Where is the clutch bleed screw?
 

I did a search and found various ideas on bleeding the clutch system, but I can't find the actual bleed screw on my 240D or any discussion about its location. I feel a little stupid for asking about it, but I just can't find it! I've bled brakes before, but only on automatics.

There is a bleed screw on the slave cylinder. It is located on the bell housing on the passanger side above midline of the bell housing. Ther eis also a bleed screw on the cylinder located at the clutch pedal.

The MBZ manual is as follows.

Bleeding by means of the Brake System

Bleeding of the fluid cioupling actuating system by means of the brake system is in principle the same as when a bleeding device is used - but with the difference that no special aids are needed. All that is needed is a piece of hose (transparent if possible) about 1 meter long. Bleeding is then carried out as follows:

1.

Sorry I have fat fingers.

"1. Check brake fluid level in brake resevoir and, in necessary, top up to maximum level.

draw the brake fluid for fluid coupling (slave cyliner) from the resevoir.

2. attach hose to bleed screw of right front caliper and open bleed screw.

3. Have someone else cautiously depress the brake pedal until the hose has filled with brake fluid and there are no more air bubbles to be seen. Prevent fluid from running out of the hose by nipping it.

4. Attach free end of hose to the bleed screw on the extraction cylinder and open bleed screw.

5. By alternately depressing the brake pedal and closing the bleed screw of the brake caliper, releasing the brake pedal and opening the bleed screw a number of times, fill the coupling resevoir to the maximum level.

Note; It is recommended to top up the fluid level in thebrake fluid resevoir once during the procedure.

6. Close bleed screws on brake caliper and extraction cylinder and disconnect the hose.

7. Check the coupling actuating mechanism for the function and leaks by hifting into reverse gear with engine running.

8. Top up brake fluid in resevoir to maximum level."

In summary, what the manual is saying is to first empty the clutch hydraulic system completely. Then back fill the system from the bottom until the resevoir is filled. They suggest using the brake system as a means of doing this. I suppose you could also use a conainer elevated above the car a couple of feet, and use hydrostatic pressure to back fill the system.

Good look

henry

Ok, here's another stupid question. What's the bell housing? I have the Haynes manual, and will probably follow their clutch slave cylinder bleeding method 1 since I have a power bleeder (it's the reverse flush method). I know there are other methods too, but there's no need to get into that, I'm just trying to find the slave cylinder and its bleed screw. BTW, your post seems to be incomplete.

Edit: Never mind. Your 2nd post came when I was typing this. Thanks for the procedure, though like I said I have a power bleeder which I'm sure will be easier to use than your procedure.

Slave cylinder, and I heard it's hard to get the whole air bubble out when bleeding. The bellhousing is the rounded case around the transmission, and the slave is mounted on the passenger side near the top on mine.

240dnewbie, thanks a lot! Your picture helped a lot and I found the slave almost immediately. Before I read your post I didn't know what bell housing was, but if somebody had told me "the passenger side of the transmission" I would have known exactly where to look.

I have the Motive power bleeder and today was the first time I used it and it's awesome! Brake bleeding is actually kind of fun now. :) I didn't use the reverse flush method on the clutch system and instead I just bled it like the brakes... no bubbles and clean fluid and clutch still works great afterward.:cool:

HGV gives a good explanation of proper bleeding, however, if you have the time, you can just bleed it like brakes, two man method, then let it set overnight. The remaining bubbles will work themselves up and into the reservoir.

Good luck,

Can someone help explain this to me in plain words? I need to bleed out my clutch system, but my main problem when reading this description is that I don't know what a few of the words referred to are.

I put Henry's post in blue and my questions in black.


"1. Check brake fluid level in brake resevoir and, in necessary, top up to maximum level.

draw the brake fluid for fluid coupling (slave cyliner) from the resevoir.

^^Is the above statement just a summary of what is about to follow?^^

2. attach hose to bleed screw of right front caliper and open bleed screw.

3. Have someone else cautiously depress the brake pedal until the hose has filled with brake fluid and there are no more air bubbles to be seen. Prevent fluid from running out of the hose by nipping it.

