Clutch bleeding problems

[Xcellr8]

Checked past posts on clutch bleeding, and found a few posts that touch on the problem, but not one that closed with details on a successful fix.

Using Motive Pressure bleeder, pumped to 20lbs, clutch pedal held nearly to the floor with baseball bat, open slave bleeder valve and not much fluid comes out, but pedal collapses completely to the floor. Pressure changes very little, if at all.

Pedal needs to be pulled up by hand. Then depressed again, held with bat, and open valve again, same results. A little fluid trickles out, pedal collapses, little change in pressure gauge.

With 20lbs pressure, I expected a steady and significant stream to pass through the bleeder valve when opened.

Any thoughts please.
Thanks,
Joe

[steved0x]

What was the condition of the bleed cap on the slave cylinder bleed screw? Mine was still there but it was very hard and totally fell apart as I was removing it. I didn't have one to replace it with so I left it uncovered, which gives the possibility of dirt or other contaminants getting in there and possibly blocking the flow the next time I do a bleed flush. (If your cap was in bad shape or missing maybe some dirt got in there?) But I heard you can shoot brake cleaner into the bleed screw and help to dissolve this when I do my next bleed/flush.

On my old Tacoma I did a bleed with the motive bleeder and I couldn't get any flow on one of the brake bleed screws, so I went in the cab and pushed the brake pedal while it was bleeding, and that extra force cleared the blockage.

Maybe you can shoot some brake cleaner into the bleed screw, hook up the motive and pressurize it, open the bleed screw, and have someone pump the clutch a few times to provide a little extra force and maybe clear the blockage?

When I did mine the stream was steady, but I wouldn't say it was significant by any stretch. It was slow and steady.

Steve

[san rensho]

Be sure the fluid reservoir is topped up. The orifice going the the clutch line is very high up on the reservoir, so you could just be pushing air.

[Xcellr8]

Thanks for the reply, but are you thinking the collapse of the clutch pedal is normal? I thought not. I expected the motive pressure to keep pressure in the system, and thus a firm pedal needing the bat to hold it down. With no motive pressure system connected, I would expect the pedal to collapse when the bleeder valve is opened.

So what good is the motive pressure, when it barely, pushes fluid through the system? And, is the condition of the pedal interrupting the pressure?

Thanks again, Joe

[Xcellr8]

Okay, I went with the assumption that the clutch pedal was doing what it was supposed to do and just continued with the bleeding process. Only this time, moved the wrench to open the bleeder valve more. As expected, the stream increased and the pressure started to drop on the Motive bleeder gauge. Now, this is what I expected. Drained about a pint through the slave cylinder, seeing no bubbles, decided to close the bleeder valve.

I'd say the clutch has been properly bled. Unless someone can convince me that the clutch pedal should not have collapsed to the floor and stayed that way during the bleeding process, I'm calling this normal and considering the bleed complete. That's the good news. The bad news is that it did not change the shifting - or rather lack of shifting.

I'm going to bring another thread to life to discuss that.

Thanks again for your input. Help on the other thread if you have any idea there.

Thanks,
Joe

[san rensho]

The clutch has to be on the floor to bleed. I just open the bleeder, push on the clutch and clutch stays to the floor. then I attach the power bleeder and bleed. A pint is way too much. A couple of ounces is all it takes to bleed the slave.

[steved0x]

Same experience with me, my son held the clutch to the floor, but as soon as I started the bleed it stayed down by itself, and I had to pull it up by hand after it was over. Totally normal.

Pedro has a good tutorial on it as well on his site and it documents that same issue:

Bleed the Brakes & Clutch

Steve

PS good for you, that clutch slave cylinder bleed screw is a !@#$%^ to get to, at least it was for me

[Gilles]

Originally Posted by san rensho

The clutch has to be on the floor to bleed. I just open the bleeder, push on the clutch and clutch stays to the floor. then I attach the power bleeder and bleed. A pint is way too much. A couple of ounces is all it takes to bleed the slave.

If I remember correctly, the shop manual calls to leave the bleeder open for 15-20 seconds at 20+ psi...

Needles to say, you will flush a lot more than a couple of ounces... (you may want a helper to keep an eye on the power bleeder fluid level)

.

[jsceash]

Originally Posted by san rensho

The clutch has to be on the floor to bleed. I just open the bleeder, push on the clutch and clutch stays to the floor. then I attach the power bleeder and bleed. A pint is way too much. A couple of ounces is all it takes to bleed the slave.

