Manual - Chapter 5 - Fuel & Oil

22: Exhaust system: removal and refitting

  1. Working evenly on each exhaust pipe in turn, remove the exhaust pipe/cylinder head retaining nuts, then support the front end of the system while the nuts or bolts retaining the silencer to the footrest plate are removed. Withdraw the system and prise out the old gaskets from the exhaust ports; these should be renewed whenever they are disturbed.
  2. On refitting, fit the new gaskets to the exhaust ports and stick them in place with grease. Carefully clean the threads of all mounting studs, nuts and bolts and apply a high-temperature copper-based anti-seize compound such as Copaslip or Never Seeze to the threads to prevent corrosion. Check that all components are cleaned and in place, particularly the exhaust pipe retainer plates.
  3. Fit the system loosely to its rear mountings, then manoeuvre the exhaust pipes into their ports, position the retaining plates and secure them with the nuts. Tighten the nuts evenly and progressively to the specified torque wrench setting, then tighten the rear mountings securely.
  4. The system can be divided into its component parts by slackening the clamp screws or bolts. Note that any component found to be stuck with corrosion should be cleaned carefully and treated with a coat of anti-seize compound on reassembly. The clamps have locating lugs which must be engaged correctly in their recesses on refitting so that the clamps do not foul each other or chafe against any other component.
  5. Check carefully all mounting components and renew any that appear damaged or worn. Note that the silencer mountings were modified on 100 models for 1986 on, the simpler mounting used on the 75 models being introduced.
  6. Being made of stainless steel the exhaust system should last a considerable length of time. Clean it regularly and inspect it tor any signs of damage and seek expert advice if signs of corrosion or deterioration do appear. An authorised BMW dealer may be able to supply suitable cleaning materials and polishes, or recommend suitable products.
  7. The silencer cover panel is retained by five screws and washers which are fitted into separate nuts set in brackets on the silencer, with a cap nut securing a rubber mounting at the front on 100 models. The nut holder on 100 models, into which the rubber mounting is screwed, can break away as a result of temperature-imposed stresses. If this happens, the silencer must be removed and taken to an expert with facilities for welding stainless steel.
  8. A new rubber mounting has been introduced to prevent this from happening. Note that the mounting outer end hexagon should be held with an open-ended spanner, to prevent it from shearing. whenever the cap nut is tightened or slackened, and that the cover panel should not touch the silencer at any point other than its mountings.

22.2 Always renew all exhaust gaskets whenever they are disturbed

22.3a Assemble system on to its mountings - secure front mountings first ...

22.3b ... followed by rear mountings

22.4 Check clamps are correctly positioned and securely fastened