ZPmadA

I am replacing the hose that runs from the master to slave cylinder. My original hose broke. I assume I have to bleed the system through the slave cylinder (I won't be replacing). From what I read on clarks garage, there is a bleed line attached to the slave cylinder? Is this true? The slave cylinder has a bleed line out of the factory? This needs to be placed in a clear jar of brake fluid to see when the bubbles stop? It doesn't list a "pressure bleeder" as required equipment. I'm trying to figure out if I need to pick one up on my way back from work. What size hose diameter?
Finally, could/should I bleed my brakes after bleeding the clutch? I want to do the clutch first to make sure it works fine before starting something else.

JohnKoaWood

Pressure bleeder is the easiest, quickest way, but some have had success with reverse bleeding..

There is a bleeder nipple on the slave, attatch a piece of hose over the nipple to make it a much cleaner job, not needed if reverse bleeding as you will be pumping fluid IN through the bleeder..

I bleed my brakes, and do a full fluid swap any time I open any of the hydraulics, but I am **** like that...

RobE952

Bleeding the clutch is a serious PITA! I've had the pleasure of doing it 3 or 4 times now and it has not become any easier or faster.

I've never tried a power bleeder, but wish I had one. I've tried a vacuum pump on the slave cylinder with poor results. All 3 times I have resorted to a 2-man operation; one guy pumps the pedal while the other operates the bleed nipple. The "pumper" says when he is starting and finishing the pump motion so that the "bleeder" can open the nipple and close it before the pumper pulls the pedal back up (sucking fluid from the reservoir, not the slave cylinder). I believe this technique (or something similar) is mentioned in Clarkes garage. I've done it with the starter installed, but it would be easier without.

It will seem like you are getting nowhere for the longest time, only small drips of fluid with each pump. Then all of a sudden you will get big squirts of bubbly fluid which will eventually turn clear. Check the stroke of the clutch actuator and adjust the pedal for the right amount of free play, and voila!

Make sure you keep the reservoir topped up at all times and buy a large bottle of fluid, you will go through more than you think. Also, I can't remember exactly but I think a 3/8" tube will fit the bleeder.

gruhsy

Rob if you do it again I have a power bleeder and it works awesome. Did my brakes and clutch in about 20 minutes and I wasn't working hard at it either.

Bought mine from LR and money well spent.

Jason

Ronin-951

There is a basic design flaw in the system, the hard pipe connecting the Master to Slave is the highest part of the system and air will accumulate in that pipe. The pipe is horizontail at that point and the air just sits in the top half as the fluid is pumped back and forth, never displacing the traped air. If you can get the fluid to flow fast enough, long enough, to carry the traped air along, success and a firm pedal. Real life, garage mechanic, not gonna happen. I got a $15 hand vac pump, useful for many tasks, and a 'Saddle Tap' valve to end that problem forever. Installed the self pierceing valve in the high line, connected hand pump, three pumps later, perfect. One man, about a minute.

ZPmadA

I have attached the new line to the slave cylinder and have a question. Is it nut suppose to be flush with the slave cylinder? I can't remember but this is as tight as it will go.

JohnKoaWood

Tight is good, doesn't sit flush...

RobE952

Argh! I was thinking of asking you but never did. I will definitely come see you when I bleed my brakes next spring.

Let's meet up when you get the 3.0L fired up. I'd love to see it.

Luis de Prat

+1.

I made my own, but a pressure bleeder is definitely the way to go to bleed the clutch slave hydraulics.


Go easy on the bleed nipple or it can round off. It takes a 7 or 8mm wrench, IIRC. Also, don't unscrew it too far out, or you'll have air entering the slave through the threads.


On the later 951 cars, there's a support bracket somewhere between the reservoir and the slave cylinder that is a major PITA to replace. I certainly don't want to ever do that again.

quinnfiske

"There is a basic design flaw in the system, the hard pipe connecting the Master to Slave is the highest part of the system and air will accumulate in that pipe. "

This is true. There is also a connection at that point, just in front of the firewall. I got the air out of mine by opening that connection and pulled fluid through the master cylinder with a Mity Vac hand pump. I put it back together and continued bleeding from below. Worked great for me. I have since bought a Motive Power Bleeder and will try that next time.

Luis de Prat

You will be quite pleased.

ZPmadA

I am thinking of funneling fluid through the top of the hose running to the slave cylinder (the connection is near the oil filler cap). Will this expedite the process or make things easier? Air will still be left in the horizontal hard line that runs to the reservoir.

quinnfiske

That is what I was refering to. Worked for me.

ZPmadA

" That is what I was refering to. Worked for me. "

quinnfiske - I have no idea how you did that. The hard line curves down to connect to the rubber hose that runs to the slave. When you used the hand pump to draw fluid up, how did you disconnect it to connect the rubber hose (threaded) without having the fluid pour out? (since it is a 90 degree angle downward)



Also, I don't understand how jacking up the rear of the car will help. The hard line is behind the reservoir so wouldn't you want to jack the front of the car up to raise the reservoir higher than the hardline?(allowing air to bubble into the reservoir)


I tried jacking the front and bleeding, no luck.

I tried bleeding with the car level and I had brake fluid pouring out the slave's bleed valve with no air. I closed it and the clutch pedal still doesn't return on it's own.

I'm going to try to jack the rear as high as possible with the front wheels on the ground, but I'm not sure how I'll get under there without jacking the front up. Can I safely have jack stands on the rear with the front wheels on the ground? The hand brake doesn't work the front wheels so I worry the car will roll off the jack stands and fall on me.

Luis de Prat

Seriously, use a pressure bleeder.

Here's how you can make your own:

http://www.bmw-m.net/TechProc/bleeder.htm