Intermittent noise on deceleration?

[jboarder16]

Hey my 88 k5 blazer is making an odd noise when im in 3rd of 4th when I'm going around 50 and up only when I let off the gas. It's not a constant noise it intermittent and won't do it every single time I take my foot Off, and I can feel the vibration slightly in the floor board? I checked my universal joints and greased them up they appeared to be fine, oh and it seems to stop when I put in my clutch? Any help would be appreciated, thanks

 

[crazy4offroad]

Could be the pilot bushing worn, throw-out bearing on it's way to failure, or loose bellhousing bolts causing misalignment of the input shaft.

 

[rainyraven]

yeah I agree with crazy4offroad sounds like the throw out bearing is going bye bye.. cheap part to fix but takes a while to get to it.. while your there you should put a new clutch in too.
I mean all that work you might as well make it worth your while.

 

[jboarder16]

Doesn't the pilot bearing spin only when u depress the clutch?? And the clutch and pilot bearing was replaced about 70,000 ago

 

[crazy4offroad]

If by pilot bearing you mean throw-out bearing, depends on how you have your clutch adjusted. When fully released it should be off the fingers of the pressure plate but if it is adjusted tighter it may be riding on it. I would check the bellhousing bolts for slack. The pilot bushing goes in the back end of the crankshaft, and the tip of the trans input shaft rides in it.

 

[Irishman999]

That clutch is hydraulic.

 

[jboarder16]

Yes that what I mean got my words mixed up, could it be the bell housing may e is loose? Is that a possibility??

 

[jboarder16]

So I just doubled checked my universal joints the one closest to the diff has a hair play on one side more than the other but fairly minimal, but I was looking at everything and the out put shaft on the transfer case seemed to have a little bit of play, not much but a little bit, about a month and a half ago I put on Orr shackle flip brackets on the back, I got a vibration right away so I shimmed the transfer case down 3/4 of an inch and put a 4' shim in the back and it completely took the vibration away. But the output shaft is sticking out about 1/2 more than stock so it appears, could it be the bearing on the back that is making noise? If so would be a big job replacing it?

 

[jboarder16]

There thing I could do is put those zero rate springs in the rear because they apparently can help u either move you axle forward or backwards if you need it, then I could get back a bit of the length in that output shaft? Or can I get it lengthed for cheap??

 

[jboarder16]

I think tomorrow I'll try dropping the transfer case a little bit

 

[Mike D]

Check the right motor mount, transmission mount ( also passenger side crossmember bolts ). Normally the engine torque pulls on the drivers ( left ) side in acceleration, conversly
the right side tries to rise ( pull ) on deceleration. Worn mounts or loose bolts will cause the engine to pulsate up and down, this is your vibration.

 

[jboarder16]

So I lowered the trams another 1/2 and the output shaft defiantly went in further and the noise is gone, weather it's gone for good not sure but seems good and feels good on the highway.

 

[jboarder16]

Oh I just saw your post, very interesting I think even the the vibration is gone for now the grand mount did seem to have a fair bit of movement... I should really replace them maybe moving the transfer case down is firming the mounts up by putting pressure on them??