How much brake fluid?

[dinkus 10]

Ok, I'm off to Halfords in a few mins to purchase me some 5.1 fluid. The question is, how much do I need to completely flush the brake and clutch system?

 

I saw that Henny said you needed a litre in a post a while ago, but a few other people have said you need 2. As the stuff's £8+ a litre I don't really want to go buying more than I need to...

[Joe M 0]

We managed to do mine with a litre and that was with the system completely empty as the brake lines were being changed at the time.

[dinkus 10]

Ah cool. Just the one it is then :)

[mrbeige 0]

The only thing is you don't want to run out half way through the job. If it was me (not that my brake skills are any good!) I'd get two litres to be on the safe side.

[dinkus 10]

I was gonna get a garage to do it... I've heard too many stories of impossible air locks :?

[RW1 0]

Officially a full flush of the system is 500ml per brake caliper line. Plus the Clutch circuit. So I guess I'd say you would be safe leaving them with 2.0 ltrs. I can do it in 0.8 ltrs but I do it regularly ain't too bothered at getting the last drop out.

[Yandards 0]

Dinkus, after a VAG fluid change 18 months ago this was the state of NickVR6's brake fluid...

 

http://the-corrado.net/.archive/forum/download.php?id=19063

[dinkus 10]

Yeah, I saw the state of that :?

 

As I'm getting the front callipers changed at the same time, I figured it was a good opportunity to drain the entire system and fill it up with 5.1. Then I'll have new callipers, pads, disks, flexi-hoses and fluid 8)

 

I might bend over a bit further and go for the full 2 litres then :(

[corradophil 3]

I'd go for 2 litres, you can always take the 2nd one back and get a refund if you don't need it, better to do that than run out half way throught the job.

[dinkus 10]

Yeah, I think that's what I'll go for. Right after it stops peeing down with rain..

[2cc 0]

Don't know where you are taking her, but can't the garage just put in the fluid you specify and charge you for how much they use?

Or don't you trust them that much.

[dinkus 10]

I've never used them before, but my neighbour is a mechanic there and he seems to love his 'dubs, so I was gonna give them a try.

 

I could ask them to supply the fluid, if I specify 5.1 then it can't be that bad and I wouldn't have thought any worse than the Halfords stuff... hmm...

[corradophil 3]

Yeah, but will they put 5.1 in, or will they just use dot 4. From their point of view you will never know, and dot 4 is perfectly addequate for a road car.

[dinkus 10]

Precisely...

[RW1 0]

Dinkus, after a VAG fluid change 18 months ago this was the state of NickVR6's brake fluid...

 

Yes not good but I'm surprised at that!

 

I've recently come across one brake caliper being darker than the other at the front. (Not that much though). When investigated, I found that the flexible rubber hose was sweating which means the inner rubber hose has a small hole somewhere. May be worth just making sure the brake hoses on that car are bone dry.

 

Likewise dinkus, about 3 - 4 weeks after you've got the fluid changed, just check the hoses front and back plus clutch (5 off in total) are dry and no "wetness" is showing, sometimes a patch the size of a penny and no bulges have appeared. New fluid has a habit of doing in older brake hoses sometimes. Tends to be less used cars, something to do with standing and the brakes out of use.

[dinkus 10]

Ah thanks RW1, worth looking out for.

 

Are you just referring to the flexi hoses tho? If so, I'm getting all of mine replaced with Goodridge ones...

[RW1 0]

Original rubber VW ones dinkus. Interesting design feature to alert of a problem but don't know if it is VW being deliberate. ie. a "tell-tale" check.

 

Goodridge will be OK as will fitting new originals at the time of the fluid change is the issue. It's new fluid with old hoses fitted that you have to watch out for.

 

I'll post a photo tonight of what happens internally during a failure case. B****y nuisance with partly stored cars.

[RW1 0]

OK dug out the relevant photo’s.

 

The history was in each case like this, change the brake fluid and then about 2 – 4 weeks later the hoses had brake fluid “wetness” in small patches plus the ballooning as per the second photo.

 

The first photo shows a rear brake hose which as started to “tell-tale” sweat along the length, the condition of the front hose before it was taken off the car and cut open.

 

The middle photo shows what happens when the inner hose punctures enough to leak pressure into the cloth braided area. The fluid gets trapped and builds up into the ball as seen under the outer rubber hose.

 

In the bottom photo, clearly the construction can be seen in the lower two hose halves. Outer rubber hose, cloth braided centre and then the inner brake hose carrying the brake fluid. The braided cloth acts as a movement aid as the inner and outer hoses move relative to each other and stops the two hose walls sticking as when turning. The top two halves are a faulty hose, nothing was visible externally but the inner hose can clear be seen collapsed.

 

As I wrote earlier, this seems to occur with new brake fluid on older hoses (5 years plus) and when the car is lightly used. So this is why an inspection about 2 to 4 weeks after changing the brake fluid on standard VW rubber hoses is wise, particularly older rubber hoses. Those of you who run a Corrado at weekends only or a couple of times a month may think about the check. Not seen it occur like this on daily drivers, probably something to do with the hoses being regularly flexed by the brake pressure, so the rubber doesn’t deteriorate.

[dinkus 10]

Ah well worth taking a look at, thanks for the pics RW1.

[RW1 0]

Goodridge hoses, you should be OK. I'll be thinking about this next time as even the replacement rubber ones on the C have started to go.

 

The C , replacement hoses now 2 year old, have blotted their copy book with the front left. The fluid was clear in the other three lines, the front left wasn't, it was mid straw brown when flushed / bled 8 weeks ago. Closer inspection showed the hose had a wet patch! Doh. It's under repeat inspection due this weekend after finding 4 weeks ago. Any hint and its OFF!

 

Hence my comment earlier about the 18 months old brake fluid in the photo earlier in this thread. Track days could also be an influence, that hasn't written by the owner on the use of the C the fluid came from.

[dinkus 10]

I don't have much choice, as I've got Mk4 callipers on the rear and 288 fronts, both of which need adapter hoses that only come as braided. So I figured I might as well go for a full set and got the mid hoses done too.

 

Should make for some nice firm pedal action though :D