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The Mystery of the Disengaging Clutch

HI everyone, I am looking for help. 2 years ago I had the transmission and clutch replaced on my 2002 Echo. it has driven fine since then but three days ago we were on the highway and the clutch suddenly disengaged…I don’t know if that’s the right terminology but it was as if I had pushed the clutch in (I hadn’t) and the engine was just revving but not accelerating…I tried all the gears with the same result…eventually my car slowed to a stop. A day later I had it towed to the mechanic…when he drove it it was fine, and did not exhibit the problem at all. He checked out the clutch and said it looked fine, and said my description of the problem made it sound as if the clutch had overheated…but he said that usually happens with city drivng, not on the highway.

So he is stumped…the car seems to be fine now, though I haven’t had it out on the highway yet. With a wife and 10-month old baby, I am nervous about this happening again. Does anyone have any ideas/insights? Any help is appreciated.

Thanks!
Mike

I’m not a tranny guy, but it sounds more to me like the shift linkage, perhaps something in the shift select lever shaft assembly, failed and dropped the tranny into neutral as well as negating shifting efforts.

The reason I’m thinking this is that the pressure plate assembly in its resting state clamps the clutchplate between itsself and the flywheel. The assembly itself is bolted to the flywheel, and the clutchplate is, by virtue of splines in its center hole slid onto splines in the tranny input shaft, attached to the tranny input shaft. I cannot envision any way the clutch assembly or any of its parts could suddenly and totally fail under load and then suddenly be okay again.

UNLESS you were shifting when it happened. If you were, then I’d suspect that the release bearing that pushes on the pressure plate forks mechanically stuck pressurized on the forks, holding the PP up off the clutchplate when you released the clutch. In that case, I’d say you need a new clutch assembly including the release bearing.

Were you shifting when it happened?

It could be the release bearing sticking, but I think this is the transmission shifting into neutral for some reason. Could be linkage, but if the mechanic already inspected the linkage, probably – sorry to say — a transmission problem.

Don’t see how it could have just slipped into neutral. OP said he tried it IN ALL gears.

A worn clutch is most likely to slip in high gear at high speed. That’s when it has the most load on it. Clutch serviceability can be tested in an open parking lot by firmly setting the parking brake, engaging top gear, and pretend you are starting off in first gear on a fairly steep hill…When you release the clutch, give it plenty of gas as you would for hard acceleration. The engine should stall as the clutch takes hold…If the engine does NOT stall, but allows the engine to operate with the car not moving, the clutch is worn out or very nearly worn out.

Should you perform this clutch test, do not allow the clutch to slip for any length of time or repeat the procedure more than once…

Good point, Caddyman. Normally I’d expect it to reengage when the gas pedal is lifted, but it’s certainly a possibility to keep in mind.