1999 silverado 1500 ext cab
4.3L 5 speed manual 2WD, 127k ... no prior symptoms regarding the clutch or transmission ... all parts are original including the clutch disc and fluid.

When pulling up to a stop sign tonight, a metal on metal rubbing noise started, seemingly from the clutch or transmission. I pulled over under a street light. The clutch fluid reservoir looked full.

The clutch pedal pushes in and out smoothly, but possibly requires less leg force to do so. There are no noises when in neutral and the clutch pedal is released. when the engine is turned off, i can shift into any gear. Sometimes i can shift into other gears when the truck is stationary and the engine is running. but when the truck is rolling, i can't get it out of gear (or into another gear).

If I start out in 2nd or 3rd, everything seems to operate fine and i was able to get it 4 miles to the parking garage at work ... but at one point it popped out of gear while driving, but I think this was because it was not fully into gear..

Any help in troubleshooting this would be appreciated.

mike

 

I'm wondering how to trouble shoot this without actually pulling the transmission ... not sure if it is a clutch component, the transmission, or ...

Thanks in advance.

 

Have the transmission fluid drained at a shop and catch that used fluid to inspect for metal shavings. Thats what I would do first because if the internals were grinding like you said you heard, there has to be some eveidence. Other than that, only thing I can think of the noise coming from is the throw out bearing seizing up.

 

Sounds like Pilot Bearing is bad. You need the trans input shaft to slow down when shifting gears (pushing clutch in) to shift. Also if no noise when in neutral and clutch pedal is not depressed the input shaft is spinning with the speed of the crankshaft, locked so input shaft is not spinning in the pilot bearing, no noise. Only way to see is trans removal.

 

RUFFNECK4LYFE -- Thanks for the idea to check the trans fluid for shavings. It is passed due for a change according to the repair manual (every 60k miles). Hopefully I can get to that tomorrow. Do you have any tips on getting the new fluid back into the case? or regarding types of fluid to use besides what is recommended in the Chevy owners manual?

 

acnas -- Your reasoning sounds solid regarding the pilot bearing. The online pictures show it to be a needle bearing. It seems to be the most simple repair as well, though everything I have been reading has recommended a complete rebuild regardless of the component. All components are original and so have 127k miles. I replaced the lower intake manifolds gaskets last year. Rebuilding the clutch sounds more simple, but a bigger pain due to weight and under truck work.

 

You will see 2 plugs on the side of the transmission. The lower will drain. The upper will allow for fill up. A reputable lube center can do this. Just let them know your situation in tryin to inspect the old fluid.

 

If you buy a clutch kit it should come with the pilot bearing. Wouldnt be a bad idea to change out the slave cylinder as well. Shouldn't be too bad of a job. 2wd is easier than a 4x4. Good luck.

 

I had a chance today to drive my truck about 5 miles.

When driving, I found I could shift in and out of gears 1,2,3,4 without using the clutch. When doing so, no noise is heard and everything runs smooth. I am wondering if this means that transmission is ok, and that the problem is in the clutch system.

The clutch resevoir is full (the diaphragm under the reservoir cap just touches the fluid), but there seems to be two liquids in the reservoir. I took a couple photos which I can post when I get home.

If I come to a full stop, then there may or may not be problems getting underway again. Sometimes it will shift into any gear using the clutch without having to stop the engine. Other times it will not shift into any gear at all, regardless of how far down I press the clutch pedal, and then I need to turn off the engine. With the engine off, I can shift in and out of any gear without using the clutch. This gives me two options -- restart the engine in neutral or in gear.

When I restart in neutral, sometimes I can shift into gear, other times not. When I am able, there is usually screeching / rubbing noises when I then shift from neutral to 2nd gear. The noise continues and changes as I let out the clutch pedal. But sometimes a restart in neutral will still not let me shift into gear. In this case, I turn off the engine yet again, shift into 2nd gear, and restart the engine.

Starting the engine in gear works only some of the times, because sometimes the truck just lurches because the transmission presumably is still engaged despite the clutch pedal being fully (or partially) depressed.

When I can get the engine restarted in gear, there is only a faint noise which would not be heard if the heater or radio was on. Other times, it causes the same screeching / rubbing noise that continues and changes pitch as I release the pedal.

In all of these scenarios, pumping the clutch pedal multiple times (as one might do with a slow brake fluid leak) has no effect.

I still need to check the transmission fluid, but on the upside, there are no signs of fluid leaks from the flywheel to the drive shaft, its all dry as a bone and there is a bit of rust on the flywheel.

 

What do you mean by 2 fluids in the reservoir?? Screeching could be a failed clutch disc that is wearing into the flywheel. Wouldn't recommend driving too much or flywheel damage could result. Some don't recommend resurfacing flywheels on hydraulic clutch systems but only replacing.