1906 Rover

A guide to 6HP Rover cars


Archive for February, 2011

A method of cleaning petrol tanks and carburettors without using nasty chemicals.

Friday, February 11th, 2011

On a number of occasions I have come across the problem of removing a tacky (or sometimes hard) brown varnish.  This residue is left when vehicles or equipment have stood unused for some years and the petrol has slowly evaporated.  I have tried a number of chemicals in attempts to remove the residue, but with little success.  I finally found that a basic non-biological liquid detergent (for washing clothes) plus hot water does the job well.



  • Strip the carburettor, removing any gaskets and the float.  (If a float has had any damage and has got petrol inside then putting it into hot water will cause the petrol to evaporate rapidly, blowing the float apart.  Experience is a wonderful thing!)
  • Place the carburettor in a saucepan and cover it with a solution of water and detergent.
  • Bring this nearly to boiling point and leave it to stand for an hour.
  • Rinse the carburettor in clean water, using a small brush (such as an old toothbrush) to remove the residue. The residue should come off easily.
  • Use an airline to blow any residue out of all drillings.  If a jet was stuck it should now come out without damage.
  • If necessary repeat the process, soaking the carburettor again and rinsing off any remaining residue.



  • Fill the tank with a very hot solution of water and detergent.
  • Leave to stand for 12 hours.
  • Rinse well and allow to dry completely (this is very important).
  • The residue should turn whitish and go powdery so most can be blown out using an air line.  If the tank has baffles and inaccessible places it will not be possible to blow out all the particles of residue, but these are normally heavy enough to settle out in filter units and should not cause any problems.