Brake pressure/fluid loss

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Brookstain

Member
Posts
55
Location
Bristol
Hi guys, me again!

My brakes have always been really good, up until suddenly yesterday they started going spongey. This rapidly got worse and worse but whilst I was almost home I carried on for the final mile as they still worked. When I pulled up, I have found the reservoir to be completely empty and my brake pedal goes right to the floor (and basically doesn't work now).

Now there's obviously a leak somewhere, but I just wondered if anyone could point out where the first place I should be looking please?

I've ordered a bleed kit and some new fluid, but haven't had to bleed or fix brake lines or a cyclinder before so am a complete noob with this problem.

Many thanks in advance, Jack.
 
Clean the vehicle underneath and let it dry thoroughly, especially around the brake calipers and lines. I'd then refill the brake cylinder and get someone to help by pressing the brake pedal whilst you look at the brake systems at each corner to see where it's most leaking from.

This's happened to me twice, both times brake lines rubbed through by the tyres due to bent brackets etc ...
 
Immaterial of vehicle type, the general places to look for brake fluid leaks would be as Paul has already said, the flexible pipes either worn through or perished, then traces of oil contamination on or around a brake caliper which would usually indicate a failed seal. After that, around the area of the master cylinder and servo. That too would indicated a seal failure.
The metal brake lines on older vehicles are also prone to failure through corrosion, especially if they are original fittings and not been protected with anti-corrosion treatment.
 
You're all brilliant, that gives me a great start to what to look at. I'll jack her up onto axle stands tonight and give it a good clean and let it dry.

Its a 1996 300tdi - sorry for missing this off!

I've read a bit online saying that I may have knackered the master cylinder by letting the pedal go all the way down. Is this likely true?

Thanks guys.
 
Also chaps, another point that I should have probably mentioned before...

When the brakes started deteriorating, I could hear what sounded like air coming from the brake pedal every time I braked.

Now I think of it, this could point a finger at the master cyclinder?

I'll still check underneath and be thorough, but the above may help diagnose an issue?
 
It could be anywhere. I recently had a copper brake line fail and it took a few days before the brakes went completely. It was above the rear axle and was immediately apparent by the fluid that was dripping off the bottom of the axle. When I got underneath while someone pushed the brake pedal, I could see ixactly where it was leaking from.
I whipped the section of copper out and made a new one.
 
Could be the master but if you're losing all the fluid, you should easily be able to see it. If the cylinder bore was dirty or corroded then excessive pedal travel will put the piston on a rough bit of the bore and wreck the seals. But if it's leaking, it's knackered anyway.
 
So I removed the rear wheels and I saw the problem right away. Not one, but both of my rear calipers are leaking. Only changed the rear discs and pads a couple of months ago and all!

Going to replace these, rebleed using a new Ezibleed kit I bought and see how I go.

Cheers for all your help lads.
 
So I removed the rear wheels and I saw the problem right away. Not one, but both of my rear calipers are leaking. Only changed the rear discs and pads a couple of months ago and all!

Going to replace these, rebleed using a new Ezibleed kit I bought and see how I go.

Cheers for all your help lads.
where are the calipers leaking from and did you remove the whole caliper or just half
 
It looks as if they are leaking from the pistons... was hard to tell, as I didn't even bother removing the calipers as I could just see the fluid all over the inside of the wheel and the disc.

I was rushing around a bit so saw plenty of fluid and decided it was time for some new calipers!

I remember one of the pistons being quite stuck out when I replaced the pads and discs, so I'm assuming they've had their time.

Just really hoping I don't need to now replace the master cylinder!
 
Sorry lads, last question until I get the tools out.

Will I need new brake pads? Or do you think I can clean them with brake cleaner and give them a rub down with emery paper?

I know pads are relatively inexpensive, but I've only just replaced the rear pads for Mintex ones.
 
It is indeed peace of mind and relatively cheap too.

While you can clean off some oil/fluid, the pad material is porous to a degree and you'll never get it all out, plus the solvents will attack the bonding material.

Peter
 
Sorry lads, last question until I get the tools out.

Will I need new brake pads? Or do you think I can clean them with brake cleaner and give them a rub down with emery paper?

I know pads are relatively inexpensive, but I've only just replaced the rear pads for Mintex ones.

Deffo change them.
 
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