I disagree with this. you can bleed the clutch by just taking off the reservoir cap putting on a piece of tube long enough the clear the trans cover plate on the bleeder nipple and opening the bleeder on the clutch slave cylinder two hole turns take about 6 to 10 minutes to clear air and get about 2 to 3 tablespoons of fluid out. I found this out the hard way while replacing the clutch the first time several years ago. I disconnected the tube to the slave cylinder had the transmission out on the floor, then went in and ate supper. I returned after about an hour and a half the reservoir empty on the floor of my garage. When I install the tranny again this is how I bled out the air, no tools no pumping pedal up.

I now use a vacuum bleeder pulling several ounces of fluid at a time with no other steps while flushing or replacing the fluid. I bleed the system allot, and have never touched a pedal until finished. I use a vacuum tool, and thin tube adaptor and suck all the fluid I can from the reservoir. I refill the reservoir usually with another color fluid. I brake open the rear inside bleeder of the passenger side draw fluid until the color changes. Top off reservoir, go to outside port repeat, top off again. Then repeat on the drivers side. Then the clutch. Front Passenger side then driver side. I do this with the car on a lift without removing a tire in most cases and it take 45 to 60 minutes, and 1 liter of fluid. No pumping no pedal in a special position. I had early on put Teflon sealing tape on all the threads on all the bleeder nipples to improve the seal. Careful not to get it on the tapered end of the nipple.

[JFP in PA]

Originally Posted by jsceash

I disagree with this. you can bleed the clutch by just taking off the reservoir cap putting on a piece of tube long enough the clear the trans cover plate on the bleeder nipple and opening the bleeder on the clutch slave cylinder two hole turns take about 6 to 10 minutes to clear air and get about 2 to 3 tablespoons of fluid out. I found this out the hard way while replacing the clutch the first time several years ago. I disconnected the tube to the slave cylinder had the transmission out on the floor, then went in and ate supper. I returned after about an hour and a half the reservoir empty on the floor of my garage. When I install the tranny again this is how I bled out the air, no tools no pumping pedal up.

I now use a vacuum bleeder pulling several ounces of fluid at a time with no other steps while flushing or replacing the fluid. I bleed the system allot, and have never touched a pedal until finished. I use a vacuum tool, and thin tube adaptor and suck all the fluid I can from the reservoir. I refill the reservoir usually with another color fluid. I brake open the rear inside bleeder of the passenger side draw fluid until the color changes. Top off reservoir, go to outside port repeat, top off again. Then repeat on the drivers side. Then the clutch. Front Passenger side then driver side. I do this with the car on a lift without removing a tire in most cases and it take 45 to 60 minutes, and 1 liter of fluid. No pumping no pedal in a special position. I had early on put Teflon sealing tape on all the threads on all the bleeder nipples to improve the seal. Careful not to get it on the tapered end of the nipple.

The recommended method is to use a power bleeder and bleed the clutch with the pedal on the floor. If the pedal is not down during the entire procedure, the system is not fully flushed.

[watsongrg]

Here are some good tips and insight to clutch bleeding with a pressure bleeder.
-The area in the brake fluid reservoir, for the clutch, is small and partitioned. ie, the fluid for the clutch circuit is small and will empty quickly during flushing, unless a head of FLUID pressure is used via the power bleeder.
-depressing the clutch pedal to the floor will open the curcuit and fluid will flow FAST. ...(yet the reservoir will still show 3/4 full because you are looking at the level markings for the brakes partition)
.....So fast that the curcuit will empty and pull air, if you are being cute and using your power bleeder for just air pressure (not filling it with fluid, as some people do for brake bleeding).
If you follow the Porsche service manual procedure and open the bleeder for the slave cylinder and gently push the clutch pedal to the floor, 32oz. of fluid will flow in just over a minute.
This could be why people are have trouble with proceed, its using more fluid than they expect.

unless you are bleeding a new install, just bleed the clutch without depressing the pedal. It still flows fast and you need Fluid pressure from your power bleeder and plenty of fluid.

If you ever get into a bind and vacuum the clutch pedal to the floor and it wont come back up,
you can actually backfill the clutch curcuit from a brake caliper. Attach a length of bleed hose from your left rear brake caliper bleeder to the clutch slave bleeder. Open slave bleeder then the caliper bleeder and start gently pumping the brake pedal. This will backfill the system and raise the clutch pedal. you can do this as long as you want, its a closed cucuit sending air and fuild right back to the reservoir. So should have the reservoir cap off. Its genius and it works.
For a front wheel drive car with clutch bleeder up front, use the front left brake caliper.