How to undo seized brake-line to hose nuts? Any ideas?

[griston64]

Originally Posted by Laird Scooby

That's not just a manifold Alan, if it's non-ABS it's a brake pressure reducing valve for the rear circuits and if it is ABS, it's a copy valve. The system is essentially the same between the 7 and 9 series cars but the problem of getting the rubber flexi hose disconnected from the hard metal line in the wheelarch still remains because they meet in a bracket that holds things in place.

If you can undo the pipe from the reducing or copy valve you can then cut the brake line just before the bracket in the rear arch and then get in a vice with heat to dismantle it

You would then need the little U clips ( https://www.skandix.de/en/spare-part...-hose/1018942/ )and a new brake line made up.

Thats what I had to do on my old V70 front brakes

[jasons]

my three top tips are:

1. grind back the face of teh spanner so you get complete contact of the ring against the nut

2. Use heat against the metal base of the flexi and lots of WD40 or similar after the heat.

3. Be careful, ideally drain down the system.
I have just done all the flexi's on a 240 (6 of them) and 1 flexi blew with a bang on the cool down, now I didn't have a drop of fluid in the system but if it had hot fluid and your face was close it would be a nasty experience.

That hose probably would have failed in time anyway, they are 30 years old and good preventative maintenance is to replace them, and also all of the brake fluid.

Hope that helps, grinding the brake spanner face will make a big difference

[Laird Scooby]

Originally Posted by jasons

my three top tips are:

1. grind back the face of teh spanner so you get complete contact of the ring against the nut

2. Use heat against the metal base of the flexi and lots of WD40 or similar after the heat.

3. Be careful, ideally drain down the system.
I have just done all the flexi's on a 240 (6 of them) and 1 flexi blew with a bang on the cool down, now I didn't have a drop of fluid in the system but if it had hot fluid and your face was close it would be a nasty experience.

That hose probably would have failed in time anyway, they are 30 years old and good preventative maintenance is to replace them, and also all of the brake fluid.

Hope that helps, grinding the brake spanner face will make a big difference

If you really must use heat, undo the nearest bleed nipple to give the pressure somewhere to go. After changing a hose/pipe it will need bleeding anyway so there's nothing to be gained by leaving the nipple in and a lot to gain because it releases the pressure.

[eeedelli]

Thanks guys.

This is the 89 740 without ABS so there doesn't appear to be a joiner near the back - the pipes appear to run all the way, individually, to the block on the front inner wing, as shown here: https://www.catcar.info/volvo/?lang=...Q1NWI4ZQ%3D%3D (The RHD version is in the box in the bottom LH corner.)

I'd already removed the calipers and drained the system anyway. I took the precaution of wrapping wet rags round the start of the hoses too. No explosions.

Good news - all done! I couldn't get any fully-synthetic ATF from either of the motor factors near me so I decided to have a go with the blowtorch and PlusGas Formula A I already had in. After a couple of cycles of that, they turned like they'd only just been put on there!

I've bled the whole brake system (and the clutch too). It certainly seems to be stopping now!

Although it feels as though it's back to how it has been for several years, it still has quite a lot more pedal travel than my 940. Braking is quite efficient within an inch or so of the top but, with the engine running, it's possible to depress the pedal quite a long way (with a gasp of air to the servo if you do it hard and suddenly). With the engine off and the servo exhausted, it's relatively firm and near the top.

Anyway ....general feeling is 'phew'!

[kiloran]

Good to hear you've got it fixed, it's a job which is going to need doing on mine for the MOT. Seized piston in my case and the flexi has seen better days. Just need to clear the drive so I can get her on a flat surface

[Ian21401]

Good to hear of your success eeedelli.
That’s a method I’ve used in the past on stubborn fixings, but not on brake lines.
Squirt the PlusGas on whilst the item I still hot.
I had difficulties a while ago trying to obtain some fully synthetic ATF-U. The current bottles of Carlube Driveline ATF-U do not have any indication as to whether it is fully synthetic. A search on Carlube’s web site eventually found that it is in fact fully synthetic. I cannot understand why it does not state that on the bottle. I’m fairly use that it did some time go.