirements for each single nut. I was up the entire night before, racing with my friends, and by the time I got to this point I was nearly psychotic.

13. with all the nuts out, crawl under the car and see if you can jockey the headers enough to gain access to the O2 sensors. If you can, then take an open end wrench and try to get them out. If that fails, you'll have to pull their connectors apart in the above mentioned plastic bracket. Same goes for the EGT wires. Number the connectors you pull apart so you know who attaches to who.

14. drop the headers. Marvel at their ugliness compared to the beautiful, traditional euro headers. Curse the EPA for their ridiculous cold start emissions reuirements. How many times a day is your car cold anyway?

15. gently clean the exhaust ports on the head to remove any adhered gasket material. Its probably not necessary since the BMW gaskets are really high quality, but just give it a look to be sure.

Installation is, as they say, "the reverse of the removal". Its a lot easier though because without the US cat-in-collector headers, you'll have a lot more room to work next to the block.

About the only thing that will be different as you reassemble the car is the change in the sensor wiring. You'll have to pull all of the rear O2 wires out of the loom on top of the head and run them down behind the motor, along the transmission, and into the post cat sensor bungs. You'll also need to pull the EGT sensor down there as well. If you use longer sensor wires, order and install the wire looms I mentioned earlier. If you stay with the stock US wires then they should be taut enough to stay in place and not contact the exhaust anywhere, but it doesn't hurt to put some heat-resistant tape or jackets in any area that looks like it could be a contact problem.

So put the car together and enjoy it. It'll take about a tank of gas through the motor before your ECU learns the new parts. If you can get your software flashed for euro headers and cats, you'll see even better gains.
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Old Wed, Jun-07-2006, 04:45:51 AM   #2
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any pics to go w/ the writeup?
2002 Topaz/Black M3-Slicktop-SMG: OEM CSL Bootlid, Mini-CSL Battery, TMS Pulleys, Stoptech SS Lines, Borla muffler & Midpipe, Hotchkis Sways, Eibach Springs, RE RSMs, PowerFlex Rtabs, PowerFlex Subframe Bushings, TMS Subframe Reinforcement, Blk Grills, Blk Side Gills, VCSL Center Console, Euro Front Bumper, Hamann Fog Ducts, ACS Lower Lip Spoiler, FUCY Rear Diffuser, LED Tail upgrade w/ outer ring mod, D/A street software, RPI Scoops, e92 m3 18" rims w/ PS2s
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Old Wed, Jun-07-2006, 05:32:25 AM   #3
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Chuck, thanks for the writeup. Just what I've been searching for.

My CSL headers are part #500 and #501. I hope these will work.

Last edited by gixxer_kidd; Wed, Jun-07-2006 at 05:41:43 AM.
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Old Wed, Jun-07-2006, 05:44:50 AM   #4
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excellent write up did you also take pics during the install?
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Old Mon, Jun-26-2006, 07:48:22 PM   #5
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Old Sun, Dec-24-2006, 09:53:16 AM   #6
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Question Header Install

Very nice write-up! Are there any others out there that have picts of an E46M header install? :nixweiss:
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Old Sun, Dec-24-2006, 02:59:55 PM   #7
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You could take the pics... if you buy my Evosport headers!
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Old Thu, Dec-28-2006, 11:30:22 AM   #8
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Did you use new bolts for the thrust plate? I believe the manual called for new bolts?
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Old Tue, Jul-01-2008, 03:41:22 AM   #9
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Old Wed, Jul-16-2008, 08:52:45 PM   #10
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Originally Posted by ninekrpm View Post
why.. its so old.. haha..
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Discussing E46 M3 euro header and cats install in the Faults, Fixes and DIY Forum - Please share your experience and knowledge with other members by contributing your own DIY, or by helping another member find the elusive fix! at BMW M3 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)