bleeding clutch actuator

[dougkirkbride]

finally got my brake and clutch lines run. brakes bleed. hard pedal yea! got clutch lines run and mounted to clutch actuator, reattached clutch pedal linkage, filled with fluid, but nothing. reservoir filled but wont go thru lines even with the bleed valve open. probably something i totally overlooked but i cant seem to get anything to get the fluid to flow. anyone else attempt to bleed clutch actuator with the unit off the transmission, dangling from the hose? dont see why that should matter.

I am pumping air, but fluid level is not dissipating in reservoir, maybe i have an air lock?

[Bob_n_Cincy]

finally got my brake and clutch lines run. brakes bleed. hard pedal yea! got clutch lines run and mounted to clutch actuator, reattached clutch pedal linkage, filled with fluid, but nothing. reservoir filled but wont go thru lines even with the bleed valve open. probably something i totally overlooked but i cant seem to get anything to get the fluid to flow. anyone else attempt to bleed clutch with the unit off the car, dangling from the hose?
Try adding some play in the clutch pedal linkage. The master cylinder piston must be all the way back before it lets fluid into the chamber.
Bob

[dougkirkbride]

Try adding some play in the clutch pedal linkage. The master cylinder piston must be all the way back before it lets fluid into the chamber.
Bob

Thanks Bob. I disconnected the linkage and actuated the rod/piston by hand. it seemed like it was bottoming out in both directions when i operated it by hand. walah i got some fluid to flow, very little/slow but movement is good. i need to go eat with the wife so i am going to need to come back to this later.

This forum is great for getting to resolutions of problems and it is great to have people like you "standing by" to give some advice or offer up some suggestions. it has also cost me some more $$$ in ideas and trinkets i have seen others do and has probably lengthened my build. :) oh well it's all fun.

[Goldwing]

I followed Wayne's suggestion of the pressure bleeder. I never dealt with the frozen issue, but others have had it. I wonder if the pressure thing helps prime the system better to avoid that issue and why I got lucky there? In leiu of a purchase, if you have an extra reservoir cap laying around, stick a schraeder valve on it and use a bike pump. I did something similar to look for boost leaks on my turbo VW. Good luck.

[K3LAG]

I had the same problem at first. Check the adjustment of the switches on the clutch pedal. They may not be allowing full travel of the pedal.

Larry

[ssssly]

Of note, Subaru clutch cylinders are notorious for being a PITA to bleed. The way that the hard lines twist around, traps all kinds of air bubbles. You can cut and make much shorter lines. The length and twists are for "pedal feel", not anything with function. Otherwise, just keep at it and eventually it will bleed out. Depending on where the bubble is I have bled clutches for 2 min, or 2 hours.

Another method I have used is to get a length of clear hose, I usually use fish tank air hose, and a cheap plastic syringe (can find them in the cooking section of any grocery).

Unbolt the slave cylinder and point the nipple up.
Put the hose on the nipple.
Fill the reservoir all the way up.
Then attach the syringe to the hose and crack the nipple and suck the clutch fluid through.
When the reservoir gets to half full, close the nipple, fill it up and repeat.

This will normally get you 80% there.

[Triathletedave]

Ok, I tried for several hours to bleed the clutch, with no success. I used a vacuum pump, but could not get any fluid to flow no matter how much vacuum pressure was applied. We later tried the vacuum pump attached directly to the master cylinder, and still could not get any fluid to flow. Shouldn't the fluid flow easily through the master cylinder if the clutch is fully out? Could there be a blockage in the master cylinder itself? Any ideas or suggestions would be helpful at this point.

As an aside, the clutch was smooth and worked well in the donor car. Can these things dry out or seize up if not used regularly?

Cheers,

Dave

[dagall]

If there is any air in it at all the clutch will not operate. Here is how I did mine on my 33. Got one of those old metal oil cans with a pump handle, attached a piece of clear hose to it. I attached the clear hose to the bleeder on the slave cylinder. Open the bleeder and slowly pump fluid into the bleeder from the can with the cap off the master cylinder. You should see and hear bubbles as your pushing the fluid from the bottom forcing the air and fluid up the system. May have to do it a couple times until all the air is out. Hope this helps.
http://www.bmpdesign.com/technical/bleed_clutch.php, Try this link as well.

[Bob_n_Cincy]

Ok, I tried for several hours to bleed the clutch, with no success. I used a vacuum pump, but could not get any fluid to flow no matter how much vacuum pressure was applied. We later tried the vacuum pump attached directly to the master cylinder, and still could not get any fluid to flow. Shouldn't the fluid flow easily through the master cylinder if the clutch is fully out? Could there be a blockage in the master cylinder itself? Any ideas or suggestions would be helpful at this point.

As an aside, the clutch was smooth and worked well in the donor car. Can these things dry out or seize up if not used regularly?

