Lotus Elan

Headlamp Vacuum System

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Lotus Service Bulletin
Class 111
Number 1973/18
Type +2S 130
Date 08.10.73
Title: Headlamp Vacuum System
Reason: To remind Dealer personnel of the fault finding diagnosis procedure.
Action:

In cases where the headlamps are elevating when the car is parked (engine 'off'), the following action is recommended. After a period, the vacuum will be overridden by the spring, and the headlamps start to lift.

  1. Check that all pipe connections are secure and NOT leaking.
  2. Using a vacuum gauge, systematically check through the entire vacuum system starting with the vacuum tank (in the chassis), the vacuum operating cylinder headlamp solenoid valve and non-return valve. The vacuum gauge should now show a reading of 15Hg.in. at all check points.
  3. If the solenoid valve and/or operating cylinder are faulty, they must be exchanged for new units. If the vacuum tank is leaking it should be repaired, either by welding on a patch (see Section 'A' in the Workshop Manual for approved welding process), or by attaching a patch with the aid of 'Araldite'.
  4. If it is suspected that the non-return valve is faulty, it may be that foreign matter in the form of flaking from either the inside surfaces of the chassis vacuum tank, or from dust and petrol vapours from the pipe bores, is holding the ball valve off its seat. The deposits can be dispersed by soaking the valve in petrol for approximately 10 minutes, then blowing dry with an air line. Alternatively, the valve can be 'purged' with petrol from the vacuum tank side (trying to lift the ball off its seat) using a force-gun or air line, bearing in mind that the valve cannot be dismantled. If, after the foregoing the valve is still faulty, then it must be exchanged for a new unit.