cyclopticgaze

bmw 2002

New Exhaust — Nose to Tail

Apr 30, 2012

     I haven't taken the 02 out on the streets in a long time.  Granted, a big reason has been that it wasn't driveable, what with the rear and/or front suspension torn off (see here, here, here, and here — projects that, I'm embarrased to say, span two years).  But another reason for keeping it parked has been that the exhaust system has been in the basement and not the driveway.


     Webby's beastly banshee scream sans-exhaust certainly appeals to me, but the local po-po have proven themselves less inured to high-decibel hoonage;  they would not treat it kindly.  That's doubleplusungood when your car isn't registered or insured . . . and you've already had a few encounters with Big Brother.


     So, next project:  exhaust system!  I've been meaning to do this for two reasons.  1) There's been a niggling oil leak since I bought the car that I think is coming from one of the studs that mount the exhaust manifold to the cylinder head.  It's apparently a common problem.  Not only has it left telltale black puddles in three different states, it also drips oil close enough to the cooling fan for it to be sprayed all over the engine bay.  Then, 2) before it was removed, the muffler hung by a bent wire clothes hanger, causing it to bounce and bang all over the rear suspension during driving.  Time to remedy these things and drive.


     Those problems aside, the old exhaust wasn't in bad shape.  Stock header, downpipe, and resonator, with some aftermarket muffler that looked and sounded really good.  And since the car's got a stock motor, I don't think the stock exhaust was really restricting performance, either.  Still, those problems above were damn annoying, and if I'm gonna fix 'em, might as well do it up right.  Let's rehab the whole exhaust.


The muffler and center resonator were pulled off a long time ago, so the teardown just means pulling the manifold and downpipe off the car.  Gotta get the ignition wires out of the way first.  I labeled the wires so I won't have to do any thinking later when I re-install them.  With those out of the way, there's a metal heat shield to remove to gain access to the exhaust manifold.

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Heat shield gone, the exhaust manifold appears stock and original.  Each of the four outlet pipes has two bolts to remove, an upper and a lower.

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     Pulling those eight bolts wasn't hard, it was just a pain in the ass.  I got lucky in that the bolts were the proper Copper crush type (we'll see new ones later).  That meant they were soft and not rusted, so they unscrewed without drama.  However, the problem is access.  You'll cramp your wrist getting to the bottom ones — a stubby box wrench is highly recommended.  It's slow going when you finally manage to get a bite on that bolt you can't see, only to get like 30 degrees of unscrewing done before having to start again.


The lower bolt on port four actually took its mounting stud with it, which I understand to be common.  The manifold + downpipe didn't want to come up out of the engine bay, so I jacked up the front end a little and dropped them out the bottom.  All of the manifold gaskets came off easily, without scraping.  I think they may have been replaced before.

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You don't want to re-use these studs, so out they come.  Here, I'm using the trusty double bolt technique for removal.  They all came out easily with a little penetrating oil, and without the need for heat.

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Covered with oil on the inside.  That's normal for the top studs.

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All the parts are off the car, so now onto the rebuild.  I feel kinda bad;  the old exaust really wasn't in bad shape.  Anyway, on the right:  old and busted.  Left:  new hotness.  Header from Ireland Engineering, with a coupler to join it to a new Ansa center resonator.  New metal heat shield gasket from a 320i and all new hardware.  New Ansa muffler.  The muffler is perhaps the most superfluous purchase;  that old one is really quite nice and could serve for many more years.  I'll probably sell it.

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     Anywy, to the reassembly!  In go the new header studs.  I got replacement studs from BavAuto.  They seem fine, a little shorter than the ones they replace, but shouldn't be a problem.  These new ones are threaded all along their length;  they don't have a break in the threads to denote which end goes into the head and how far, like the original ones have (pictured above).  Just gotta make sure that the top studs don't get threaded too far in — they poke into the head and you don't want clearance issues.  I cleaned the oil out of the holes as best I could and hand-threaded the studs.  I held a ruler against the head to measure how far they'd gone in, using the old studs to compare distance.  A key point is to use Loctite on the threads.  This will ensure the top studs don't leak oil and it will lock the studs in place so you can actually screw on the bolts that hold the exhaust header in place — without Loctite-d threads, the studs might spin as you attempt to tighten the Copper nuts.  I used Loctite Red, although I've read different opinions on which Loctite to use, Red or Blue.


All eight new exhaust header studs in place.  Now it's an overnight wait to allow the Loctite Red to fully set.

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Before the Loctite set, I quickly popped off the valve cover to check that I hadn't threaded the top four studs too far into the head.  Nope.  Here, you can see the stud threaded into the head, and it's not poking into the valvetrain.

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Waiting for the Loctite to set, I went ahead and hung the new header.  This is Ireland Engineering's 4-into-1 "street and track performance" step-header.  Overkill for my stock engine, I bought it a while ago on a whim (think I used my tax refund).  It negates the need for the downpipe, but requires an adapter (which Ireland also sells) to fit it to the resonator.  They offer the same with a ceramic coating, but I didn't feel the need to spring for that.  With a lot of banging and clanking and twisting, it went in from above.  Once it was in the engine bay, I put the new heat shield exhaust gasket onto the header studs and then hung the header onto the studs.  The new gasket will get bent downwards over the header to shield the spark plug wires from the high temperatures of the exhaust manifold.

