Hi

2.0 D Xtype, I’m 99% sure my heat issue is a blocked core and I need some hive mind assistance as to which are the hoses you need to access in order to do the flushing of the heater core? I know there’s so many threads on this but none I’ve found actually show which hoses to use to do this.
can anyone describe or show me which hoses to use? Thank you

 

Mossman, what Iam finding in service manual is vague at best, but also knowing the car, I think I can help guide you to where you need to go. First things first, you are going to need to get the front end of the car up in the air so you can crawl under it. From there, you will need to crawl under the car at the firewall and slide around to the center of the car. If you look up at that point, you should see a plate with 3 hoses (yes 3, not 2) coming off of it. 2 are going to be on top, 1 hose on the bottom. It is not going to be too far up from where the firewall goes from under the car to going up the back of the engine bay. The lower hose is your drain for any condensation that builds up in the ventilation system. The top 2 hoses are those for the actual heater core. Ensure the coolant system is trained (still going ot have some coolant in these lines because they are a low point). From there you should see some clips holding the lines on to the plate and you simply need to remove the clips and pull the hoses off.

With this being said, I would follow the top 2 hoses up to see if there may be an easier point to remove them that is more on the top side of the engine. This is going to make working on this problem a bit easier. Option 2 would be to get say 2 meters (maybe 3) of the same size heater hose and run them up along the wire wall to where you can easily get to them. You can then use the clips to secure them to the heater core.

I would first try simply using a little bit of low pressure air on each hose to see if you can free the plug. It may come out pretty easy. From there, I would say you need to switch tactics and use what is called a "water hammer". In short, you are going to take a small amount of water, put it in the hose and then using some air, blast it into the heater core. The moving water is going to "hammer" on the blockage and potentially break it free. If you can figure out which side is the discharge, then I would spend most of my time applying air on that side to help push the plug back out the inlet where it came from. Trying to push it through the heater core could prove to be difficult. You may even get lucky and find the plug right where the hose connects. You wlil know the heater core is unplugged as you will most likely squirt a bunch of coolant out as the plug is dislodged. Each time you switch tubes to start hammering the other way, add a little bit of water (few mls, 5 or so).

 

Mossman, what Thermo said. First try to clear the plug, if the heater hoses are in good condition.
If not succesful, and/or the lines look brittle, it might be easier to disconnect the hoses from coolant lines in the engine bay, dismantle the heater box assembly under the dash, and remove the heater core and hoses from the cabin side.
New hoses can be found eg. SNG Barrat's site.
Having done the heater hose change once on my 2003 2,5 AWD, I found that there is no way to reach the hose clips on the heater core from the engine bay. Now, I don't know about the diesel variant, and how much space there is between the diesel engine and firewall, but at least on 2,5L engine, hose clips cannot be accessed from underneath the car, or the top, since the flange that the heater core piping attaches to the firewall, is located in a little 'caveat' in the firewall.
You'd have to remove top of the engine on the firewall side, to gain access.

So, what I did, I removed the upper intake manifold and right hand seat for access, and removed center console. Then I removed the heater box retaining screws, four of them, if I remember correctly, there is threads on this forum about how to dismantle the blower/heater housing. The heater box underside is removable, it's like a lid underneath the assembly, and it houses the heater core. But it has two or three plastic clips, that you must bend to be able to remove the cover.. these will likely break, but that's no big deal. After removing the housing you can remove it, and have the core out for cleaning.
Re-assembly if fairly easy, and hoses can be fed easily to engine bay from the cabin side, extra pair of hand helps at this point, though.. those broken clips can be replaced by small zipties.

I should note, that if replacing heater hoses, be sure to get the correct ones. On 2,5L they need to have correct moulding an curves in the right places, to bypass cat and exhaust, so no aftermarket straight automotive rubber hoses just bent to point upwards on this task...
Good luck