knocking from transmission housing

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  #1  
Old 02-20-04, 01:26 PM
onlyonehit
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knocking from transmission housing

i have a1994 chevy 1500 4.3,5 speed,theres a knock coming from the bellhousing area,ive changed out the throwout bearing and pressure plate etc,it kind of sounds like its coming from clutch fork in the housing area,the knocking noise quits when clutch pettle is engauged,reapears when depressed,shifts fine in all gears no shaking,or grinding noise just knocking,more gas louder the knock,can someone help me with this problem thank you!
 
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  #2  
Old 02-20-04, 02:38 PM
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Location: Long Island, NY
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Look at the crankshaft balancer while some one sits in the truck and works the pedal up and down with the engine running. If the front pulley moves you have worn thrust bearing on the crank.
 
  #3  
Old 02-20-04, 03:19 PM
onlyonehit
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knocking from transmission housing

THANK YOU FOR YOUR REPLY,I will do that,however wouldnt it knock in the engine area,instead of trans.housing,and knock all the time,the engine sounds great when clutch is pressed in,
 
  #4  
Old 02-20-04, 03:47 PM
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Your confusing me
the engine sounds great when clutch is pressed in
the knocking noise quits when clutch pettle is engauged,reapears when depressed,
The flywheel could rub on the back of the block.
 
  #5  
Old 02-20-04, 11:04 PM
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I agree. The thrust bearings could do this. Usually the crankshaft will knock at the very back bearing before anywhere else. It would be right there where the bellhousing bolts up. I guess the flywheel could be loose too, but I think that would be more noticeable than just a knock. Watch that harmonic balancer on the front of the engine as mentioned while someone presses/releases the clutch and truck is running in neutral with the park brake is on. If you can see it move, it's thrust bearings.
 
  #6  
Old 03-01-04, 04:27 PM
onlyonehit
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ive looked at the crank pully did not see movement like you mentioned,where else might i look for the problem,appreciate your inputs,thanks
 
  #7  
Old 03-01-04, 05:02 PM
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Did this noise start after you changed the parts? When exactly to you get the noise....there seems to be some confusion here.
 
  #8  
Old 03-02-04, 10:01 AM
onlyonehit
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The problem started as i was going down the highway approxitmatly 65 to 70 mph.i had some input from friend it was the throwout bearing so i changed that plus the pressure plate and clutch.the knocking stops when i press in on the clutch pedal! starts again when i let off the pedal!It does this in neutral as well as in all gears,The more gas you give it the louder and faster the knock.engine runs great,it also shifts in all gears great,no vibration as well,thanks for your trouble!!
 
  #9  
Old 03-02-04, 10:16 AM
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In neutral if you put your hand on the clutch fork can you feel the noise?
 
  #10  
Old 03-02-04, 10:32 AM
onlyonehit
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Ive thought of that but how do you check that when the clutch fork is in the bellhousing,there is a little hole about a half inch in diamemiture,on the back side of where i think the fork is,con i insret something in that hole to see if it is bouncing,or whatever,there is also a hole with a threaded plastic plug onthe side of the location where i think the fork is,can i put something in that hole to see if the fork is moving or whatever.
 
  #11  
Old 03-02-04, 01:39 PM
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Sounds like you have a internal set-up with a hydraulic slave cly.

It would hard to feel that type.
 
  #12  
Old 03-02-04, 02:52 PM
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To try to pin point the noise....does the noise stop when you just start to push the pedal or do you have to almost push it to the floor to get it to stop?
 
  #13  
Old 03-04-04, 09:17 AM
onlyonehit
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the knock seems to stop as your pushing down on the pedal
 
  #14  
Old 03-04-04, 09:26 AM
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Do I take that your just starting to push the pedal....like the first inch?
 
  #15  
Old 03-04-04, 09:59 AM
onlyonehit
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seems to be a little slop at first,but knock stops within 2 or 3 inchches from when the pedal seems to get stiffer.ps, truck wont start unless i press pedal all the way to the floor.
 
  #16  
Old 03-04-04, 09:16 PM
mike from nj
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larry, not to jump in on your conversation here, but based on 'description' alone, this sounds like an internal bearing noise inside the trans.

onehit:
when you slowly push the clutch pedal, first you're taking up the free play in the linkage, then when you hit slight resistance, that's when the clutch is actually disengaging the trans. if that's when you hear the noise 'slow down' and disappear, that's the internal gears slowing down and stopping.

what i do when i hear this noise is drain the trans fluid. when i take out the drain plug, if dust doesn't come out, usually 1/2 quart of very burnt fluid drips out, and with a ton of metal floating in it too, sometimes it looks like mercury! even though it's a manual trans, it still heats up the fluid and needs to be changed regularly.

bring it up to 2000 rpm, let the clutch in and out, you (i) can actually hear the gears and bearings make noise each time the pedal is let out, and slow down each time it's pushed in.

i'll butt out now
 
  #17  
Old 03-05-04, 12:36 AM
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Mike your not buttin in,

I guess you seen where I was goin with this. But I couldn't establish where the noise started or stopped in relation the clutch engagement.

Depending on that weather it trans gear, bearing or clutch or other problem.
 
  #18  
Old 03-05-04, 09:59 AM
onlyonehit
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Thanks for the input,so my fears came through,i need to replace the transmission,how much of a pain will it be to overhaul it?
 
  #19  
Old 03-06-04, 08:58 AM
mike from nj
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Originally posted by onlyonehit
how much of a pain will it be to overhaul it?

depends on if it's one bearing or all the bearings, or one gear or all the gears.

no matter what, it has to come completely apart, and if you forget or misplace one thing, it all has to come apart again. the labor alone to rebuild one is usually more than the cost of one from a salvage yard, just make sure you get one with a warranty. also---parts are not cheap inside a manual box.


i saw where you were going larry, i just saw the thread sitting there for 12 hours and tried to offer some input.
 
  #20  
Old 03-06-04, 09:39 AM
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Thanks Mike,

Its tuff diagnosing over the internet!
 
  #21  
Old 03-06-04, 12:03 PM
onlyonehit
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Thanks for the help guys ill see what i can do
 
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