How to replace Heater Hoses

Whether it is ye olde folk law or something more mystical, the mention to most imp owners that you need to replace the heater hoses has owners running for the hills!

But it is not as difficult as you imagine.... though it can be a bit fiddly.


Tools Required
Sharp Knife, Screwdriver/Hose Clip Driver, Gaffer Tape, Trim Clip Tool/flat bladed tool, 7/16 and 11/16 AF spanners, general screwdrivers/tools etc.

Supplies Required
2x 5m lengths of 5/8" (16mm) bore heater hose (extra if you are going to replace the engine bay hoses), hose clips - might as well replace the engine bay hoses as well if they look like they need to be replaced, Talcum Powder, some strong nylon cord and if possible a spare pair of hands, can do the job on your own but some extra hands help!

 

1. First job when doing this is to drain the coolant from the car, the Haynes or Rootes Manuals detail this so we will not go into this here. Next major job is to remove the interior trim that goes over the rear wheel arch, (fig1) this is in order to get to the hoses. The white arrows indicate a bolt/screw to remove and the red ones show the location of trim clips. You can undo the latter with a proper trim tool or carefully spring them out with a flat bladed tool. The long trim panel is held in along its top length by the car, so to remove you need to pull it out from the bottom.
   
   Fig 1
   
    
2. After you have removed the long hardboard panel, depending if your car is original, you may or may not find a large fabric 'pillow' (fig 2) - this is part of the sound deadening system, carefully remove this trying not to tear or rip the fabric. Also if you look into the rear wing cavity you may find a number of plastic bags filled with paper pulp (these are known as crushed sheep!), also carefully remove these, there are lots of sharp edges in the cavity that can tear the bags (and you!). You may need to remove the small card trim (red arrow) You also need to remove the small bits of trim that are stuck to the bottom passenger pockets - these are just held in place with a blob of glue..
   
   Fig 2
   
    
3. Right next into the engine bay, you are going to replace them anyhow, so just cut through the heater hose where they pop into the engine bay (fig 3 and fig 4)
   
   Fig 3 and 4
   
    
4. Ok, now round the front of the car, remove the card trim in the luggage bay, hold the ends of the hose up in the air, put a cloth over the end and give them a good blow (fig 5), this will help get any trapped water out, that could end up in your sills when you get to later operations.
   
   Fig 5
   
    
5. Ok the next bit is optional, though if you are working on your own, I would recommend you do this as it will help when you are fitting the new hoses. Tape some lengths of the strong cord (about two metres) to each end of the heater hoses. Then from the engine bay push the hoses in to the holes in the car until they disappear, the grommet might come out as well but don't worry, just don't drop them into the rear wing cavity (strings helps prevent this), Then working from inside the car, pull the hose over the rear arch into the car (Fig 6 note nylon cord) and from the front, pull the hoses into the front footwell - you may need to gently pull the carpet away (if you have any!) from the front arch so you can get to the hoses.
   
   Fig 6
   
    
6. Ok after you have the rear end of the hose in the car, cut through the heater hose at the 'S' bend using a sharp knife *NOTE* when doing this on the drivers side be careful not to cut through the wiring loom! see fig 7.
   
   Fig 7
   
   
    
7. From the front, pull the hoses into the front footwell, you can use cord here as well if you want fig 8 - you may need to gently pull the carpet away (if you have any!) from the front arch so you can get to the hoses.
   
   Fig 8
   
    
8. Ok trim off the excess part of the front hose (red arrow fig 9) but leave about 60cms (2') sticking out of the sill (white arrow)
   
   Fig 9
   
    
9. Ok get a length of new Heater hose (white arrow fig 10), hold it up to the end of the old heater hose (red arrow fig 10) where it sticks out the front part of the sill. Tape together using gaffer tape. Don't start wrapping right on the join, start a little way from the join and work towards and past the join, make sure the tape is tight and smooth! fig 10. Once you have taped the join, give it a little pull, it should be secure, i.e. you should not be able to pull the hoses apart.
   
   Fig 10
   
    
10. Next step is to lightly (please note Allan!) dust the new hose with french chalk or talcum powder, Allan here bought some nice smelly baby powder, but old spice talc is ok as well! This stops the new hose sticking.
    
    Fig 11
    
    
     
11. If you have a spare pair of hands, get your helper to push/feed the taped joint in the car whilst you pull out the old hose from the 'S' bend area where you made a cut in old hose (fig 7). If you are on your own, sitting in the position shown in fig 12 makes it easier to push and pull.. you need to push the hose at one end and pull at the other or it will get stuck.
    
    Fig 12
    
     
12. TA DA the new hose will pop out of the pocket, now you can cut through the join between the old and new hose, discard the old hose, you will then be as fig 13
    
    Fig 13
    
     
13. Right with the new hose in, you by push/ pulling, be able to slide the new hose back and forth in the sill. Right this is where we had a little problem... the plan was to slide the new hose back down the sill a bit so we could feed the end of the hose though the 'S' bend, while pushing the new hose down into the sill at the front. We got the new hose through the 'S' bend but for some reason it got stuck..on what we are still not sure! So instead we pulled the end back out of the 'S' bend and then pulled the hose up into the rear pocket so there would be enough hose to get to the engine bay. We then looped the end back down into the rear pocket and through the 'S' Bend fig 14.
    
    Fig 14
    
     
14. By doing this, you can kink the hose, but with a little fiddling and twisting you can correct this.. make sure there are no kinks in hose before continuing
     
15. Ok now you will have loads if heater hose in the rear wing cavity, now if you used cord as above when removing the old hose, tape the cord to the end of the heater hose with gaffer tape so you get the cord 'inline' with the hose. i.e.. cord expanding out to the hose with tape and no steps.. If you have a helper or are not bothering with the cord, then push the hose in the cavity for about a 1 meter or so see fig 15.
    
    Fig 15
    
     
16. At this point go round or send you helper round to the engine bay, if the grommet came out when you took the old hose out, refit it now and dust it with a little talc. If you are using the cord method, by pulling the cord the hose should be pulled into the grommet when the, hold the grommet in place while you pull the hose through it. If you are not using the cord method, get you helper to put a finger through the grommet while you push the hose towards it from inside the car. You help should be able to guide the hose into and through the grommet, again hold the grommet in place while you pull the hose through it fig 16.
    
    [b]Fig 16
    
    
     
17. You need to do the same thing at the front, i.e. refit the grommets and then pass the hoses through them and you will be as figs 17 and 18.
    
    Fig 17
    
    
    Fig 18
    
     
18. Right that is it! all you need to do is to trim the ends to the right length, connect the hoses back up, refit all the trim in the car and refill the car with coolant and bleed the system. Remember it is worth replacing the engine bypass hose and the short hose between the 3 way junction and the water pump, before you refilling the system with water/antifreeze mix.
     
19. There are a couple of other ways to do the above heater hose swap, mainly going the other way i.e. from back to front rather than from front to back, and also going through the 'S' bend as part of going from back to front. I hope to have a photo how to 'extra' on this method soon.