Exhaust Notes

Many Messerschmitt owners will have experienced the alarming increase in exhaust noise that is evident when the nut comes loose. It is extremely difficult to tighten with the engine in place and often the only resort is to tighten it with a screwdriver and hammer. Invariably, this damages the nut. Most service work on the Messerschmitt Sachs engine should be carried out with the engine out of the car. Reference to the service manual shows that Dynastart brushes require regular inspection.

While the engine is out, it is a good idea to take the cylinder off to inspect the piston rings, transfer ports and exhaust port. Removal of the exhaust nut normally needs some kind of special tool and the original ‘c’ spanner is the ideal way to get a good grip on the nut. Other methods include a chain wrench as used by pipe fitters and the last resort, a hammer and screwdriver or chisel. The nut is always damaged by the last method and it should be used only in an emergency.

If you are fitting a new silencer, or have dismantled the silencer from the front pipe, the correct procedure is as follows:-

1. While the cylinder is off, carefully clean the exhaust threads with a wire brush. Be sure to remove all debris from the threads. Do the same with the exhaust nut using a sharp spike such as a toothpick to clean out all debris. Lightly coat the exhaust thread with copper-based anti-seize lubricant and do the same to the nut. This will ensure that the nut can be fully tightened and will be easily removed at the next service inspection.

2. Fit the front pipe to the cylinder with a new exhaust gasket in place. Tighten it to the point where the front pipe can still be moved while the pipe is aligned to the silencer.

3. Smear exhaust joint compound both on the pipe and the internal bore of the silencer. Note that this compound hardens within a few minutes so the silencer assembly must completed quickly.

4. Fit the mounting studs to the silencer brackets and tighten the nuts.

5. Fully tighten the exhaust nut.

6. Fit a ‘u’ bolt clamp to the exhaust to silencer joint and tighten fully.

7. Finally, fit the exhaust nut-locking device as shown in the photograph. This is a 42mm ‘u’ bolt clamp. The picture shows a factory original exhaust nut. MOC supplies a much stronger nut with machined slots for the ‘c’ spanner. Bend one leg of the clamp to make contact with the exhaust nut as shown. Fully tighten the clamp.

I have never had a nut come loose using this method. The ‘u’ bolt clamps, copper based anti-seize lubricant, and exhaust joint compound are available from Halfords and many car accessory shops in the U.K. or your local auto parts shop in the U.S.A.