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View Full Version : Exhaust setup... word of advice.


Hohner
07-06-2004, 06:56 PM
Well, I wanted access to my transmission because I might possibly be getting a new clutch, so I removed the entire exhaust system. In the process I broke 3 bolts out of the four coming off of the headers to the exhaust. I'm still at a loss on how to repair these bolts, because when I put the exhaust back on, it won't stay put. I ran the car w/o any exhaust setup, straight from the headers. My advice, don't do it. It's annoyingly loud and you'll sound like a dork. I thought it was bad having a freeflowing muffler, but this tops it. Think of removing your muffler. Running from the headers is about 5x as loud. It's awful. Performance wise, I don't think you'd gain anything because of the massive loss of backpressure, I didn't want to see if I was any faster because of the neighbors! Ahh! So, yeah, my question is: how do I rebolt the exhaust since the bolts are broken?

Jordan
07-06-2004, 09:25 PM
Those arent bolts. They are studs.

You can unscrew the studs and thread new ones in.

Note that is much easier said then done.

Don't drive around too long with open manifolds, you will ruin your exhuast valves.

FYI m20's running open manifolds are SLOW, without the backpressure they run and pull like poop.

BimmerKris
07-06-2004, 09:58 PM
before i finished my exhaust, it was strait off the down pipes into a hollowed out flow master with nothing connected to it. it was fun at first, but became a huge annoyance real faston the highway i couldn't even hear the radio at full blast.

Hohner
07-06-2004, 10:15 PM
Originally posted by Jordan
Those arent bolts. They are studs.

You can unscrew the studs and thread new ones in.

Note that is much easier said then done.

Don't drive around too long with open manifolds, you will ruin your exhuast valves.

FYI m20's running open manifolds are SLOW, without the backpressure they run and pull like poop.


Alright, thanks Jordan. Where can I find 3 new studs? I noticed on the top side of the flange, the studs are welded with two small tack welds. Part of the stud is still inside, so I don't know how to get it out.

Exhaust valves, how quick can the damage be done?

And, yes, I bet m20's are slow, i'm running an m42 in my car, so, are you positive that it's studs not bolts? (Yes, right now I run and pull like poop. It's true.)

Quack
07-06-2004, 10:42 PM
you are talking about the bolts on the headers right? not the ones on the cylinder head right?, if you are you can just drill out the old ones & replace them with a nut & bolt

Jordan
07-06-2004, 10:54 PM
They aren't welded on mine.....

It would be alot easier either way to pick up a pair of used exhuast manifolds. They arent worth anything...

Quack
07-06-2004, 10:58 PM
^^^ agree, but why not spend a little more and get real headers

Hohner
07-06-2004, 11:04 PM
Tell me, what is the difference between exhaust manifold and headers. I've been told i've got both, I don't know what to correctly label where my exhaust exits the engine.

BimmerKris
07-06-2004, 11:19 PM
headers are round tubes, for the 325's should be 3,2,1 style, with a different pasth for the exhuast to take and keep it a cooler temp


they look like these or varation of them

Axxe
07-07-2004, 12:14 AM
Do you have access to an acetylene torch? If you do, just heat the crap out of the manifold right around where the stud threads in, then use a vise-grip to twist it off. This is the easy way to do it. If that fails the exhaust manifold needs to get taken off, the studs carefully cut off, holes drilled that are the proper diameter and then they need to be tapped (pain in the ass on cast iron). Basically if they don't come off it would be easier to buy a new manifold and install it along with new gaskets. Exhaust is the most pain in the ass component to remove because of all the heat cycles it goes through.

Hohner
07-07-2004, 12:20 AM
Well, with that, I've got headers... must've come from the factory like that. I've got an uncle thats a welder, says I should stuff a metal rod inside the hole where the bolt is, pound it out, and dremol off the tack welds. Then, I can stick a bolt, and use to nuts to tighten the gasket and tubes together.

BimmerKris
07-07-2004, 06:51 PM
if you got headers then they should all be one peice down almost to the cat converter. the bolds that you are talking about are attatching the manifolds, to the down pipes. i don't think bmw ever put headers on a stock car, it wouldn't pass emissions.

ara325
07-10-2004, 05:30 PM
I agree with BimmerKris. I don't think they'd come from the factory with headers...it'd be nice though!

Hohner
07-15-2004, 04:52 AM
I'm not talking about the bolts that go from the engine to the tubes, i'm talking about the bolts that go from the bottom of the tubes (downpipe?) to the cat converter.