So I just rebuilt an 89 pickup 3.0 6 cyl. It was a gift from my buddy- we rebuilt the engine from the crankshaft out. New everything, including clutch. This is my hunting rig, so I need to know it's not going to leave me stranded somewhere above 10,000 feet in the mountains. Here's the issue on my mind; the clutch has been replaced with a total kit including TO bearing, pilot bearing, pressure plate, etc... When I'm driving down the road and downshift, there is a brief "growl"/vibration that FEELS like it's coming from somewhere between the flywheel and the carrier bearing. The carrier bearing does have some play in it; I checked. However, there is no noise when just coming off the gas pedal, nor is there any kind of noise during acceleration. The only time it makes the noise is during downshift when the drivetrain has to come up to match the rpms of the motor. I've read other threads regarding similar concerns and they've left me rather confused. The TO bearing is brand new and the carrier bearing should be making noises at other times than JUST downshift/clutch release. Any ideas? Help me out, fellas!

 

Just because you replaced the clutch release bearing does not mean it is not failing already.

It should make the noise when ever the pedal is pushed in not just when down shifting.

Could be the fork is starting to crack

Just what brand clutch kit??

If you venture outside in the mountains one should be ready to spend several days in the mountains every time.waiting to be rescued.

Anything mechanical can and will break.

 

Not sure what brand the clutch is. I bought the preferred total clutch kit from NAPA. And the noise does not happen when the clutch is pushed down... it's only when I start to let it up, and only on a downshift that it happens. As for the mountains- I grew up at 9,000 feet. Me and the mountains have a loooooong love affair. I'm always ready for whatever they have to throw at me. I just don't want to call for a bail-out if I can avoid it. I always take care of any potential problem if I'm aware of it in advance!

 

Ok that sounds what your describing

Just normal stress from having the engine rpm different then the rest of the drive train.

The more difference in rpm the louder it will be.

When down shifting increase rpm before you pull it into the next lower gear..

Once you get used to the drivetrain you only need the clutch for pulling out.

Though any more people frown on doing that.

 

I do it but yea rev matching speed should quiet that right down.

 

what speed does it do the vibrating and the slip yoke on tjhe rear dline put the truck in neutral with the weels cholked check for play in thwe slip yoke. when you let off the gas the yoke will arch in a diffrent spot every time so the balance will not be consistant if the yoke can be twisted or pushed up n down with play that could be mostly or part of the problem its realy hard to tell unless a qualified tech takes a ride though i hope this helps do you get vibes at 55-65 mph

 

I think I fixed the problem... by fixing a totally "different" problem. My engine wasn't running with the power that a newly rebuilt engine should have; not by a long shot! Well, I figured out that my distributor shaft was installed one gear-tooth off. Upon re-installing the shaft, backed off that one tooth, the engine perked right up AND the growl was gone. I'm guessing that the sound was one of two things- either back pressure in the intake (due to valves being open when they weren't supposed to be) or premature release of exhaust gasses, again, due to valves being open when they weren't supposed to be. Either way, the only thing I changed was the timing- but it was WAY off, and now that it's right, the growl is totally gone. I have a truck that runs like it's supposed to now! Thank you, guys, for offering your thoughts.

 

I still do have one other problem though, one which you fellas might be very quick to know the answer to- my clutch! It's brand new, and it works, but damn! I have to mash the pedal ALL THE WAY to the floor to get it in gear. Sometimes it's very hard to get it into reverse... or first... or down into 2nd to make tight turns. The adjustment on the pedal has already been taken out some. I think it can go more... but I'm concerned that I'm looking at a larger problem- maybe my clutch master cylinder. How do I know if the mas cyl is going out rather than just a pedal out of adjustment? I'd hate to take my pedal WAY out just to find out that there's an even bigger problem.... Thoughts?

 

Look for clutch bracket fatigue. These brackets become week over time and slowly crack. So by depressing your pedal to the floor the bracket is flexing some as well and not fully engaging the clutch. If it is a small crack you might be able to weld it up. If its a big crack you probably have to fab a brace and bolt/weld it in there.

Also look under the hood at the clutch master cylinder. Is there any random fluid there? Then go down under the truck and look at the slave cylinder for the same thing. Sometime when we do a motor and clutch, the slave will get tweaked and the fitting becomes damaged. If this is your problem you might be able to fix the tweak or you might need a new slave. After going through this problem I have decided to spend the $100 every time I do a clutch and replace the slave and master at the same time. After all its only every 200k or so miles. Seems a pretty good return on investment. Good luck