WillyC4S

I know this is a much discussed about topic after doing an archive search, but I didn't find a consistent process to insure a 100% clutch bleed.

I'm looking for a method that I can use that will not leave any guess work and will result in the clutch being fully bled. I've already bled the brakes and it was a piece of cake with the Motive power bleeder, but this clutch bleed is a different story ....

I've got a Motive Power bleeder and had issues with getting the clutch fully bled. My '86 951 has a working master and slave clutch before I started this bleeding process, now the clutch pedal just sits on the floor of the car.

The car is on ramps, so the front is obviously higher than the rear (I've read this may cause problems). The Motive bleeder is attached and pressurized to about 15PSI and the brake reservoir is full; Motive tank has ATE blue in it. The starter is removed and I've got a 7mm wrench on the bleed screw and plastic hose on the nipple.

The clutch pedal is up and I proceeded to unscrew the bleed valve until fluid changed blue; fluid did not have bubbles.

I tightened the screw and then climbed back out and checked the clutch pedal. It fell to the floor! I thought I was doing this right but obviously not!!

What did I do wrong?

Couple of questions:

1) Should clutch pedal be up when bleeding or down? Does it make a difference?

2) I've read that in manually bleeding the clutch (w/o pressure bleeder), one should make sure that the pedal is up before putting fluid in the brake reservoir. Is this needed in a power bleeder?

3) Is the fact that the vehicle is on ramps and the front is higher than the rear causing me problems? My guess is that somehow, even under 15PSI pressure, that the forward end of the reservoir is not getting enough fluid so is causing this condition. Any comments on this?

4) When using a pressure bleeder, is clutch pedal movement still necessary (i.e. have an assistant pump the clutch pedal) for a complete bleed?f

Thanks for all the help.

*****

Manning

Not trying to be a jerk, but are you sure the bleeder is sealed? I had trouble on my motorcycle a long time ago where one of the brake bleeder screws would not seal up and wound up replacing that screw. Maybe you aren't sealed up and your just pumping fluid out onto the floor.

Or maybe your master or slave is fried. Look up under the dash and see if you have a wet spot around where the master cylinder shaft comes through the fire wall. If so it has blown a seal. Check up under the car to see if the slave looks like it is leaking.

Matt Sheppard

*****

Your rear end must be higher than your front end to bleed the clutch. The resevoir for the clutch is in the forward compartment of the brake res. and is segregated by a dividing wall. It is also small and can go dry quickly if not fed fluid over the wall from the brake res. if the front is on ramps, i.e. really up there and the rear is on the ground, you could put fluid in the brake res. and it will never get to the clutch res. because of the wall and it's cocked back angle.

Motive bleeders are the bees-knees and will do the job better than anything but only when the cars attitude is correct- higher off the ground in the back.

WillyC4S

Michael,

The system was functioning correctly before I started bleeding it. The clutch slave was replaced about 4-5 months ago from what the records indicate.

Thanks,

*****

jim968

If you're just using the Motive as a pressure source (not filling it with fluid), you've likely sucked some air into the supply line & maybe the clutch master cylinder. You'll have to fully bleed in small increments, stopping to refill the reservoir. "Rocking" the reservoir will let you get more fluid in each time. This is especially true with the front end up. Dunno if the pedal up or down works best; up worked for me. You may now need to bleed the line where it exits the master, and where it goes into the slave, before bloody well bleeding the bloody bleeding bleeder.

If the pedal is a bit spongy (like a little air), try getting the back up on ramps later for another bleed.

Jim, bloody bleeding bleeder, indeed!

Phil Harrison

I struggled with this issue for a year or so, but think I have it licked now.

Firstly, make sure that the clutch pedal is adjusted to have free travel at rest. Haynes actually documents this quite well... I originally had the rod too long, when it was cold the fluid contracted & pulled the clutch pedal to the floor...

Then, the rear of the car must be higher than the front, it looks scary! I have the front wheels 6" off the floor & the rears 12" up. The reason for this is that the bleed valve end of the slave cylinderis lower than the engine end & the air can sit otherwise.

Once jacked up it's very easy to bleed.

p.s. Watch out your wrench doesn't hit the starter contacts BTDT.

WillyC4S

Thanks Phil, Jim and Matt on the responses. I'm re-thinking about the process I used and I think I may have drained down too much fluid from the front brake reservoir and let air into the system.

The rear-end above the front-end position would seem to be the key in making it work. Not only will the air bubbles flow out of the slave cylinder but the forward reservoir holding the fluid for the clutch system will be filled in this position. I'm going to try this soon.

Thanks for all the good info and I'll post results when I get time to try this again.

