DRC saga

[Jim Haseltine]

As mentioned elsewhere, my car has a split DRC hose (left front) and another (right rear) that isn't looking too smart so I got hold of a couple of hoses and as it was a nice day thought I'd crack on with changing them.
Left front: Releasing the shock end wasn't too difficult. The other end - the body hard line didn't look good, on closer examination there was a suggestion of a twist to it. The flare nut was tight, not fast, but even with lubrication it was dragging on the line. The new hose fitted to the shock reasonably easily but the other end was a pain - three times it cross threaded so three times I had to take it off again and run a new flare nut through it to deburr the threads.
Right rear (fitted by JCT600 around 8 years back): Again, the shock end wasn't difficult - and it shouldn't have been because I fitted a new shock about 18 months back. Hard line end - line didn't look good and the flare nut had been rounded but I managed to get a flare spanner on it. Wouldn't move. Ah, yes it did - but not easily, by the time I'd got half a turn on it I decided to give up, tighten it again and tackle it another time.
Drained the oil, it sat at -1bar while I made a coffee, so didn't seem to have any leaks. Filling and pressurising seemed to take longer than normal but got there eventually. Checked for leaks and there it was - dripping from the hard line end of the right rear. Depressurised it again, put a spanner on the flare nut and....

Luckily, it's the shortest of all the lines and I have a coil of 1/4" Kunifer along with flare nuts in my garage so tomorrow I'll see what I can make up.

[Jim Haseltine]

So what I thought would be at most a morning's work turned out to be two days. This morning I dropped the rear of the exhaust and removed the right side heat shield so I could trace the line. No way was the flare nut coming out of the valve with a spanner (and from the looks of things none of the others will either if they ever have to) so I cut the line close to the nut and removed it with the aid of a 6-side socket and a 3/8" breaker bar. Even missing both flare nuts the line was still difficult to get out as not only was it clipped in place but it ran under other lines and as I wanted to use it as a pattern I didn't want to bend it.
My replacement approximately the same pattern as the original (not perfect though) but it'll do for now.
I managed to get the system recharged using almost all of my last litre of suspension oil.

[ATinOf]

Good job Jim, likely this type of fix is going become common the age of our cars, but we dont all have the luxury of access to the recharge equipment like you have, so its just going to become a more expensive repair for us. One to watch for when this does occur is whether the repairer recommends a full line change, or a short 'repair' line (extra coupler, extra potential failure point)

[Jim Haseltine]

I did consider trying a repair to the line but I've tried and failed to flare steel lines with the kit I've got so decided to go for the full replacement. Looks like some of the reasons behind the flare nuts seizing to the lines are to do with Audi's choice of material. The lines are plastic coated aluminized steel and the plastic continues under the flare nuts so when moisture gets into the flare it starts to corrode the aluminium coating which expands into a white powder and swells under the plastic so binding the flare in place. I eventually managed to free the old flare nuts from the remains of the lines by heating them with a blow torch until the remaining plastic melted but it's not something I'd like to try on the car.
There are, in fact, 6 hard lines as the front lines are two part which might (just might) make replacing the iffy front left line a bit more simple - if I ever have to do it.
As a precaution (call it advanced planning), each time I'm under the back of the car in future I'm going to give the flares on the central valves a good spraying of some sort of penetrant. Maybe it'll work but judging from what I've seen over the last couple of days I don't hold out much hope.
Looks like the line I replaced is still available - at something around £250.

[ATinOf]

WD40 is great at clearing oxidised aluminium Jim, but I'm guessing although you can spray it, you cant get the resulting gunge out, so may not be much help.

Im with you on flaring steel lines; Ive got a couple of flaring tools; one you can use for a pipe 'on the car' but not capable of steel; one you use in a vice that will do steel; but the effort required for steel, or annealed stainless, is still hard work even in a vice. Its also not helped by the pipe being seam welded if thats what you have as this leaves an uneven face at the seam; not a problem with copper/nickel pipes that will seat itself regardless; but steel does not work like that - you need to then use flare washers (copper) on the seat. Oh the joys.