4. Attach free end of hose to the bleed screw on the extraction cylinder and open bleed screw.

What are they referring to by "extraction cylinder?" Is it just the clutch slave cyl?

5. By alternately depressing the brake pedal and closing the bleed screw of the brake caliper, releasing the brake pedal and opening the bleed screw a number of times, fill the coupling resevoir to the maximum level.

Note; It is recommended to top up the fluid level in thebrake fluid resevoir once during the procedure.

Again, this is confusing because I don't know what the coupling reservoir is. Is it just a container to drain fluid into, is it the slave cyl etc?

6. Close bleed screws on brake caliper and extraction cylinder and disconnect the hose.

(Same confusion continues - don't know what extraction cylinder is)

7. Check the coupling actuating mechanism for the function and leaks by shifting into reverse gear with engine running.

8. Top up brake fluid in resevoir to maximum level."

In summary, what the manual is saying is to first empty the clutch hydraulic system completely.

Where do you empty it into?

Then back fill the system from the bottom until the resevoir is filled.

Is the fluid sucked back in by means of the break hydraulic system by opening up the bleeder on the caliper, releasing the brakes, closing nipple, pressing breaks, etc....?

They suggest using the brake system as a means of doing this. I suppose you could also use a conainer elevated above the car a couple of feet, and use hydrostatic pressure to back fill the system.

Ok, so if you read all this you probably get the idea that basically I need to know the meaning of a couple words and that would probably clear up a lot of things. Any other advice would be appreciated as well.

Thanks

Just spend $45 on a cheap pressure bleader and make your life a lot easier. Pressurize system, open bleed screw and you're done.

Scott

I would consider that. How would I do this procedure using a pressure bleeder? Ie: hook what up where and do what till when?

You can buy one here: http://www.amazon.com/Brake-Bleeder-European-PBE100/dp/B000U08W96/ref=sr_1_1?ie=UTF8&s=automotive&qid=1228162616&sr=8-1 (Looks like they've gone up about $5).

You screw the cap onto your brake resevior, fill the thing up with fluid, pressurize it, then unscrew your brake caliper bleed screws, or slave cylinder bleed screw, and let the old fluid run out until the new fluid appears. Its a very handy tool.

Scott

Did not know that this thread was still around. I see that I must have cut and pasted from the manual. I will answer using the original numbers.

1. The clutch hydraulic system has two cylinders, the slave cylinder is located on the bell housing and the master cylinder is located under the dash attached to the clutch pedal. It has an independent reservoir. The brake system will be used to back bleed the clutch system. The clutch system needs to be drained of all the fluid first. Use a baster, suck out all the fluid from the clutch system reservoir. Be prepared to buy the kitchen a new one. I usually beg for forgiveness rather than asking for permission.

4. The "extraction cylinder" is the slave cylinder on the bell housing. I guess the cylinder extracts the pressure plate from contact.

5. This is confusing. I simpler words, the brake system will provide the fluid to back fill the clutch system. Using the front right caliper, attach a hose to the bleed screw brake caliper and the other end to the bleed screw of the slave cylinder on the bell housing.

6. As you pressure up the brake system, open the bleed screw on the brake caliper and push the fluid into the clutch system.

8. Suck out the clutch system reservoir, then open the bleed screws and drain the remaining fluid into your wedding china tea or coffee cup. A creamer will work also, or alternatively a gravy boat.

In summary, the brake system will push the fluid back into the clutch system. I would keep the slave cylinder bleed screw on the bell housing open and open and close the bleed screw on the caliper. Make sure that the bleed screw on the master cylinder under the dash board is closed.

Happy bleeding.
Henry

Thanks very much Henry for the clarifications and humor :D

Interesting. When I changed the slave cylinder on my 240D, I just worked the clutch pedal about 50 times and the system self-bled.

the easiest way I have found is the pressure bleed. I made one from a garden sprayer and a PNP brake res cap. The instructions are on this forum. with pressure on I pumped the clutch pedal 10-20 times and closed the bleed screw. I tried the back flow method first but it never worked because when I cracked open the bleed screw on the slave the pressure just leaked out the threads of the bleed screw.