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I've read these posts but I still don't fully undestand how a clutch works.

Clutch Test

Clutch Adjust

Clutch Troubleshoot

Clutch Has Low Catch

A few weeks a go my mechanic replaced the clutch master and slave cylinder on my Toyota Tacoma 4x4. It drove fine for a week or so.

This morning after not driving it for 4 days, I cranked it, fully depressed the clutch pedal and could not get car in 1st gear. I let off brake, allowing truck to move slightly and then I could get in 1st gear. The gear fully engaged within first 3-4% of releasing the clutch, i.e. the clutch engaged immediately.

I drove to my first stop sign, depressed the clutch and applied brakes and came to a complete stop. After that I could not get vehicle in gear.

Somehow, I got vehicle in reverse to back in driveway. I depressed clutch, this time it behaved as if it were still in gear and would not stop. I applied brakes hard turned off ignition. With ignition off and foot off clutch pedal, stick shift moves between first and second gear with no resistance.

I want to have a full understanding of what happening so I can have an informed and intelligent discussion with my mechanic.

What's a likely diagnosis of my symptoms?

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1 Answer 1

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How does the pedal feel? Does it have the same resistance as normal, or does it feel really soft, and go straight to the floor?

If it it the latter, chances are you have air in the system, or a leak - check the fluid level in the reservoir (which should look similar to the brake one, but usually smaller).

If it feels normal, there could still be a small air bubble in the system - This is typically indicated by a small amount of free movement as the air is compressed, followed by a normal feel as fluid is pushed through, meaning that the mechanism works, but does not move far enough to release the clutch.

If it is normal through the entire travel, then I would suspect the mechanical release mechanism, i.e. the linkage between the slave cylinder and the clutch itself. I don't know the design of the Tacoma, but some cars feature a cross-shaft with a release arm attached with a grub screw or woodruff key, and these can break, allowing the shaft to rotate without releasing the clutch.

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The pedal feels limp and lifeless. When I depress it I get little resistance. When I slowly ease, just the first 1-5% feels like it engages any thing if at all. The remaining 95% of the release feels lifeless and limp. However, it does fully retract to original position when I release it. –  zundarz Sep 9 '11 at 15:08
    
Definitely air in the system then. If itdrove fine for a week or so then I would suspect either a leak in the system or a failed seal in one of the cylinders. If it's a leak or a failed slave cylinder, it should be obvious as the level in the reservoir should be low or empty. If the level appears to be normal then it is most likely a failed master cylinder seal. Make sure you check the clutch reservoid not the brake one, they usualyl look pretty similar! –  Nick C Sep 12 '11 at 8:57
    
..It was more than just a small air bubble in the system. The Master/Slave cylinder was defective and the mechanic replaced the entire unit. This solved the problem and the clutch works quite well. –  zundarz Sep 20 '11 at 15:23

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