Sudden brake failure

[timski]

Hi Guys,

I was driving along at about 60mph when I touched the brakes and my foot went down more than expected. I thought for a minute I had somehow hit the clutch by accident. I slowed down and exited at the first lay-by. I had just enough brakes to draw to a stop. I could push my the brake pedal right down. I had no warning light but when I checked the brake fluid level there was no brake fluid (or very little). I called the breakdown service and had the van recovered to my home.

I had an advisory on my last MOT that there was some corrosion on one of the brake pipes so I assumed it had burst and that would be the reason the brake fluid was suddenly gone. My wife called out a mobile mechanic as I was away for a few days and he investigated, topped up the fluid and then did a check and said he couldn't find any sign of a leak. He bled two of the wheels (two bleed nipples were seized so couldn't be bled). Apparently he did a special tool to check the pressure so was happy it was properly bled. I called him to see if he had an explanation as I couldn't understand how there could suddenly be no brake fluid if there wasn't a leak. He said the brake pedal wasn't spongy when he checked and there was some fluid but was very low. He couldn't explain why it had happened and said the only explanation he could think of was that the wheel bearings had caused heat and I had experienced brake fade and could be why the fluid was low. He said he did notice the wheel bearings sounded knackered when he took it for a test drive. I had noticed a little whine recently but wasn't sure where it was coming from or what it was. I took it for a fairly long spin tonight and the front offside dust cap was fairly hot. I couldn't keep my hand on it for long. The nearside was very warm too but I could keep my hand on it. Rear ones were just warm. I've no experience of this so no idea if that is normal or not?

So I read some previous posts on here to see if I could find some pointers and a couple of people mentioned the slave cylinder was leaking evidenced by fluid in the footwell. Interestingly I've had a very damp footwell recently but assumed it was coming from a leak in the corner of the front windscreen, i.e. hidden under the window rubber. So maybe I've got a leaking slave cylinder.

One other person said the fluid was leaking through the warning light cables connector. I did notice that my hands were greasy after I checked the fluid level under the dash so perhaps that's another possibility. That could also leak down into the footwell I guess. I did top up the fluid 5/6 months ago when the warning light came on. And I remember removing the connector to undo the lid so perhaps I didn't put it back on right?

I've just moved to Salisbury so looking for a reliable local mechanic. I'd be interesting to hear your feedback in the meantime.

Thanks,
Tim.

[kevtherev]

I have never topped up fluid without there being a problem otherwise it just stays more or less where it is
Leaking rear wheel cylinder caused my last top up.
The seized nipples may result in replacement of the component they are in, it depends on the competance of the person tasked to do it
But it has to be done
Seizure suggests your fluid has not been changed in accordance to the service interval ...naughty.

The braking system is basic.
And ANY garage should be able to overhaul it.
Make sure you get the parts for it.

If it was me I'd be going the whole hog
Wheel cylinders
Brake Switches
Master cyl
Flexi hoses
New fluid
New lines where applicable

The slave cylinder is for the clutch.

[CovKid]

Agree. Plus I think an 'advisory' on brakes isn't like an advisory for more mundane items as your life depends on good brakes. Put it this way, regardless of whether they need replacing or not, if my rear hubs have to come off for any reason, I always fit new brake cylinders. Its such a hostile environment in there, cylinders don't tend to last that long and they don't cost all that much. Complete check/overhaul of hoses and pipes essential I'd say. "If in doubt, throw it out" - best rule with brakes. You can do it yourself even with the basic Haynes manual.

[timski]

thanks for the advice guys.

Would you buy the parts yourself or let the mechanics order the parts in?

Also, sounds like I would need new calipers if the bleed nipples are ceased? Would you get new discs too. Everything looks a bit rusty to be honest.

Thanks,
Tim.

[multisi]

Ask the guys at Brickwerks to put a complete brake overhaul package together for you, including brake pipes . Then let the garage do the work. Drive safe !

[bigbadbob76]

I've had brake fade due to boiling the fluid on a long downhill on a bike, scary stuff but it was fine 5 mins later and I didn't lose fluid.
Sounds like your reservoir to master cylinder seals are leaking but the heat suggests sticking calipers too so would be well worth a complete overhaul as suggested. worth it for peace of mind.

[kevtherev]

Ask the guys at Brickwerks to put a complete brake overhaul package together for you, including brake pipes . Then let the garage do the work. Drive safe !

Always get your own parts and ask for them to be fitted.

[what2do]

Ive just been around and had a look at Tim's van, there is definite signs of wetness where the master cylinder sits in the seals, not a lot but it is wet. Didn't jack the van and inspect anything but going on what Tim says, there isn't any play in the front wheel bearings to speak of and so I'm wondering if the heat he's experienced is being caused by a collapsed flexi not allowing the return of brake fluid after pedal application. Anybody have an alternative explanation?

[bigbadbob76]

if the caliper dust seals are shot then the piston can corrode and make it stick and not retract properly, the heat from dragging pads can then make the fluid expand and overflow or force it's way out of the reservoir. you wouldn't lose the lot though.
Also the front and rear brakes are on different circuits so failure of one circuit shouldn't drain all the fluid.

[kevtherev]

if the caliper dust seals are shot then the piston can corrode and make it stick and not retract properly, the heat from dragging pads can then make the fluid expand and overflow or force it's way out of the reservoir. you wouldn't lose the lot though.
Also the front and rear brakes are on different circuits so failure of one circuit shouldn't drain all the fluid.

Yes seized caliper would cause the heat.
I doubt the bore seals are sitting in a nice clean place, if the fluid has not been changed regulary they will cause the piston not to release the disc fully, due to all the crap underneath the seal

[what2do]

Good info temporarily stored in the memory bank (temp because I'll no doubt forget some of it ), when I changed my brake fluid shortly after I bought the van I was stunned his much watery liquid was present, it clearly hadn't been changed in a looooong time. I suppose thus moisture may cause some corrosion behind the piston seals, doesn't it?

[kevtherev]

Good info temporarily stored in the memory bank (temp because I'll no doubt forget some of it ), when I changed my brake fluid shortly after I bought the van I was stunned his much watery liquid was present, it clearly hadn't been changed in a looooong time. I suppose thus moisture may cause some corrosion behind the piston seals, doesn't it?

Yes it does
Many a caliper has been foolishly replaced because of a little crap under a seal

[Oldiebut goodie]

Guano under a seal?

[timski]

Hi Guys,

I'm looking at putting a parts list together on brickwerks. What should I be looking for to tell whether the drums and discs need replacing? I guess I could let the garage decide but ideally I'd like to buy all the parts in advance to save on paying shipping multiple times.

Here are some pics I took to determine what calipers I have (Michael from Brickwerks is going to id them for me) but perhaps you can tell from the pics if the discs are ready for replacing?
https://goo.gl/photos/VhcoTXvY7oLT3QZUA

Cheers,
Tim.

[kevtherev]

The discs should be replaced if they have exceeded the wear limit (spec in haynes)
Same with the drums

No need to replace what isn't necessary