Bad clutch master cylinder? Or air in system? Or something else...
 

Hi guys, new to the forum. I've got an issue, done some searching but haven't found anything that addresses my specific problem, so here it is:

I just bought a 2004 Accord V6 with the 6-speed manual transmission. Over the course of a few days driving it, I've found that the clutch pedal gets soft and slow to return after being pressed during high-rev shifts (5000 rpm and above). This happens fairly regularly during these types of shifts; I can reproduce it pretty consistently. After this happens, I have to pump it once or twice before it will disengage the clutch again.

Seems like a pretty straight-forward leak in the system, most likely at the master cylinder. The weird part though is that when shifting and more normal rpms (4000 rpm and below), the clutch pedal behaves completely normally. When sitting at idle speeds, I can engage and disengage the clutch all day long, and I can hold the pedal indefinitely at various positions without it losing pressure or failing to return quickly.

Has anyone else experienced something like this? What about high-rev shifts would cause this to happen, and why would it work find during normal shifts? The only idea I had was the possibility of some air trapped in the system that works its way back to the master cylinder during higher acceleration. Seems like a long shot though.

From reading other master cylinder-related posts, it sounds like the first step is to check the clutch hydraulic system for leaks, then bleed it. Is the master cylinder tough to replace on the v-6 6-speed? I've found some guides online, but I think they're referring to the 5-speed on a 4-cyl.

Thanks for your help!

In the picture below the slave cylinder is #9. Looks like it's between the transmission & the radiator, kinda like the 4-cyl.
http://www.hondaautomotiveparts.com/...dn01_b2320.png

Like you said, look for leaks then bleed it. The parts might not be interchangable with the other engines, but the idea is exactly the same.

Thanks for the diagram, very helpful. I checked the fluid level this morning, not quite at the "low" mark, but close enough to make me suspicious. Wasn't able to check for leaks very well in the dark, I'm going to check more thoroughly this afternoon.

I would bleed them

1- to make sure no air is in the line

2 - to get new fluid in the system and get rid of the old fluid


I have a simple way of bleeding almost anything by myself

go buy about 6 feet of clear tubing that will fit in the bleeder on the slave. Around 1/4" diameter - I buy it at the home improvement store

Then loosen the bleeder just a little bit (1/2 turn) with the hose on the bleeder already.

I then hang the loose end of the hose up to the hood and poke it into one of the many holes under the hood.

So now you have the hose dangling from the open hood and connected to the bleeder.

Make sure the master is full of fresh fluid

now go slowly pump the clutch, you will see nasty brown fluid filling the hose.

After a few pumps get out and check the master, add fluid if necessary, pump a few more times, then close the bleeder valve - you are done.

Air is gone and lines are full of new fluid.

Couple other pointers...
Not sure about the V6, but other Hondas I've done, the clutch pedal will stick to the floor when you're bleeding it. So before you start, wrap some cord around the pedal so you can pull it back up. But control it with your foot - DON'T let it snap upwards, that seems to suck air into the master.

And of course, don't pump fluid out of the hose & make a mess of your hood. That fluid eats paint. Have some way to drain it, then pump some more until it's clear & clean.

Might see if your local parts store has the correct size "speed bleeder" for the slave...it is a bleeder that will allow fluid out but not let air in.....makes things soooo much easier, just my two cents.

clutch sticking down to the floor also..
 

I am new here and have not had a Honda since my 95 integra GSR was stolen about 7 years ago.. I am having the same problem though, if I hold the clutch down for a minute or so (like at a light) it will most likely stick down about halfway, and then as I put the shifter back in neutral and ease up on the pedal, it will almost POP back up from the halfway point and be pumped back up to normal and work fine. I'm really automotive savvy and have had a bunch of fun cars from GSR'S to GSX'S TO SRT-4'S. ... and I've never seen anything g even remotely close to this. Please help me out here guys, I'm back in VTEC with an 05 accord coupe with the 6 speed and the j30A5 and I'm in love, but I'm lost here thanks in advance for helping the new guy

Suspect a leak (external or internal) in slave cylinder or master cylinder or both, allowing fluid level to leak down under pressure. When fluid level gets low enough air will be pulled into system and clutch will be ineffective.

If you're not losing any fluid, an internal leak in MC is likely allowing ipressurized fluid to bypass piston causing loss of clutch pressure. In this case no external leaks will be present.

Check slave and master for leaks and replace as indicated. It's not a bad idea to replace both at same time.

If no leaks, suggest replacing MC.

Read posting rules. It's not a good practice to post a new problem on an old thread, even when related.

good luck

So I am having the exact same problem you did Stevieg909 how did you resolve it? I'm a daily semi aggressive driver lol?

PopJ30A4, I was never able to come to a resolution. I spent hours reading and testing, and it really comes down to one of two options:

1) The master-slave system is malfunctioning, either with one of the cylinders bypassing internally or drawing air in.

2) The clutch is malfunctioning.

The first and easiest thing to do is bleed the clutch cylinder system; make sure there's no trapped air.

After that, I had a buddy rev the car up in neutral with the clutch engaged while I held my finger on the linkage between the slave cylinder and the transmission. I couldn't perceive any movement, but it would be much more accurate to do with a dial indicator if you have access to one. This isn't a perfect test, but I thought that if one of the cylinders was bad I might feel the linkage start to drift in after a few seconds.

Beyond that, you can throw parts at it and hope something fixes it. I'd start with the master/slave cylinders because they're going to be way cheaper. A few posts I found online said the problem didn't go away until they replaced the clutch. For me, I found that if I shifted at about 500 rpm below redline, the symptoms greatly decreased, and I couldn't justify the cost of a new master/slave system (let alone the clutch, which is ridiculous expensive on these things) given that everything worked just fine with the exception of this weird behavior at high rpm's.

Sorry, I know it's probably not the answer you were looking for. If you do end up figuring it out, post the answer up on here.