On the 325 of 1987 (and probably many other E30 Models) the exhaust system consists mainly of two large pieces. They are joined in the middle by two flanges bolted together using three 13 mm bolts with 11 mm nuts. A gasket is sandwiched in-between the two flanges.
When I undid the flange, neither piece of exhaust system fell on my head. The front portion is attached to the exhaust manifold. The rear portion is attached to hangers at the rear muffler and another hanger, slightly more forward.
This forward hanger is attached to a metal piece that is attached to the body with a nut or a bolt.
Using a screwdriver, it’s possible to pry the forward hanger loose. The rearmost ones are more difficult. They are best pried loose after pivoting them 90 degrees, and that’s best done after loosening (using a 13 mm nut, as I recall) each end’s attachment to the rear muffler. On one side, there’s a metal attachment point. On the other side is a metal attachment point plus a strap that goes above to the muffler to the metal attachment point on the other side.
It’s easier to work on the rear hangers after you remove the heat shield that’s above the rear muffler. These are attached using four 10 mm nuts.
To re-install the rear hanger, it’s easier if you have two people helping: one to position the muffler “just so” and one to pry the hanger into position. Typically, a flat-headed screwdriver is helpful. This is far easier to do with the hanger elongated, which is accomplished by turning it through 90 degrees. After everything is in position, the hanger can be snugged up by turning it through 90 degrees again.
On the 1985 model, the heat shield plate has a more symmetrical shape than on the 1987 model. The rear hangers are also positioned differently.
It’s easy to drop the muffler and have it bend the strap attached to it, which is not the ideal situation.
At the exhaust manifold, the downpipe part of the exhaust system branches into two pipes. Each one of them attaches to the manifold with a three-stud flange. The studs are embedded in the manifold, and then six 14 mm nuts attach the downpipe.
A wire with a round plug attaches to the oxygen sensor, at the downpipe.
I sell these parts used (except for the catalytic converter that’s attached to the front portion of the exhaust). Likely prices (might vary a bit due to supply and demand, and condition) for items in generally workable condition:
- For the front part without the oxygen sensor and catalytic converter: $40
- For the rear part with the muffler: $60
- For the metal piece for the middle hanger: $5
- For the metal piece for the outboard side rear hanger : $10
- For the metal piece for the inboard side rear hanger : $15
- For the middle hanger: $5
- For the outboard side rear hanger : $5
- For the inboard side rear hanger : $5
- For the oxygen sensor: $30
- For the flange gasket: $5
- For the exhaust manifold: $20
- For heat shield above the rear muffler: $10
Probably, a set of fasteners, to replace those that were stripped or lost, might be nice. Here’s what I would most likely charge:
- For the set of six nuts that attach the downpipe to exhaust manifold: $10
- For the set of three flange nuts and bolts: $5
- For the pair of bolts that attach the hanger’s metal pieces to the rear muffler: $5
- For the set of four heat shield nuts: $5