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951Tom

With a pressure bleeder you don't have to worry about having the *** end of the car in the air. The pressure will force out the air. I pressure bled my clutch hydralics fine with it level on 4 jack stands. If it was fine before, and you didn't re-adjust the nut at the top of the clutch pedal, then you still have air in there. Keep bleeding while depressing the clutch with your hand a few times while the bleeder is open. You may have to pull it up off the floor. Start with a resevoir filled to the brim. Also try and get the hose filled with fluid before you screw it on the resevoir.

newoldguy

With all due respect to the above posters, I didn't have any trouble with my car when the front end was higher than the rear. Also, I had the clutch pedal "up". I thought the Motive bleeder made a tough job easy. Good luck.

WillyC4S

Hello,

I just wanted to post a follow-up to my clutch bleeding adventures and what I finally ended up doing to get the clutch bled correctly. I didn't use the Motive power bleeder in the end and opted for the old-fashioned pump-the-clutch-pedal method.

I took a close look at the brake reservoir to determine which hose was leading to the clutch master cylinder. This is important since you don't want to have the brake fluid go under this level otherwise you'll be sucking air (literally). It turns out it's the large blue braided hose which goes from the driver's side of the brake reservoir to the clutch master cylinder. When you bleed, make sure there's plenty of fluid above this line.

My car's on ramps so I couldn't jack up the entire rear as recommended earlier. I decided to jack just the passenger side rear section, near the rear jack point in front of the rear wheel. Lifting up on the passenger side rear will allow more brake fluid to flow to the blue hose as well as ensure that the fluid from the brake section of the reservoir goes to the clutch section.

I ended up performing the clutch bleeding in the old-fashioned manual way with another person pumping the clutch pedal. I filled up the reservoir with the brake fluid and then pumped the clutch pedal to get some of the fluid in the system. The level dropped some after this initial clutch pumping. I then proceeded to get underneath the car and told my helper to keep pressure on the clutch pedal. I released the bleed nipple and tightened up the screw after a few seconds of fluid flow. Told my assistant to lift the clutch pedal by hand and then apply foot pressure again on the clutch pedal.

Repeated this about 3 times and then came back up to check the fluid in the reservoir. I had to fill up to ensure the level didn't drop below the blue hose. Went down again and repeated this about 3 more times.

These last few times I visually inspected the clutch release lever through the clutch inspection hole near the slave cylinder. I could clearly see that the plunger was being pushed out as pressure was applied to the clutch pedal. As I continued to bleed the valve, the plunger would sink backwards indicating I was releasing fluid from the system. This was a positive indication that the system was being bled correctly.

The manual bleeding method really allows a clear indication of whether the clutch pedal is working or not. This is something that the Motive power bleeder doesn't allow you to see since you're depending on positive pressure to push the fluid out instead of the actual master cylinder system pressure. Knowing that the clutch lever is actually working is powerful feedback that's absolutely crucial in getting this job done; that was one of the blind spots in using the power bleeder, you didn't know what was going on.

I'm really glad I'm over this small hurdle. Now I've just got to buy a used starter motor since I cracked one of the mounting ears in the removal process because the steel bolt seized inside the aluminum mounting ear ..... it never seems to end.

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JonT

One thing I haven't seen mentioned here yet that worked for me...if you get it to the point where you have enough pedal resistance to drive the car at all, take it for a drive on a bumpy road and the pedal will firm up. I saw this advice here before and didn't really believe it but after three tries and about two liters of fluid I gave it a shot and presto, best pedal ever.
JonT 94 968 mit ATE super blue

Phil Harrison

[quote]Originally posted by Tom L.:
<strong>With a pressure bleeder you don't have to worry about having the *** end of the car in the air. The pressure will force out the air.</strong><hr></blockquote>

I use a pressure bleeder, but still found it critical to have the car's rear higher than the front.

Manning

Ooooooh, I get it. I was of the impression that you were using the Power Bleeder with extra fluid in its bottle, as if you were flushing the system. This method always seems safest as you never risk dropping the fluid level in the reservoir beyond a safe level. I hadn't realized you were only using it to pressurize the system and thereby introduced air into the lines.

Sorry, my bad.

By the way, if the slave had to be replaced, the master may not be far behind.

IceShark

JonT, that bumpy road idea is mine. I now again live in MN so there are plenty of freeze heaved roads around. I've been doing this trick since '91. <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

The other tricks are put grease on the slave bleeder nipple threads so air can't sneek back in and just pull the slave, tip it upright - bleeder screw top - and bleed. This works great without having the car at some frightening position with you under it. But be gentle so you don't fracture the supply hardline.

I wish I didn't know so much about how to bleed the 944/951 clutch. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

Phil Harrison

[quote]Originally posted by IceShark:
<strong>I wish I didn't know so much about how to bleed the 944/951 clutch. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" /> </strong><hr></blockquote>

Add me to that list.

While these cars hold awesome performance & look sharp there are a number of things that drive me nuts....

Changing the alternator requires removing half the induction system, draining the coolant & removing all the undertrays...

Changing the clutch requires removing the whole rear end!!!! <img src="graemlins/crying.gif" border="0" alt="[crying]" /> don't get me started...