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Hi guys, I've changed front and rear pads today, fronts were done in no time but the rears had seized sliders so had to have the calipers off the car, when I bleed them is it best to by a power bleeder that connects to a spare wheel for pressure or just the old fashioned way? And can I just bleed the rears or will all 4 be needed

Did you let the fluid tank empty or did you clamp off the rear flexi hoses to stop fluid loss?

If the tank didn't empty then you should be able to bleed them the old fashioned way....my preferred method!

All i have ever used is the basic brake bleeding kit - non pressurised type.Basically consists of a clear flexi pipe with a sort of non return and a bottle.You probably only need to bleed back ones but you could do the fronts as well. Should do the backs first.

I used a pressure bleeder on my D9 no problem (apart from brake fluid paranoia). I reckon you should be able to get away with doing just the rears, unless the fluid's getting old in which case you may as well change the lot while you're at it.

Do not let the reservoir empty, if air gets into the abs block you'll rue the day...

I never got on with the one way valve bleeders, they seem to rely on the nipple being an air tight fit, which isn't always the case...

Good point, your probably right about the bleed nipples not bee an airtight seal when loosened.

For an air tight seal, Clamp pipe before starting, remove nipple and clean threads, wrap with a few layers of ptfe thread tape and refit. It also helps them come out again next time you need to remove them,

I wondered if PTFE tape would help, then I thought it might react with the brake fluid and maybe swell up, turning it into a comedy.

The threads on the nipple aren't the seal, the mating face at the bottom of the nipple is.

IMO I don't think it's wise to introduce a soft sealing tape in case it affects the proper sealing of the nipple. For ease of unscrewing later on I guess a tiny smear of graphite grease on the upper threads might be ok but perhaps someone more experienced like Jasper can advise on this?

Welly wrote:The threads on the nipple aren't the seal, the mating face at the bottom of the nipple is.

IMO I don't think it's wise to introduce a soft sealing tape in case it affects the proper sealing of the nipple. For ease of unscrewing later on I guess a tiny smear of graphite grease on the upper threads might be ok but perhaps someone more experienced like Jasper can advise on this?

The threads on the bleed screw have nothing at all to do with bleeding!

The fluid and air is forced out then you tighten the bleed screw...if some leaks out through the threads it doesn't matter as the important part is the brake cylinder or caliper...that is where you want the air to be removed from...you could still bleed the brakes even if the bleed screw wasn't there, as long as you keep the brake pedal fully depressed before fitting a bleed screw to lock off the cylinder/caliper.

When the nipple is loose air can enter via the threads, Dont put it on the taper that seals when the nipple is closed, It wont react with the fluid, Trust me I am an Engineer and I have been doing this for years, I use a mityvac for bleeding and changing brake fluid on Cars and bikes and putting tape on the threads stops air entering when sucking fluid through.

stevewalsh wrote:When the nipple is loose air can enter via the threads, Dont put it on the taper that seals when the nipple is closed, It wont react with the fluid, Trust me I am an Engineer and I have been doing this for years, I use a mityvac for bleeding and changing brake fluid on Cars and bikes and putting tape on the threads stops air entering when sucking fluid through.

In my 44 (almost 45) years of being a mechanic I've never had to seal up the threads on a bleed screw, it just isn't needed!
When you force the fluid/air out of the brake cylinder/caliper you purge the cylinder and unless you let the brake pedal up nothing can get back into the cylinder or caliper.The same applies using a pressure bleeder as once the fluid/air has passed out of the brake cylinder/caliper all you have to do is lock up the bleed screws.

I replaced an ABS control unit on a BMW Z4 just before Christmas....I bled the brakes on my own without using any pipes or pressure bleeder....after I had forcibly bled the brakes with the pedal pressed I left the bleed screw open until fluid dripped out...brake pedal released. The bleeding of the brakes took me 15 minutes.

Did them with a power bleeder that connects to the wheel valve and brake resivour took about 5 mins, peddle is good, brakes not so good but they will bed in soon enough, did it with engine on in case abs pump had air in too

My Mityvac uses vacuum to suck the fluid through, Without thread tape it also sucks through air via the threads, on the nipple. You do it your way I will do it mine.

stevewalsh wrote: You do it your way I will do it mine.

Of course

mundy1989 wrote:Did them with a power bleeder that connects to the wheel valve and brake resivour took about 5 mins, peddle is good, brakes not so good but they will bed in soon enough, did it with engine on in case abs pump had air in too

Well done