I've just had my MoT and the front brake lines were an advisory.

Repair as soon as possible (minor defects):
Nearside Rear Registration plate lamp inoperative in the case of multiple lamps or light sources (4.7.1 (b) (i))
Monitor and repair if necessary (advisories):
Brake pipe corroded, covered in grease or other material both front


I was present at the vehicle with the tester and asked his advice on this. He said there was no flaking on the (visible) lines, just a discolouration. He also said this was typically seen, even on a first MoT for a three year old vehicle! I suggested changing to Cunifer and he said that, despite popular opinion it only gives an extra year or two before it corrodes too! The older I get, the more I realise that people confuse wrinkles for wisdom

FYI : https://www.racinglines.com/cupro-nickel-kunifer-brake-pipe

90% copper 10% Nickel - I’d be surprised if corrosion were an issue on these. TDV8 4.4 2012

CUPRO NICKEL FUEL / BRAKE PIPE HOSE LINE 25FT length £15 quid on ebay - I got 2 rolls

Last edited by pcourtney on 8th Apr 2024 6:32pm. Edited 1 time in total

Ramblin Man wrote:

FYI : https://www.racinglines.com/cupro-nickel-kunifer-brake-pipe

90% copper 10% Nickel - I’d be surprised if corrosion were an issue on these.

This is what went on Fatty in 2018, only change to the appearance is it got dirty. Ignore all the snake oil experts its BS.

How the hell can a brake pipe ever not fail straight away on corrosion? WTF?

You do have to wonder.....

The MOT manual says....

Rigid brake pipes

Chafing, corrosion or damage to a rigid brake pipe so that its wall thickness is reduced by 1/3 (approximately 0.25 mm for typical hydraulic brake pipe) will fail. As it is sometimes difficult to assess this accurately, if not sure, the Tester will give the benefit of the doubt.

So, an MOT tester can tell just by looking that the pipe is not rusted more than 0.25mm...

But it's OK if he can't, he just gives the benefit of the doubt....  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

A couple of things. Copper pipe work hardens, particularly at the flares, and vibration can cause failure. Cuprinol is much, much better and the addition of nickel makes a big difference on this to the point it's a non-issue. However, it just isn't as tough from a damage point of view which is partly why manufacturers use steel. It can get ground through more easily, dented more easily and generally gets battered a lot more easily. None are good things in a production environment. Coated steel will last well. The lines on my Impreza are all original and are 20 years old which I find pretty impressive. The biggest issue is that newer cars are suffering line failure earlier than they would have in the past as a result of cheaper steel and lines being tucked up under protective panels more which keeps them wet longer so when the coating does inevitably get breached, they fail more quickly from that point on. I've had replacement lines on cars under 7 years old in the past but generally I think lines last a reasonable amount of time given where they are on a car.

As for the MOT point, it all comes down to judgement from experience. If it's holding fluid and doesn't look like it's about to imminently spring a leak within 3-4 months then it'll usually be passed. An MOT is not a guarantee, but also if they were failing lines for just being a bit corroded then you would have an awful lot of complaints. My experience of working on cars over the last 20 years (not as a professional I hasten to add) is that it's usually pretty easy to tell which lines are done in.

And that was my point… Why not er on the side of caution and fail any brake line that’s compromised? I bet they do in Germany / Switzerland etc etc…

Because slight surface corrosion doesn't mean that the line has suffered any diminished ability to contain the fluid at the normal operational pressure.

Most brake pipes will have an amount of corrosion after 5 years, if every bit of corrosion was an immediate fail people would soon get off with renewal of brake pipes that are still very capable of doing what they are designed for..

As a matter of interest what pressure do brake components operate at ?

An emergency stop puts about 2000psi through the system, normal use under 1000psi......

I still think the MOT should err on the side of safety, not give the benefit of the doubt to a potentially weakened pipe..... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Exactly Peter... 2000PSI or maybe 2500 in an emergency, when you're the size of us lumps Peter!

An MOT is only ever a basic set of tests and no guarantee of safety or reliability. You can get an MOT 'pass' (with an advisory) with 4 windsail tyres with 1.6mm of tread but try doing an emergency stop in the wet and a week later when they are below 1.6mm that's potentially a £10k fine and points on your licence. 2012 TDV8 Vogue (L322)

Good point well made Jay… Does seam like a heavily outdated scheme these days though ay!