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Old 08-01-2011, 06:18 AM
 
Location: Baltimore
1,024 posts, read 1,995,229 times
Reputation: 1168

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Trying to troubleshoot an issue with pedal pressure. Seems like a hydraulics issue, although I took it to a mechanic for a second opinion and he said it is definetely the clutch (doesn't seem that way, but whatever). I hadn't been getting consistently good pressure from the pedal lately, so I bled the system (not by pumping the clutch pedal but instead, after breaking the bleeder on the slave cylinder, pushing the plunger that attaches to the shift fork, closing bleeder and releasing the plunger, repeating, etc.). I did this for a couple of cycles and refilled the fluid resevoir twice. BTW, the resevoir was full before I started, although the fluid was a nasty color.

Not much change, and I was also hearing a mysterious chirping sound with the engine running that would only go away when I pushed in the clutch. So I figured the next easiest thing to do would be to replace the slave cylinder. Did that, bled the system again, pedal pressure has gotten somewhat better (I don't have to pump the pedal as much to get pressure at least) but is still not consistent. Funny thing is, if I start from 1st and gun it in 2nd, I have almost no pedal pressure when I go to third. The pedal will engage almost at the floor. The chirp is gone, though...

My next assumption is the master cylinder, although I don't see any leaks. I kinda dread replacing it, because my car (2005 Accord) has the MC in a weird location behind the strut tower. I think it can be unbolted from inside the car but I don't know how the hell I will be able to access the hydraulic line to disconnect it. Any thoughts guys? Does it sound like poor pedal pressure or could this also be a sign of a bad clutch? Should I try to bleed it again, or maybe bleed it differently to get out any more air that could be trapped in there?
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Old 08-01-2011, 06:38 AM
 
Location: Central Texas
13,720 posts, read 25,457,746 times
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Remember that the clutch's natural position is engaged. The clutch pedal (and related hydraulics) move the clutch to a disengaged position. If you hear noise when the clutch is engaged and the car is moving, the hydraulics have nothing to do with it. That suggests your problem is with the clutch. Occasionally the slave will have a linkage problem (usually due to incorrect installation), which could cause the clutch to not engage/disengage correctly. But it still sounds like your clutch (or transmission) has a problem. Noise unique to a particular gear should have nothing to do with the clutch.
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Old 08-01-2011, 07:03 AM
 
Location: Baltimore
1,024 posts, read 1,995,229 times
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Quote:
Originally Posted by hoffdano View Post
Remember that the clutch's natural position is engaged. The clutch pedal (and related hydraulics) move the clutch to a disengaged position. If you hear noise when the clutch is engaged and the car is moving, the hydraulics have nothing to do with it. That suggests your problem is with the clutch. Occasionally the slave will have a linkage problem (usually due to incorrect installation), which could cause the clutch to not engage/disengage correctly. But it still sounds like your clutch (or transmission) has a problem. Noise unique to a particular gear should have nothing to do with the clutch.
I searched chirping sounds related to the slave cylinder and it seemed to be common. I replaced the slave cylinder and don't have that chirping sound (which only went away when I pushed the pedal in slightly before I cahnged the slave). Since I don't have that sound anymore, do you think this could still be related? I'm also sure I installed the slave correctly. I don't want to jump to assuming the clutch is going bad before the hydraulics are completely ruled out.

Last edited by Professor Griff; 08-01-2011 at 08:04 AM..
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Old 08-01-2011, 08:03 AM
 
Location: Baltimore
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Any other ideas?
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Old 08-01-2011, 10:17 AM
 
11,256 posts, read 43,182,783 times
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You mention the chirping sound when the clutch is engaged with the engine running ... which means that the input shaft of the transmission is turning at engine speed. At this point, the clutch and the T/O bearing, as well as the hydraulic system is out of the mechanical path of operation. And you mention that the sound goes away when the clutch pedal is depressed, which is when no further input is going to the transmission.

