Clutch, Master/Slave or something else?

[MrBiggz]

Hey all! I need some help diagnosing my girlfriends 2008 Chevy Cobalt LS XFE. A mechanic friend of ours suggested that it may be a master or slave cylinder (I believe hoping to save us some money on parts. He didn't actually look at the car because he's been super busy) but it seems like a clutch issue to me. Any advice or insight into diagnosis is welcome. I will try to give all the info I can and will be actively checking this post for replies or if you need more info from me, let me know.

Over a period of about 2-3 days the car lost power to the wheels. For example, I live on a large hill with a fairly steep grade and on Day 1, I could tell that the engine was revving higher than normal but was still climbing. Day 2, I had to shift to second instead of third gear to get up the hill and it was revving high. Day 3, Literally couldn't get enough power to the wheels to get up the hill even though the engine revved up.

The car has sat in front of the house for about 2 weeks but today i moved it and it had enough power to wheels to slowly get around to the alley, into the garage and on stands.
It shifts into gears easily while on or off.
The brake fluid level in the reservoir is good.
No leaks beneath Master cylinder or Slave cylinder.

(Went out to get mileage off of car and got electrocuted by a lamp in the dark, said F it , somewhere aroung 60k miles.)

Looking to buy parts and fix it within the next couple days.

 

[YelloEye]

The clutch slave and master cylinders only affect your ability to get into and out of a gear, if you can shift into gears that's not the problem.

The clutch is pinched by the pressure plate up against the flywheel to drive the transmission input shaft, what you're describing sounds somewhat like clutch slip. What happens when the clutch is slipping is that the engine seems to have a "breaking point", it'll provide power fine up until a certain TQ value and then the clutch starts slipping, applying more power only serves to make it slip more and damages the clutch friction surfaces more.

There are a couple reasons that your clutch might be failing, the most common with this car is that people are riding the clutch too much or are actuating the clutch too slowly. Both of these will cause a low friction condition where the clutch is heated up and begins to glaze it which makes it a terrible friction surface.

I had this begin to happen when I had my 06 LT a year after purchase, I sold it at 90k 2 years later and it was fine. How did I fix it?

The advice I followed to repair the damage was to never shift below 3k, and always engage and disengage the clutch as rapidly as comfortable (not sidestepping the clutch pedal). Not even a week later the clutch was good as new.

To prevent it from happening in the future keep your foot off the clutch when you're not using it, there's a dead pedal on the left for just that reason. Shift above 3k and don't burn the clutch by babying the pedal.

 

[MrBiggz]

The clutch slave and master cylinders only affect your ability to get into and out of a gear, if you can shift into gears that's not the problem.

Good to know. That eliminates 2 of the 3 things I was questioning.

The advice I followed to repair the damage was to never shift below 3k, and always engage and disengage the clutch as rapidly as comfortable (not sidestepping the clutch pedal). Not even a week later the clutch was good as new.

I'm pretty sure the clutch is beyond being fixed by proper driving habits. Is there any way I can confirm that the issue is with the clutch and not something else? So I can begin repairs. The car isn't drivable enough right now to even begin driving the way you describe. Although I'm sure you are correct about why it went out in the first place.

Have you ever changed a clutch in a Cobalt?
I bought a Chilton's manual yesterday for the car, but would be interested in any other helpful info or tips for the procedure.

 

[YelloEye]

There's only 2 reasons the car will rev higher while not accelerating, either you're burning rubber, or the clutch/pressure plate aren't working correctly.

 

[Justinw303]

Wow, I had no idea clutch damage could be "repaired" in any way, thanks for the insight Yello!

 

[YelloEye]

It's worth a shot, no guarantee it'll fix it.