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Next day, after the Loctite has set, on go new Copper bolts.  One end of these is flattened like a washer and goes up against the header, the other end has been slightly crushed, which I presume gives it some bite on the stud threads.  I suppose that's needed because you're supposed to coat the threads with LM 508 anti-seize compound.  That's a temperature-resistant, Copper-based compound that prevents the studs from rusting and protects against corrosion from disparate metals touching;  it'll help you get the header back off someday.  The anti-seize lubed the threads well and apparently the Loctite did its job because the Copper nuts went on fine.

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     File under:  Things They Don't Tell You.  Tube #1 on this header has a fairly tight bend in it.  So tight, in fact, that you can't thread its lower Copper nut if the header is bolted against the cylinder head like above.  What you gotta do is get all eight Copper nuts started on the stud threads while the header is just kinda floating, then you can tighten them all down and push the header flush against the head.  Lesson learned after I tightened all four upper nuts, only to find myself unable to start the lower nut on tube #1.  I had to slacken all the upper nuts and pull the header away to get that bottom one started.  Then I could tighten all eight Copper nuts.


With the new header bolted up tight, I bent down the heat shield gasket and went about reattaching the spark plug wires.  I found these nifty wire covers a while ago.  They're woven fiberglass and pretty cheap.  Anyway, they withstand some pretty extreme temperatures, and between them and the shielding gasket, I figure my spark plug wires are fairly safe against this new header's heat throw.

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     I fired up the engine to see if that old oil leak was still around.  Yep.  Seems to be coming from the front of the engine.  Pretty minor, but future project, I guess.


     The new header smoked pretty bad, and it was an unfamiliar odor.  The smoke is coming off of the entire header, so it must be the black paint that Ireland used.  Smells terrible (like, "I can feel the cancer" terrible), but it's been getting better as I run the engine.  The paint's been flaking off, too, so I figure they either didn't use high-temp spray paint or didn't prep the metal tubes for paint.  If that type of thing matters to you, you should probably spring for the ceramic coating option on Ireland Engineering's headers.  Or do like I do and don't give a shit because that new header is still shinier than the rest of the car.


     Time to do some plumbing under the car, so up it goes on the ghetto lift — four jack stands.  My driveway's slight incline makes it a bit of a chore.  Whenever I'm done with this, I always grab the car and give it some really hefty pushes from all around.  It'll settle the weight and let you see where it's sitting heavy and lightly.  Adjust as needed.  Builds confidence, too.


Catchin' air.

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This is the stainless steel coupler that Ireland sells that matches their header to a stock-sized center resonator.

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Problem!  The center resonator has this bend in it (just like the stock exhaust) so that the pipe can clear the rear sway-bar and rear suspension.  Here, my fancy new exhaust is having clearance issues with my rear suspension and is hitting my fancy new swaybar.  I haven't done it yet, but I'll probably just find something decently heat-tolerant to put between the pipe and the swaybar, maybe just a bunch of layers of high-temp header tape.  I'll get in to what's causing this problem below.

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As one would hope, the Ansa muffler bolted onto to the Ansa center resonator without drama.  The muffler has two rubber hangers that hang it from the body.  Here, you can see that the front rubber hanger is tilted toward the rear of the car.  This is in-line with the above image where the exhaust isn't clearing the suspension correctly.

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The muffler's rear rubber hanger is also tilted rear-ward, but not as badly as the fore hanger.  Despite being off-kilter, both rubber hangers went on fairly easily.

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With regards to the fitment issues, I think this is the problem.  Either this coupler is about half an inch too long or the header is a little too long.  I banged on the coupler really good with a rubber mallet, so it's on the header as tight as it can go.  And I know my engine isn't displaced because I already fixed that (if anything, the engine is still too far forward).  The curse of the aftermarket:  go-fast goodies are great, but their build tolerances may not be up to stock snuff.

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The back end still looks hot.  I've never been a fan of the off-center stock exhaust tip.  (As an aside, I hatehatehate a center exhaust when there's only a single exhaust tip.  It just looks like an asshole to me.  Case in point:  Porsche Boxster.)

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     So, how does she sound?  Well, firstly, the loud clanking is gone.  I attribute that to getting rid of the bent wire muffler hanger;  the exhaust isn't bouncing off the rear suspension anymore.  I'd say it sounds throaty and loud, but not obnoxiously so.  This is no fart-can ricer setup — you won't get pulled over for noise.  But you will turn heads.  If you do long highway drives, consider a stock setup.  If you want a sporty sound but don't want to break any windows, I highly recommend this setup.


     By the way, now that I can actually drive the heap again, I've found that Webby handles like a go-cart!  All of that suspension work has payed off big time.  Huge fun.