So, the chirping sound has to be originating in only one of two places:

1) the clutch hydraulics are holding the slave cylinder in light contact with the T/O bearing, so that's making a noise, or

2) the transmission has a failing bearing on the input shaft. BTW, have you checked the trans fluid level? and is it the correct fluid? IIRC, Honda has had some issues with the specific fluid needed in their transmissions; the OE stuff is the only lube that works long term.

Now, the lack of pedal pressure on repeated clutch actuation is a separate issue. I don't believe it's likely that the clutch is mechanically coming apart consistently on the 2nd or 3rd time it's actuated, so the pedal pressure has to be a hydraulic failure. I've not had good success with bleeding these systems as you describe, but have been able to do so only by pressure bleeding from the bottom up; absent having a pressure pot to do so, you could use a clean oil pressure can to pump hydraulic fluid up from the bleed port on the slave cylinder.

Keep in mind that a slave or master hydraulic cylinder can have an internal seep where the fluid by-passes internally, reducing the applied pressure ... and not have an external leak or loss of fluid from the system. At this point, it is possible that the clutch master cylinder is failing internally since you have now eliminated the slave cylinder.

As long as the clutch mechanically transmits the power from the engine to the transmission without slipping under load, and smoothly engages/disengages ... it's highly unlikely to be a failed clutch at fault.
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Old 08-01-2011, 12:37 PM
 
Location: Columbia, California
6,662 posts, read 26,208,561 times
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Quote:
Originally Posted by Professor Griff View Post
Trying to troubleshoot an issue with pedal pressure. Seems like a hydraulics issue, although I took it to a mechanic for a second opinion and he said it is definetely the clutch (doesn't seem that way, but whatever).
Be done by now if you trusted the mechanic's advice.

A mechanic would check the entire system where you are just guessing changing parts at whim.
The hose may be old and expanding, the throwout bearing may be worn.

Without putting it on a rack and looking all you will have is guesses.
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Old 08-01-2011, 01:12 PM
 
Location: Columbia NJ
24 posts, read 177,500 times
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Is it slipping? If the only problem is pedal pressure, do you have any visible leaks. You may have to get under the dash to see the master. Your bleed method is flawed and doesn't work well. If you have access to a mityvac, attach it and draw a vacuum. Have someone inside the car pump the pedal 10 times and hold it to the floor. Crack the bleeder. Repeat until pedal is good again. Use new dot 3 or 4 fluid. This should be done to clutch and brake hydraulics at least every 2 years.
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Old 08-01-2011, 02:52 PM
 
3,743 posts, read 11,280,055 times
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I'm assuming the car is at least a few years old with a good bit of miles on it, and yes, the clutch system needs to be fixed. It sounds like you have a symphony of behavior associated with needing the system reconned.
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Old 08-02-2011, 05:18 AM
 
Location: Baltimore
1,024 posts, read 1,995,229 times
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Quote:
Originally Posted by ferretkona View Post
Be done by now if you trusted the mechanic's advice.

A mechanic would check the entire system where you are just guessing changing parts at whim.
The hose may be old and expanding, the throwout bearing may be worn.

Without putting it on a rack and looking all you will have is guesses.
The mechanic I took it to did not check anything. He guessed after listening to my description. And no, I'm not just "changing parts at a whim". I'm trying to make logical assumptions. A mechanic who completely dismisses the hydraulic system and goes straight to labeling it a clutch problem is either trying to bleed money from me or is just not worth his shop. Either way, his guess was no better (probably worse) than mine.

My clutch isnt slipping. Yesterday and this morning I was getting decent pedal pressure but I noticed that if I apply very light and steady pressure to the pedal throughout its entire travel, I can ride it all the way to the floor. I can do this with the car on or off. I might re-bleed the system or have it pressure bled to ensure all the air is out, and go from there.
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Old 08-02-2011, 06:16 AM
 
Location: Baltimore
1,024 posts, read 1,995,229 times
Reputation: 1168
I'm leaning more towards the master cylinder. Coincidentally, there was a TSB out for my vehicle regarding the master cylinder. I had this replaced once before, and I believe it's the culprit again.
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