And it is :)
Didn't realise you'd put that here... but your diagnosis was spot on and very much appreciated. She's very happy now and I hope to see a slight improvement in economy. It's also very nice to start up on six cylinders instead of limping around on 5 trying not to cause too many vibes until the LPG kicked in on 6.
Hah, old cars. Love em!

C'mon lads, can we get this thread back on topic? Have you managed to bodge your pipes and get the AC working again?

You know that's not going to happen until Autumn. It's the law....

Hehe,.... No! I've had multiple attempts, spent loads on brazing rods, gradually cut the inny/outy pipe back when attempts have failed. Given up on trying to repair the pipe having made things worse and having to cut the pipe back, been trying to simply seal it on the last couple of attempts which would at least allow front AC to work. Bought some more brazing rods today but only because I was passing Machine Mart, while I was in there I was tempted to buy aluminium mig welding wire instead of brazing rods for my next attempt but still went with brazing rods because I can't see 0.8mm welding wire being easy to weld aluminium pipe that's only around the same wall thickness. I think the eventual cure will be to either fit a second hand pipe (which I can buy for £100 but means dropping the back axle to fit) or to get a hydraulics firm to make flexible pipes. The latter may have to involve cutting good existing AC pipes in the engine bay to connect to hydraulic pipes to using some type of yet to be researched compression fittings or fittings along the lines of those Bri suggested because the inny/outy pipe runs just about all the way to the engine bay. But if the latter worked I could fix lots of other same model vehicles with the problem and would be an easier more definite fix than the former.

Yeh, autumn will see the result!

I think I googled the problem with this model - I'm sure I've seen one post where the owner capped off or somehow otherwise blocked the pipes at the engine end to effectively eliminate the rear a/c evaporator, to get the system at least leak free.

Might be a way to go to at least get some a/c working in it? Would need less refrigerant in it come fill up time.

Sounds like an utterly crap design all round to me. Re. the mig/alu thing.. I have a spool gun that goes on my Cebora mig, which I've attempted to use a few times just to get the hang of it. It is a whore!

There's a guy on Elgrandforum, bit of a guru on Elgrands, sells parts for them and has advised me when I've changed suspension etc. He was intending on having an engineering firm make up the blanking plugs you mentioned, thanks for reminding me.

I once tried aluminium welding an internal heater pipe from a Vauxhall Senator, noticed the problem when squirting hot water scolded my leg! Didn't work very well and I ended up getting another pipe from a scrappies. A difficult skill to master but when I worked at Chamber of Commerce there was a learner there doing his NVQ at a welding firm who had a natural talent for it, might help to have him around now!

Had a long chat with the Elgrand guru yesterday, we both took time out from sweating over vehicles (me converting a Jag XJ8, him changing a rear wheel bearing on some pocket rocket which he hadn't anticipated would have to involve removing the whole rear leg due to it having suped-up oversized special disks meaning the re-positioned caliper bolts, which were now Torx bolts, were obscured by the bottom arm. Couldn't take the caliper slides off until he'd dismantled rear suspension lol... hope he quoted for that one!). Anyway... My car already has Nissan replacement (I found out from him Nissan make this replacement so it's OEM) sectioned front to rear AC pipe that has a joint over the rear axle (the original front to rear AC pipe would have been one piece without the joint over the rear axle so to swap like for like the rear suspension would have to be dropped). He has favourable terms with his local Nissan dealer and is going to try to get me just the section of AC pipe I need (rear section) through them. I could probably try a Nissan dealer myself but the car's a Jap import and I expect his chances will be much better than mine. The engineering firm hasn't got around to making the blanks he ordered yet, they have big batches of other stuff to make first. Maybe at this rate I'll be sweaty all summer and finally get AC working in time to help with demisting. Thought just occurred to me that I'm going to Cornwall for a week in a couple of weeks and there's little chance of bits arriving from Japan before then so maybe I'll have another go or two at sealing the pipe or resort to dropping the rear suspension if I get time.

Make your own blank..... You're an engineer ain't you?

It's not just a straightforward blank, the end of the inner pipe is set back inside the outer pipe... so any blank has to have a centre bit which protrudes to the inner pipe for inner pipe's O ring to seal to. There's a bit more to it than that too because the inner pipe is attached to the outer pipe with 3 ribs that run the full length of the pipe. It would probably by easier to fix the pipes than make a blank, I imagine the engineering firm is casting them and then drilling the protrusion. If I made just a straightforward blank that didn't seal the inner pipe the front aircon wouldn't work anyway because the refrigerant would just circulate around the rear aircon pipe... But I might try!

Assuming the inner pipe is the one that has to be blanked off probably the easiest way to tackle that job is to make two or even three part unit. Basically a union of whatever size is convenient screwed or otherwise fixed onto the outer pipe with an internal thread enabling a solid blanking rod to be screwed up against the inner pipe O ring sealing the pipe off. Loctite should hold and seal the threads. Do what you will with the outer pipe union. Either capped off too or drilled for flow elsewhere with a matching non standard thingy to make the joint Come out sideways if you have to. Who cares about ugly under t'car if it works!

Done something similar to this before when a concentric pipe systems needed to be sealed and measuring up to make properly dimensioned projection was just too much like work.

Clive

I like your term 'concentric' far better than the 'inny outy' term I've been using hehe.

Both pipes have to be blanked off and there can't be any flow between them. At one point I tried something similar to what you've suggested, I cut the outer pipe back to get access to a length of the inner pipe long enough that heat from trying to braze the outer pipe wouldn't re-melt the braze on the inner pipe or vice/versa. The braze has a lot of surface tension but still wants to roll away into the pipe or spill out the end. Tried various takes on this such as partially crimping both pipes just below where the braze needs to take / tried to braze a large self tapper into the inner pipe. Dare say a grub screw would prevent braze running into the inner pipe but would still leave the problem of the outer pipe. Could try a cap with a hole drilled same diameter as the centre pipe to braze on but the problem with this is that the centre pipe is attached to the outer pipe at 3 points that run the entire length of the pipes and cleaning the inner pipe up to make round to make for a neat hole in the cap would be very difficult.

I'm wishing i went with something like JB Weld / quick metal / etc when the issue was just a pinprick in a simple narrow length of pipe (after the concentric splits into 2 pipes).

Might have been having another crack at it now if it wasn't for having to finish this Jag conversion off today. If I'm very lucky the guru fella will come back to me soon and say he can get the short section of pipe I need from Nissan in just a few days... But realistically it'll probably be £400 and 2 months just in time for autumn lol.

I had another crack at this before I went away, still failed but nearly got there!

Cut the concentric pipes at the same point, tapped the inner pipe, made a grub screw to fit and screwed it in until it's head was about 7mm inside, filled the inner pipe above the grub with braze, cut open a piece of aluminium pipe, knocked it flat, cut a circular disk from it to fit not quite to the edges of the outer pipe, held the pipe with cut end up and placed the disk in the middle before brazing it on.

If I hadn't overheated and slightly melted the top of the outer pipe in the process I reckon this would have worked. But it's not gonna work now because with a blown engine there's nothing to turn the compressor lol.