Audi Stafford have messed up my car

[tonupkid]

Took the S8 into Audi Stafford yesterday for a service, MOT and new brake fluid.

They failed the cars MOT because it required the front number plate replacing and one of the read number plates was out... so they say.
The front number plate I can understand, but the rear light. It was working.
The sent me a video of it, with the bulb holder out, and as they moved it about it went on and off. Well those kind of bulb holders will do that if you wiggle them around.
The thing is, one of the screws holding the bulb holder lens in place had broken. A common fault. Therefore the thing was held with one screw and not perfectly flush. They suggested I fork out over £300 to replace the entire component onto which both the number plate lights are mounted. Without me having this job done they said they could not pass the car.

Anyway. I declined, took the car away and checking it over today noted that both number plate bulbs were working, and took it to a local garage for re test (MOT), as Stafford Audi is to far away.
My car failed the re test. Reason..... brake fluid squirting out of the NSF bleed nipple. How how has that happened. The tester attempted nipping it up, but it was apparent the the thread has been crossed. I drove home with care. Still no MOT.

I now have to get Audi Stafford to resolve this, after all it was yesterday that they replaced the brake fluid. I am concerned that the caliper may have been damaged. Is this likely with the nipple thread having been crossed?

[MikkiJayne]

Are they alloy calipers? If so, its entirely possible the bleed screw took the thread out of the caliper when Audi Stafford loosened it for bleeding. Its unlikely they would have removed the bleed screw entirely and then put it back in crossed. I had exactly this happen with a D2 recently - I managed to nip it up enough to stop it dripping, but it popped on the MoT brake test. The steel bleed screw corrodes in to the alloy caliper body and when you try and loosen it the very fine aluminium threads just give up. If that is what happened, its not really Audi Stafford's fault tbh - it would have happened to anyone, and there's nothing you could do to stop it once it got to that point. Probably worth talking to them about it though - they might offer to make it good, or at least offer some goodwill or heavy discount.

Theoretically it might be possible to helicoil it, but its not worth the risk with brake components so I would replace the caliper. The last thing you want is for it to pop again in an emergency stop.

[tonupkid]

Thanks MikkiJane. I'll speak with them in the morning and bear in mind what you say.

[tc4332]

MJ Some damn good advice there, Thanks.

Nick Be careful driving your pride and joy.

[HPsauce]

I had something similar happen when the brake fluid was replaced a couple of years ago on my D2, pretty much as MJ described. New caliper.

[27litres]

Would spraying with penetrating oil well beforehand prevent the thread stripping, or is it pot luck?
Sounds like reinstalling with antisieze is in order...

[tonupkid]

The dealer has confirmed what MJ said. Ally caliper - steel nipple - electrolysis nackers it.
They are sending the caliper of for re engineering and I presume, an oversized bleed nipple. Helicoils will not be used.

Since I called the dealer they've been brilliant, no messing or difficulty. And they've left me with a Q5 loaner. Its a gutless 2.0 diesel, but otherwise good. And it has B&O which is nearly as good as the one in the 8. With the addition of being able to play any of my songs off Google Play.

[David's8]

Its good that they are sorting it.
When I had my D2 Brembos front calipers refurbed, the refurbisher specified Brembo bleed nipples as the threads are coated to prevent/reduce the dis-similar metal issues.

[MikkiJayne]

Excellent news M12x1.0 bleed screw - I didn't think of that! I might be able to recover the similarly broken D2 caliper I have doing that.

Marty - penetrating fluid is always worth a shot, but usually they're so crusted up it can't get in there. Copper anti-seize is very bad in this situation as it exacerbates the electrolysis between steel and aluminium. If you can get aluminium anti-seize though then this is ok. I usually give them a squirt of waxoyl once they're back in too, to prevent moisture getting down in to the threads - I do this with all brake fittings. The original Brembo bleed screw covers actually have a little collar around them to do the same job.

As David said, the proper Brembo bleed screws have a special black coating to prevent electrolysis, the same as Audi original hardware has a greenish coating. Putting ordinary zinc plated screws in just makes the problem even worse!

[tonupkid]

Originally Posted by MikkiJayne

Excellent news M12x1.0 bleed screw - I didn't think of that! I might be able to recover the similarly broken D2 caliper I have doing that.

Marty - penetrating fluid is always worth a shot, but usually they're so crusted up it can't get in there. Copper anti-seize is very bad in this situation as it exacerbates the electrolysis between steel and aluminium. If you can get aluminium anti-seize though then this is ok. I usually give them a squirt of waxoyl once they're back in too, to prevent moisture getting down in to the threads - I do this with all brake fittings. The original Brembo bleed screw covers actually have a little collar around them to do the same job.

As David said, the proper Brembo bleed screws have a special black coating to prevent electrolysis, the same as Audi original hardware has a greenish coating. Putting ordinary zinc plated screws in just makes the problem even worse!

Mine are original Audi calipers. They mentioned the barrier coating, but with age (and I guess use, as in bleeding) it wears off.