New clutch hydraulics will not build up pressure.

[kountrymike]

My clutch master cylinder went out on my 1990 Accord. I followed the video on how to replace the hydraulics and I replaced both the master and the slave. When I went to bleed the system it will not build up pressure. I tried gravity bleeding and leaving the pedal to the floor to let any air come out the reservoir. I even tried the wife which she did a good job and it still did’nt work. I am starting to think the new master cylinder is bad. I have checked all the fittings for leaks and nothing has shown signs of wetness. Is there something I am missing? Can turning the shaft that attaches to pedal mess up the insides of the pump? I am at a loss right now please help.

Thanks Kountrymike.

Topic

[619DioFan]

Did you bench bleed the master prior to installing it ? if not I would remove it and bench bleed it first , then reinstall. bleed the slave cyl as you would a caliper or wheel cyl. I don’t pump the pedal but push it down slowly as the bleed screw is cracked open. I don’t think adjusting the push rod would damage the master. have someone push down on the pedal, watch for air bubbles in the master. it is possible to have recieved a defective part.

[William McClurg]

I just did the same thing with my 93 accord. What ended up working the best for me was leaving a small pair of vice grips on the bleed screw, then getting some spare vacuum tubing to go over the tip of the bleed screw on the slave cylinder. (My parts store gave me a short section) then get some clear aquarium tubing (Walmart) and force it into the vacuum line that is attached to the bleed screw nipple. Fit the plastic tubing through a hole you drill in the cap of a clear plastic bottle that has some clean brake fluid in it (Note: I am only recommending brake fluid because it is what is recommended for my ’93 accord clutch) Eric has shown this device in one of his videos. (College Man, can you help me out, I’m typing on my phone) I found it helpful to put another hole near the top of the bottle to release pressure because the tubing sealed the bottle completely, which made bleeding impossible.

With your left hand holding the vacuum tubing FIRMLY in place (the nipple of the bleed screw on my slave cylinder was dreadfully short) keep your right hand on the vice grips locked onto the bleed screw nut. Remember to open the screw then press the clutch pedal down, then tighten the screw and pull the pedal back up. Think out with the old, in with the new!

If you are not getting resistance and rebound on your clutch, then it has likely not been bled sufficiently. Use this as an opportunity to bleed all the old, contaminated clutch fluid out of your hydraulic system. Really go overboard with it. You’ll be happier with the end results if you do.

As far as a bad master cylinder, I would be surprised, but I suppose that you do get what you pay for. I would replace the slave cylinder as well. The master is aluminum, but the slave is cast iron. My slave cylinder was roached completely, and my master had only just started to leak. If you have noticed squeaking while actuating your clutch, this is likely the slave cylinder squeaking in the cup of the clutch fork. I ordered my parts from Beck Arnley, which was one of the more expensive parts out there, but I’ll put another 250,000 miles on my car, hopefully.

As far as bench bleeding, it really is not necessary on our model of car given the small size of the hydraulic system. I didn’t when I replaced mine, and the bleed process in situ took about 5-10 minutes.

As far as turning the clutch adjustment shaft doing damage to your master cylinder, I think that is highly unlikely. Just make sure you have the clutch cylinder length as suggested in Eric’s video.

Also, you sound like you are learning about this process the same as I am so I will tell you that there is no clutch “pump” to have damaged other than your left leg. The system is straight hydraulic with no booster anywhere. Normally, with a hydraulic clutch you have a large master cylinder with a fairly short piston travel attached high up on the clutch pedal arm. Then you have a small slave cylinder with a narrow cylinder attached to the clutch fork. This gives you a significant mechanical advantage in actuating your clutch (think fat kid on a seesaw). In our car, the MC is only slightly larger than the slave cylinder which begs the question, why not a cable clutch?!? Perhaps someone else could elaborate???

Good luck, let us know if you have any more questions. Be sure to let us know how it turns out!

Will

[college man]

as suggested remove the master and bench bleed.
if no luck.then part is defective and another is
needed.

[kountrymike]

I went ahead and did a bench bleed while in the car. Also I pumped 3-4 times between bleeds and wa la it worked. Thanks for yalls help. I will stay dirty cleaning up my giant mess I made. banana:

[619DioFan]

Glad you got it worked out. thank you for posting the results.

[college man]

Thanks for the update. 🙂

[EricTheCarGuy]

Yes, thanks for the update. I have run into this from time to time and it’s normally the result of the parts that were used. That said I’ve found the best way to deal with it is to use a vacuum bleeder as that’s been the most effective method for me in the past.

Thanks for keeping us up to date and for using the ETCG forum.

[Rich]

Flushing the fluid on a clutch after attempting to fix a squeaky slave cylinder, I ran into exactly the same problem and fixed it. Here’s how.

First the symptoms. I pushed the clutch pedal down. It stayed down. i pulled the pedal up, then pushed down. The pedal stayed down. Repeated 20 times and still no clutch pressure. After a dozen or so iterations, there was still nothing draining from the bleeder. No sign whatsovevr of any built up pressure being released.

I then opened the bleeder valve with the pedal down, but no fluid flowed. I even removed the bleeder valve entirely and it was bone dry. No sign of fluid flowing at all from the bleeder.

All of this was done with a piece of tubing attached to the he bleeder outlet as described in multiple sources including the service manual. The tubing drained into a bottle with 1cm new fluid. The bleeder valve was only opened with the clutch pedal fully pressed down, and the resevoir open.

The solution involved pulling the pedal back up and cracking the fluid _inlet_. Almost immediately, bubbles began forming. After removing the fluid inlet line (flowing from the master cylinder) entirely, fluid was draining from the reservoir copiously.

Then I reattached the inlet line. I pumped the clutch pedal again, and suddenly pressure.

I believe that a large volume of air had entered the line, preventing the movement of fluid into the bleeder. Opening the inlet and allowing fluid to drain purged enough air so that the line could begin operating properly again.

I searched all over to find a fix and found nothing. It’s an amazingly widespread problem that plagues a variety of makes and models. As afar as I know, the solution I described has never been published. In fact, this was one of the most difficult parts – in only a few cases did anybody follow up with what resolved the problem. And in those cases, major work, towing. and parts replacement was involved.

This solution – disconnecting the fluid inlet and letting it drain for a bit, then reconnecting – got me on my way without any more hassle. I was able to fully bleed the old fluid with no air bubbles emerging, and the standard pump-the-pedal-and-bleed method worked just fine.

Eric, if you’re reading, this topic could really use a video.

[Author]

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