Changing brake fluid without bleeding

Unless you're working on an ancient Mini or something similar I'd just bleed them normally. Bleed nipples aren't that fragile and if you use a decent spanner and don't pull down on it when you're turning it you'll be ok. Give them a spray with penetrating oil an hour before if you're still nervous.

Si

It doesn't circulate so it will never get to the wheel cylinders. The wheel cylinders are where the heat will boil old brown/black water contaminated brake fluid rendering the brakes useless. So what you propose is pointless unless you are doing this to defraud a buyer that the car has been serviced.

brian doyle ( snipped-for-privacy@yahoo.co.uk) gurgled happily, sounding much like they were saying :

Apart from the fact that the bit that remains unchanged is the bit that's actually doing the work...

Not sure how this will work.

The important bit of the fluid is the stuff in the calipers/cylinders.

Just changing the fluid in the reservoir will just mean that the fluid in the reservoir is changed. Unless you drain the fluid from the pipes, it's not going to go anywhere.

Pete.

Yeah, just the one: BWAHAHAHAHAHAHAHAHAHAHAHA.

Peter

-- "The humble bic biro draws 13 beards, 9 devil moustaches and 49 penises on newspapers in its lifetime."

You sure about that? I just tried what I proposed and replaced around 100 mls of fluid in the reservoir and gave it a good mix. This made the fluid in the reservoir notciably lighter. So then I drove the car and applied the brakes a few times and looked at the reservoir again and the fluid had definitely darkened again - not as dark as it had been originally but certainly darker implying that some old fluid from the lines had made its way into the reservoir.

brian

It would help if you retracted the caliper pistons first - if the pads are worn they could contain as much fluid as the reservoir.

One of those kitchen spray thingies is handy for removing brake fluid from the reservoir - simply pump it into a suitable receptacle.

I think you'd be unlucky to break a bleed nipple. Has only happened to me once in many years of working on brakes - and that on a pretty old car. I'll usually use a socket to undo them taking care to keep it square.

but you are missing the point the fluid that's in the calipers isn't going to magically travel back up to the reservoir to swap places with the fluid that's just been put in is it just flush the fluid through like you would normally until you see clean fluid coming out of the nipple this way you will use more than the recommended fluid capacity (because some of it is going to go to waste) but at least you know you'll have done it right

Just do the job properly - this is just faffing around. If you're worried about bleed nipples buy some new ones before starting the job.

Dave Plowman (News) ( snipped-for-privacy@davenoise.co.uk) gurgled happily, sounding much like they were saying :

Usually one that's not had the bleed nipples opened for years...

Totally and utterly pointless.

Don't mess about when it comes to brakes, take it to a garage.

And you really think some semi-skilled fitter is going to take as much care as you'd do yourself with something this safety critical?

Dream on...

The message from "Mungo \"two sheds\" Toadfoot" contains these words:

Deep sockets with a T-bar are good for this.

The message from "brian doyle" contains these words:

It'd take years to mix even the first few feet of pipe.

The message from "SimonJ" contains these words:

In his case that sounds reasonable - but most of us are capable.

Sounds like more work that doing it properley! Make sure you use a close-fitting socket over the nipple (preferably a six-pointed one) and you should be fine.

Darren

Brian

There is NO return pipe to the master cylinder. Therefore it is impossible for the brake fluid to return from the callipers or pistons without some sort of pressurised assistance.

If you empty the master cylinder, and then retract the callipers and pistons, you will push fluid from these into the cylinder and this can then be removed allowing you to add a small quantity of new fluid. But there will still be a lot left in the pipes - along with all the bits of crud that accumulates over the years because of water contamination.

Just one question though - is it worth risking your life (or someone else's) just to save time and a few pounds? Do it properly.

Brian G

OK, take it to a decent garage.

The message from Colin Stamp contains these words:

Does seem a lot easier. Of course - the bleed nipple is at the top of caliper - the sludgy water collects at the bottom.