The hoses are standard, two sizes. Check the simple things first.
Morning chaps. I finally got to strip back the centre console panels and remove the radio yesterday (and discover how shockingly ineptly the radio had been wired in, haha…), to find that the vacuum installation has been recently fettled - the pipes and ‘heater sensing unit’ are new, but two of the pipes have escaped their fittings.
I’ve not removed the two modulators yet, to see whether there is more singificant damage, but it appears that the actuator pipe has come off the air flap modulator (purple) and would explain why the vacuum suck can be heard when the level is to ‘air’ and disappears when switched to ‘car’. Also, the control (rather than vacuum supply) pipe has come off the heating modulator (green). I can’t see why the heating control pipe would come off the connection nipple, so I’m expecting to find damage there. The challenge with the air flap modulator is that the nipple has clearly broken off and is stuck in the end of the pipe. Moreover, it appears to have been haphazardly repaired in the past with a liberal dose of Superglue.
I would assume that the pipe nipple re-connection can be achieved with patience and either solder or a wad of plastic putty, unless there is a more competent solution out there…?
no own experience on SI cars, but based on SII experience I would be more than surprised if any of the vacuum hoses just fell off. In fact, it is a royal pain in the neck to prise them off without breaking the nipples they are fitted on. Your ultimate statements confirm this guess.
Obviously, repeated attempts of glueing were of no avail. I’d take this for granted and try to source a good original air flap modulator.
75 XJ6L 4.2 auto (UK spec)
Might be difficult. I fitted a 3-way pneumatic switch and attached the original lever from the flap valve. Looks like factory, but doesn’t have a range–it’s either complete fresh air from the scuttle or complete recirculate. These switches look like an electrical toggle switch and are only slightly larger. You need the kind that switches the vacuum motor to vacuum in one position and open air in the other. That’s so the motor canister can lose its vacuum quickly rather than having to slowly leak down.
What is needed is an airtight connection between the components, Paul; standard ‘competent solutions’, apart from component replacement, are not given…
You may consider drilling a hole and fit/glue in, a suitable replacement spigot/tube - it may give better ‘hold’ than butt end gluing, which seldom works. There must be adequate material, and must avoid damage to the actual working of the components. It will then work and look neat - but require removal of the components for drilling…
The other way is to put a large wad of material on/around the area, with a spigot fitted. The problem is to find malleable material that will consistently adhere to the components - which must be clean. It may look ugly - but it will work…
xj6 85 Sov Europe (UK/NZ)
Glue in a little tube (ballpoint pen, brass tube or similar… drill into valve a bit if required) and slide the nipple over. Use superglue and baking soda to build up a blob around the valve, this will harden into a very strong reinforcement instantly and can be built up in layers.
Something like this (if room in the engine bay) may make a good replacement for the Vacuum unit that controls that air flap. I haven’t measured the slider, but looks like it would work in place of the one that controls the vacuum at the dash.
Are you even remotely serious?
Anything but the original valve makes no sense, by the way. Either you lose functionality and create a mongrel or just create a mess that takes a lot more time than it would be worth, something I do often but here it’s just pointless. Repair what you have.
Thank you - spot on. I think the pipes are older than they look and slid with consumate ease off the heat modulator nipples. I vigorously pushed them back on, but there be dragons ahead, no doubt. Time to look for new pipework.
Fortunately, I was able to repair the broken air flap modulator nipple in exactly the fashion you describe. I confess that it is not exactly a jewelry-standard repair, but it now has a permanent metal catheter to reinforce the repair.
Happens to us all in the end, I suppose.
That‘ll do - perfectly!
I‘ve never had to do this (yet), but that is how I would’ve approached it. Happy to hear it is working!
that sounds a bit as if someone replaced the original pipes with new ones that run a bit wide in internal diameter, doesn’t it?
But yes, once you’re in there and you feel that the pipes are anything less than secure on their nipples, replace them with better fitting vaccuum pipes.
75 XJ6L 4.2 auto (UK spec)
Thanks - I think the original diameter is okay, but the pipes have probably hardened where they have flared slightly to go over the nipples. But there’s enough slack in the length to allow me to shave off the last 15mm and refit ‘virgin’ pipe.
You might find that the bellows in the flap actuator has failed. This happened on my S1. They perish at the edges and won’t hold vacuum. The canister has a swaged closing joint - sealed for life - as they say. I ended up turning that away on a lathe and then I repaired the perished edges on the bellows with a flexible glue product called “Stormsure”. It’s used for repairing holes in “rubber ducky” inflatable boats. I bonded the whole thing closed and it still works after three years. Unfortunately, the control units involve rubber diaphragms that are now 50+ years old. Many are unobtanium. Good luck.
Interesting - thank you. Being in a communal basement parking garage in the depths of winter, I will only be able to check briefly for the sound of leaks. Proper checking will have to wait for spring.
I was able to come up with a satisfactory repair for the vacuum modulators. I sourced metal tubing that was the same OD as the original plastic nipples. It turned out that a certain replacement metal ball point pen refill was perfect. I cut pieces and cleaned out the ink. Next, I carefully removed as much of the old nipple as I safely could and flattened the end. Using a drill the was a little larger then the OD of the metal tube, I drilled just deep enough to set the tube in place and then set it with JB weld all around. I have had not problems with the repair. One has to be careful not to drill too deep. Having a metal nipple instead of a brittle plastic is the key. Sorry I don’t have any pictures.
Thanks for the guidance, everybody. We had a respite in the snow and enough rain to wash the roads reasonably clear of salt, so I was able to confirm that the repair is successful and the bellows are sound - I have heating.
I also took the opportunity to get the first service and mechanical evaluation done. Everything is good. Nearly. But I’ll save that for the correct thread.