Q I own a 2002 Chevy Cavalier with 74,000 miles on it. It has the five-speed manual transmission and hydraulic clutch. A year ago, I had a problem where it wouldn't shift right -- it didn't want to go into gear. The local Chevy dealer replaced a hydraulic hose that had deteriorated from a battery-acid leak.
Somewhat intermittently since then, I've been unable to shift into any gear unless the engine is turned off and the car is not moving. So it must be started in gear with the clutch pushed in. Then I let the clutch out, accelerate and shift into the next gear. If you sit with the car in first gear and the clutch pushed in, it will creep forward. If you try to put the car into first gear at a standstill with the clutch pushed in, it will try to creep forward. Other times, it will shift like new with no problems.
The dealer said the clutch, pressure plate and bearings are bad, and it will cost me $2,200 to fix it. I told them to stop, because I've never had a clutch go bad and then get better. A friend and I tried to bleed the clutch system, but with no improvement. What is wrong, and will I damage anything if I continue to drive it in this condition?
A To simplify the description of the problem, the clutch in your vehicle is intermittently failing to fully release -- or disengage -- the engine from the transmission. I agree with you that it is less likely to be a problem with the mechanical components of the clutch -- the pressure plate, clutch disc and release bearing. The hydraulic clutch release mechanism is a far more likely suspect. Either way, continuing to drive when this occurs definitely will shorten the life of the transmission synchronizers.
But first, let me describe one possible mechanical explanation for the intermittent clutch release -- the clutch disc binding on the input shaft splines. As the release bearing pushes inward on the pressure plate, the clamping force holding the clutch disc up against the flywheel is released, allowing the engine and flywheel to spin independently of the clutch disc, which is splined to the input shaft of the transmission. The disc must be able to slide just a bit on the splines. If it sticks or binds on the splines, it may not fully release from the flywheel and continue to feed engine torque through the input shaft into the transmission, which would create precisely the symptoms you've described. A burr or unusual wear on the spines might cause this binding.
Damage to the clutch disc itself or bent or broken diaphragm fingers on the pressure plate also can cause the clutch drag and failure to completely release that you've described, but those problems more likely would be consistent each time you pushed in the clutch pedal.
A more-common cause of intermittent clutch action is air invading the hydraulic clutch release mechanism through a worn seal in the clutch master or slave cylinder. GM suggests a special clutch bleeding process that involves filling the clutch master cylinder reservoir with brake fluid, then mounting a vacuum pump on the reservoir neck and repeatedly applying 20 inches of vacuum to the system until no more air bubbles appear.
If the clutch pedal feels a bit soft and spongy during the episodes where the clutch does not fully release, pump the clutch pedal to the floor a half-dozen times, then try shifting into gear. If the pumping action improves the clutch function, the problem is more likely hydraulic. A professional bleeding may help, but if the symptoms return, replacement of the clutch master and slave cylinders may be necessary. Unfortunately, in order to replace the clutch slave cylinder, the transmission must be removed from the vehicle, which is basically the same labor-intensive task required to replace the clutch mechanical components. At that point, you'd be wise to replace the pressure plate, disc and release bearing at the same time.
Q The air conditioning in my 2001 Saturn L200 went out. I brought it in and paid $140 for the shop to tell me it could not find a leak and it was completely out of Freon. So they refilled it and recharged it. Well, two days later it does not work again. Any suggestions?
A First off, Freon is history as a refrigerant in modern automobiles. Now, it's R-134a, which is more environmentally friendly. But that's OK -- it's like asking for a Kleenex rather than a tissue.
Obviously, the shop missed the leak. I'd suggest taking the vehicle to an automotive air conditioning specialist such as Dealer Automotive Services in Hopkins and Roseville who build automotive air-conditioning systems and service systems for dealers. They typically charge the system with inexpensive and safe nitrogen, find the leak, fix it, evacuate the nitrogen and any moisture, then recharge it with R-134a.
