Can washing your car destroy your brake discs?

[LotusOmega375D]

My October 2017 Passat lives outside, but doesn't have a very hard life. I wash it myself every few weeks and always try and get a quick drive in to help dry things off, when I have finished. Anyway, I washed it once before Christmas and left it for a day or so before using it again. The electronic parking brake was binding and needed to free itself, and then I got that pulsing sensation through the brake pedal, when applying the foot brake. No bother, I thought, it will clean itself up and any surface rust on the brake discs will disappear after a few miles. The car had done <7000 miles at that time.

In fact I had a couple of long journeys ahead, so I assumed it would sort itself out. Not so, even after 1000+ miles, the sensation had still not gone away. I booked it in with the dealer, where it is today. The mechanic had a drive with me this morning and confirmed that something was wrong. It's a similar vibration sensation you get when driving over rumble strips prior to a roundabout.

Anyway, the car's now been checked over and all 4 discs are knackered. All are out-of-tolerance and badly scored on the inside (outsides look fine). So since these are consumables, I'm faced with a big bill for new discs and pads on all 4 corners. The car's now at <8500 miles.

Has anyone else experienced this? Anything I can do to prevent it happening again (apart from keeping it in a garage and not washing it or driving it in the wet!)?

[htid]

Wow that doesn’t seem right for such little mileage that you’re left to foot the bill, I hope someone more knowledgeable comes along and helps you out with some possible explanations

[TwistingMyMelon]

I had a very low mileage Seat in past that was sat around for long periods of time, the discs got scored and were loud at times, Garage told me to leave it and told me they all do that sir. In fact the mechanic told me off for not driving hard enough!! I just said dont break for corners.

I would get a second garage to have a look, might at worst need the fronts need doing

[anonymous-user]

Washing your car/driving in water won't score or warp discs. All it will do is put surface rust on them , which comes off in seconds when you drive. Just parking a damp car in a garage results in rusty discs

[Pica-Pica]

Over 40+ years, I have only given my cars an infrequent hand wash and rinse. I never dry them. I have had an Escort, Fiesta, Volvo 740GL, BMW E36, Ford Ka 1st iteration, now have a BMW 335d, and Skoda Fabia. Never have I had anything deleterious to the whole vehicle, and never warped discs. The odd surface rust on the discs maybe, but that soon goes, even if the cars were left for two or more weeks.

[Sheepshanks]

LotusOmega375D said:

All are out-of-tolerance and badly scored on the inside (outsides look fine).

"Out of tolerance" in what way, and if they give you pictures or a video?

They might be a bit rusty and scored, but out of tolerance seems unlikely.

Our local use Tiguan has been OK after 4yrs/20K miles, but I've seen pictures on a Tiguan forum of discs at 2yrs old that make you think the car must have been parked in the sea. We don't normally use the EPB on ours though (it's DSG).

Just had to have the rears changed on a Honda Jazz after an inner pad got stuck and the dealer told us off for not jet washing the calipers.

[Howard-]

This will not have been caused by washing it. The most you're likely to experience is a slight graunching noise the first time you use the brakes as the fine layer of surface rust gets stripped away by the pads.

[LotusOmega375D]

Yes the VW technician supplied a video and refers to "a DTI brake disc run-out test being performed and found to be out-of-tolerance" on all 4 discs. It is clear from the video that the insides of the front discs are badly scored: almost as if the pads were worn to the rivets. They're not: there is 12mm remaining on fronts and 9mm remaining on rears.

[HM-2]

The only circumstances I could see disks being damaged by washing is if you immediately sprayed hot disks with cold water, repeatedly, which might cause them to crack or warp through thermal shock. But I think this is pretty unlikely!

I'd push. Even consumables have a reasonable lifespan they're expected to last for in normal use, and you never know, they might contribute.

[bobtail4x4]

do you sit in traffic with your brakes on?

that causes discs to warp after a run.

[Pica-Pica]

Howard- said:

This will not have been caused by washing it. The most you're likely to experience is a slight graunching noise the first time you use the brakes as the fine layer of surface rust gets stripped away by the pads.

