How to replace the heater hoses
(the ones through the sills)

by Peter Nunney

Impressions Apr./May 1996

None of the Imp books, manuals or handbooks tells you how to replace the heater hoses. Yet one of the service items is: "Check condition of heater hoses and renew any doubtful looking ones, before they start to give trouble. They usually persih at the engine end, through heat, movement or just old age."
A lot of folks just chop off a bit and join on a new piece, but it's a bodge... and who says it's still alright in the sill, where you can't see it ??
If you don't know where to begin, here's how to go about replacing the hose the proper way:

  1. Drain cooling system at radiator
  2. Disconnect heater hose from engine / 3 way valve
  3. Remove luggage compartment trim in front and disconnect hose from heater unit
  4. Because it is impossible to drain the hose between the wheel arches, it is needed to plug each end with a wine bottle cork to prevent the remaining pint of coolant emptying into the sill when the hose is drwan through
  5. Next, having plugged both ends with a cork, pull the hose through the front bulkhead from the luggage compartment into the passenger compartment - leave it up against the front wheel arch
  6. From inside at the back, remove rear side interior trim panel, seat belt fixing etc., to allow access into rear wing area, and pull the hose through from engine compartment
  7. Remove (hardboard) bottom of rear glove box - just pull out. You can see where the hose does a sharp S-bend where it enters the sill - the metal edges here are very sharp !
  8. From this S-bend pull the engine end of the hose through and up into the glove box
    Now you have two free ends of hose, with its centre section still in the sill
  9. Using some strong string (long enough to pass right through the sill), tape one end to the front end of the hose, with masking tape wound round as smoothly as possible: don't clip or knot it, as this tends to to jam the hose in the sill
  10. Pull hose through from rear glove pocket, feeding the string through the sill with the front end of the hose as it goes, until the hose emerges from the glove pocket
    The only thing you have now left that goes through the sill is a piece of string
  11. Tape the string to the new hose and pull it through from the rear to the front (reverse of removal) - it should come easily. Don't pull too hard on the string if it gets stuck: it could be cutting the hose on a sharp piece of metal. If it does get stuck, pull it back and try again
  12. From here on it's the reverse of dismantling. Make sure you don't get any kinks in the hose, especially at the S-bend
If your car has been rustproofed with Ziebart or similar goo injected into the sills, the old hose may be stuck fast initially. You can unstick it by twisting the old hose that goes through the sill around ans around until it frees.

You should be able to replace both sides in two hours.