Intermittent clutch engagement issue

[JGood]

My car has been having an intermittent clutch engagement issue. Normally, it releases with the pedal near the top of it's travel. It feels great, no sponginess. Every so often, like this morning, I have to put the clutch to the floor, and even then, it barely is enough to shift, the clutch is still somewhat engaged. And it's spongy the whole way down. It feels like there is air in the line. Pumping the pedal for a while doesn't seem to help. I'll go out this afternoon to drive it home from work, and it will probably be fine, and release right near the top.

I have newer ATE super blue fluid, and the master and slave are only a few years old. But I'm not ruling either of them out as a potential problem. I just don't want to start throwing parts at it.

[JGood]

Today on my lunch break, I went for a test drive. At first, it was worse. I couldn't get it into first gear, the clutch wouldn't disengage, the pedal needed pushed in further. So I pumped it probably 100 times, and the pedal eventually gained it's full strength back. The clutch disengages right at the top of the travel, is stiff, and feels like everything is working perfectly.

So what would could cause a pedal to loose pressure like that, and not be able to gain it back regardless of how many times it's pumped, until a few hours later?

[Adrian_Visser]

I would tend to suspect the master cylinder wouldn't you? It isn't leaking any fluid though is it? That is kind of a weird thing to happen.

[JGood]

Yeah, I'm thinking the master cylinder could potentially be leaking back through the system. The pressurized fluid between the master and slave is pushing past the (worn?) seals of the master cylinder back into the non-pressurized feed line from the reservoir. It's just very strange that it works perfect sometimes, and only rarely acts up. Actually, this past winter, it did it every morning. It randomly started one day, and continued every morning. Then as it got warmer it gradually stopped doing it, and I forgot about it.

[jlevie]

That sounds like a bad master cylinder. At least that and a check for leaks in the lines and at the slave would be the place to start.

[JGood]

Great, I'll replace that for starters, and go from there. I visually inspected for leaks and didn't find anything. I'll do the master, and put fresh fluid in there and see what happens.

Does anyone have any experience with Autozone clutch master cylinders? They are about $50 and have a warranty. They are sold under the Duralast brand.

[Tree25]

Not personally with the master cylinder but with the brand I do. They suck really bad lol. I bought a duralast cap and rotor because the last 7 parts stores i checked didnt carry bosch. There is a price for convenience. Luckily it had a 2 year warranty but I was scratching my head when it ran even mor like dog shit. They only wanted to give me store credit. I eventually got cash after I explained in detail what a shitty product they carry. Seriously splurge a bit more and stick with OEM... You won't regret it.

[Tree25]

Woops resurrected an old post... me bad!

[JGood]

Not personally with the master cylinder but with the brand I do. They suck really bad lol. I bought a duralast cap and rotor because the last 7 parts stores i checked didnt carry bosch. There is a price for convenience. Luckily it had a 2 year warranty but I was scratching my head when it ran even mor like dog shit. They only wanted to give me store credit. I eventually got cash after I explained in detail what a shitty product they carry. Seriously splurge a bit more and stick with OEM... You won't regret it.

I don't even remember what I ended up doing as far as brand, but the master cylinder was the issue.

But regarding your cap and rotor story... I once bought a brand new Bosch cap, installed it, and the car ran like shit. After some messing with it, I found a hairline crack in the casing, and the spark was arcing out to one of the three mounting screws. The moral is, don't hate on the brand from one bad experience. Obviously Bosch is prefered over Duralast, but there's bad apples in every batch, and sometimes the cheaper part gets the job done just as well. I use $15 centric brake rotors on my track car with Hawk HT-10 pads, for instance. Works just as well as $50 Brembo rotors.