That will often happen, and is certainly my experience with rear drums (either as service/parking brake, or as a drum-in-disc parking brake). That is never any great big deal, and never damaging.

I have to say, I have never experienced ‘warped’ discs, ever.

[LotusOmega375D]

bobtail4x4 said:

do you sit in traffic with your brakes on?

that causes discs to warp after a run.

Not me: it's a manual and has auto-hold. What's interesting is that it happened that one particular time and then stayed like that. Prior to that the surface rust on the discs would soon get worn away as expected with no issues. Strange.

[C.A.R.]

You say Christmas, I wonder if it was exceptionally cold? Was the car driven prior to being washed (could the discs have been warm and rapidly cooled)?

Seems mad.

[LotusOmega375D]

C.A.R. said:

You say Christmas, I wonder if it was exceptionally cold? Was the car driven prior to being washed (could the discs have been warm and rapidly cooled)?

Seems mad.

I don't remember the exact sequence of events, but even if I had driven it first, by the time I'd unwound the hosepipe and filled the car-wash bucket (no double entendres please) it would have cooled down.

[832ark]

I wonder if it’s due to insufficient use? If you’re very light on brakes and only doing 4/5k miles per year that could cause excessive corrosion. You tend to see it on the rear discs of lightly used cars. Also, there’s no way I’d be paying VW to do the work, quick google suggests decent discs and pads are just over £200 all round and then maybe two hours max for labour. If you’re being charged more than £350 for the job you’re being ripped off.

[Sheepshanks]

832ark said:

I wonder if it’s due to insufficient use? If you’re very light on brakes and only doing 4/5k miles per year that could cause excessive corrosion. You tend to see it on the rear discs of lightly used cars.

It will be this. If you don't use the brakes enough, and hard enough to clear the rust off then it sets in and gets worse. Once it's there is rubs the pad away so you end up braking a very narrow band of the brake disc - it seems common the outsides look OK, but the inside of the disc will be terrible.

GM in the US puts treated discs on many models as they had so many complaints about rusty discs.

The DTI runout will be picking up on the rusty surface - I bet the tolerance is miniscule.

[LotusOmega375D]

Thanks for your replies. I think you're right about the lack of use. All replaced now. VW claim only to offer 6 months or 6000 miles months warranty on discs, so no help from them. It's a company car, so my employer will have to pick up the bill. Still rubbish though.

[tapkaJohnD]

Quote OP, "all 4 discs are knackered. All are out-of-tolerance and badly scored on the inside (outsides look fine). "

Strange that all four discs are that way, buy such assymetric wear points to caliper malfunction,one of the pistons seized.

And washsing the car causing this? Not unless you do with sea water.
JOhn

[LotusOmega375D]

I've had a chance to sleep on this now and think I have come up with a plausible explanation.

I was brought up driving a diet of 1960s / 1970s / early 1980s cars. Cars of this ere were infamous for rusting, particularly around the wheel arches. I therefore got into the habit of hosing around the wheel arches to remove any dirt and salt.

I have carried on with this procedure through to the present day. I think this is causing the disc scoring: i.e. some of the dirt and debris from the wheel arches is splashing back onto the reverse side of the discs. This would explain why only the inside of the discs is affected, since the exposed side gets directly rinsed clean with the hose pipe after I have cleaned the wheel rims. Meanwhile the back of the discs remain coated with bits of hidden crap, which eventually ends up scoring the discs when embedded by the action of the brake pads.

What also supports this idea is that I had a similar issue with a 62 plate all-disc brake Polo 3 years ago. I didn't give it much thought at the time, since I bought that car second-hand and it had covered a good deal more miles. I just assumed that I was a tad unlucky and bought 4 pattern discs and pads and got them changed locally.

So, if true, the moral of the story is don't hose out your wheel arches, unless you take the wheel off and cover the disc brake assembly. It also means that it was my actions which led to the heavy scoring on the inside of each disc, so I can't blame VW after all.

[stevieturbo]

With less than 8000 miles on the clock and a brand new car ??

I'd be going apest with the dealer. Consumables fk all, they should not be needing replaced this early. And if the local dealer doesnt sort it, contact VW UK or the media etc.