98 300tdi heater core replacement

[Erik BM]

Hi All,
Just out of idle curiosity and in case there is a time warp and I can go back 24 hrs, before I wrecked the 'tube out fittings' on my new heater core, trying to get the blasted things to align with the pipes going up under the dash...:confused:

How are you supposed to loosen the pipes under the dash, or the heater core, enough to align them easily and then clamp them? Both are incredibly tight and didn't give me enough room to slot them together without trying a gentle persuader, which of course buggered up the ends of the pipes. :mad:

I have the entire dash off (as despite advice to the contrary, you can't slide the heater core out with it on), but the bracket that holds the pipes on, under the dash, appears to be held by screws from the firewall side, which don't actually appear, on the firewall (must be a second panel there???).

I am now resigned to grinding the ends of both the core and the pipes and seeing if I can get a heater hose to clamp tight on both of them.

Any other ideas? If you can tell me what I should have done, then that would be helpful to others too.

Regards, Erik

[Erik BM]

I slept on the problem and this morning I had one last go at it. I ground off the flange on the worst joint and put a heater hose over it and clamped it on, then I cut off both pipe ends, running from the engine bay. Then I put the other joint in place on the workbench and while holding together with some firm pressure, tightened the compression fitting on and it held OK (btw - the rubber o-ring is supposed to sit down in the gap/joint, not up at all). Then I slid the heater core back in as far as it would go (not quite far enough, but it will have to do). I cut the radiator hose to suit and put it onto the now shortened pipe and cut another short section for the other pipe.

Not pretty, but it works. If it fails, then I can always go and buy another core ($190ish) and some new pipes.

I still don't understand why the heater core was wedged firm, when it was in place, so that I couldn't disconnect the joints easily. I also don't understand why the new one wouldn't go all the way back in - but I am now beyond caring, 12 plus hours later.

Erik

[p38arover]

I have the entire dash off (as despite advice to the contrary, you can't slide the heater core out with it on), .....

You can, actually. I did mine in about 2 hours using the instructions on this site http://www.aulro.com/afvb/technical-chatter/40034-heater-core-1997-disco-diy-workshop-5.html


......but the bracket that holds the pipes on, under the dash, appears to be held by screws from the firewall side, which don't actually appear, on the firewall (must be a second panel there???).


Very true. What idiot in Valeo designed that? My tubes had been cut off by someone so I had to replace them.

If the screw had been put on the other side it would have been simple. I drilled out the screw from under the dash and then brazed a nut onto the shaped clamp plate. Then I could insert a screw from the cabin side to tighten it all up.

Whoever had previously tried to replace the heater core had stuffed the outlet fittings then given up. The core I took out of the car was not the original. It was made some years later (it was date stamped).

[Erik BM]

Hi Ron,
I didn't manage to find that thread when I searched for heater cores, so I never tried pulling the bottom of the dash back and out of the way. I guess it would work, except that there is no way that my pipes would have come off like that one did. Mine must have been clamped by a novice zealot, as they were so unmoveable that I couldn't get them out. Maybe now that they have been levered on half a dozen times, they might just be ok, but it is too late now. I have castrated them already.:twisted:

Erik