Cheers,

Dave

Dave,
Loosen up your clutch rod to add a little bit of free play to the pedal.
This allows fluid to enter the chamber.
Bob

[Triathletedave]

Thanks Bob. Should I be able to draw fluid past the master cylinder if I loosen the connecting rod? It seems strange that I cannot draw any fluid from the reservoir to the output line using a vacuum pump.

Cheers,

Dave

[Bob_n_Cincy]

Thanks Bob. Should I be able to draw fluid past the master cylinder if I loosen the connecting rod? It seems strange that I cannot draw any fluid from the reservoir to the output line using a vacuum pump.

Cheers,

Dave

Yes, When the rod is all the way out there is a fluid path between the reservoir and the main chamber.
This feature also make the system self adjusting as the clutch wears. Similar to disc brakes.
Bob

[Quiny]

Thanks Bob. Should I be able to draw fluid past the master cylinder if I loosen the connecting rod? It seems strange that I cannot draw any fluid from the reservoir to the output line using a vacuum pump.


Something seems wrong there, I used the cheap HF vacuum pump on the slave bleeder and was able to bleed it in minutes. I surprised your having so much trouble. In the past I have had to clamp the slave all the way back, bleed it then bleed it again with the clamp off.

[Triathletedave]

Something seems wrong there, I used the cheap HF vacuum pump on the slave bleeder and was able to bleed it in minutes. I surprised your having so much trouble. In the past I have had to clamp the slave all the way back, bleed it then bleed it again with the clamp off.

Ok, I loosened the connecting rod on the master cylinder, which did increase the range of movement slightly. I have even gone so far as to replace all of the hydraulic lines with new lines to be certain everything is airtight. I can now get vacuum pressure up to 600 lbs, but still no fluid will move through the lines. Any other suggestions? Do I need to replace the master cylinder?

Dave

[Bob_n_Cincy]

Ok, I loosened the connecting rod on the master cylinder, which did increase the range of movement slightly. I have even gone so far as to replace all of the hydraulic lines with new lines to be certain everything is airtight. I can now get vacuum pressure up to 600 lbs, but still no fluid will move through the lines. Any other suggestions? Do I need to replace the master cylinder?

Dave

Dave
Disconnect the line from the master cylinder.
Pump the pedal,
It should spit out fluid with each pump.
Bob

[Triathletedave]

Finally, SUCCESS!

I ended up watching a YouTube video that suggested 'locking out' the slave cylinder first before bleeding the rest of the system. It turns out that with such long lines (almost 13 feet in total) and moving parts in both the master and slave cylinders, it can be very hard to purge air trapped in the long lines if both cylinders are able to move at once. Bubbles just move back and forth inside the long lines.

I first disconnected the line from the master as Bob suggested, and verified that the master cylinder and connecting rod were set up and working as they should. I also replaced all of the lines with metric only lines and connectors to eliminate the supplied adapters. I was able to create better seals and ensure no leakage on any line connectors. Next, I removed the slave cylinder from the tranny and removed the rubber boot and rod. Then I put a small socket in the cylinder and fully compressed it with a large C clamp. This eliminated the moving parts at the rear. I then bled the system using the clutch pedal and rear bleed valve method (no vacuum system). It took about 12 sets of bleeds using the clutch pedal, but the fluid finally ran through the entire line and purged the air. I think I did a few extra sets to ensure that each bleed was fluid only - no air.

Only when I had a clean fluid bleed did I remove the C clamp from the slave cylinder. At that point I was able to replace the slave cylinder boot and rod and reinstall the slave cylinder. A few more slow compressions on the clutch and the slave piston moved out to its normal setting. A few more slow compressions and the clutch finally felt firm and both cylinders were working together smoothly.

It has been a bit of a nightmare, but with the help and suggestions of the folks here on the forum, I was able to solve the problem. Thanks everyone who responded! Now, back to the electrics...

Dave

[Buzz Skyline]

I bled my clutch three times yesterday (it's a long story, but mostly I don't like the way the manual says to run the clutch line under the intake). On the third round, I found an easy way to do it.

First, get a one-person bleeder kit (like this http://shop.advanceautoparts.com/p/autocraft-7-pc-one-man-brake-bleeder-ac558/9020969-P) whether you have a helper or not. They're cheap at most auto stores.

Fill it half way with fluid (DOT 3 brake fluid) and connect it to the clutch bleed nipple using a short line (mine was about 4 inches long). Disconnect the clutch linkage so you can pump it by hand (as others have noted, you don't get full range of motion with it attached to the pedal). As you pump the clutch, it will push out air and suck in fluid from the bottle. After you've pumped it a few times, go to the slave cylinder and pump the clutch fork to compress the rod into the cylinder to blow out any air trapped in the slave. Then pump master cylinder a few more times to make sure the fluid is clear of bubbles and you're done. It only took me a few minutes.

It helps to have someone watching for air in the fluid flowing through the tube to the bleeder bottle. My four-year-old daughter was the bubble spotter for me.

I tried other approaches (like this http://www.teamrip.com/how_to_properly_bleed_a_hydraulic_clutch_info.html ) but they were MUCH harder.