mystery rattle- 1979 sII

M

mrscullini

Member
1979 sII, 345, t-19, 125k. basically all stock, no upgrades to the drive train.

i've got this intermittent mystery rattle, definitely a metal on metal. don't really hear it at idle. hear it under acceleration and while cruising. will have it under load and while coasting. definitely intermittent as it will go away while under load and cruising and then return. it seems to be coming from aft of the motor. at first, i thought it was the parking brake splitter bouncing off the cat. then i thought it was the cat internals bouncing around inside the cat. it has/had the original cat.

replaced the cat yesterday, still have the sound. pulled the inspection cover from the bell housing. now seems to be coming from the clutch. can't see anything obvious and nothing fell out of the bell housing. wondering if i may have lost a spring on the friction or pressure plate and it is rattling around. i also get pretty good chatter while taking off from a start, this makes me think i lost a spring(s).

i know it is difficult/impossible to diagnose mystery noises by forum. any thoughts?
 
mrscullini said:
1979 sII, 345, t-19, 125k. basically all stock, no upgrades to the drive train.

i've got this intermittent mystery rattle, definitely a metal on metal. don't really hear it at idle. hear it under acceleration and while cruising. will have it under load and while coasting. definitely intermittent as it will go away while under load and cruising and then return. it seems to be coming from aft of the motor. at first, i thought it was the parking brake splitter bouncing off the cat. then i thought it was the cat internals bouncing around inside the cat. it has/had the original cat.

replaced the cat yesterday, still have the sound. pulled the inspection cover from the bell housing. now seems to be coming from the clutch. can't see anything obvious and nothing fell out of the bell housing. wondering if i may have lost a spring on the friction or pressure plate and it is rattling around. i also get pretty good chatter while taking off from a start, this makes me think i lost a spring(s).

i know it is difficult/impossible to diagnose mystery noises by forum. any thoughts?
Click to expand...

Make sure your clutch is adjusted properly and then come back. It's in the service manual.
 
Winchested said:
Make sure your clutch is adjusted properly and then come back. It's in the service manual.
Click to expand...

thanks. gotta track down a service manual, i think my buddy has a copy.

in the meantime, i did search the web and found some specs. i seem to be out of adjustmet to a certain degree.

my pedal rest position is 9" off the floor board, per the search, this is the correct position.

my pedal free play is about 2 1/2", this seems too much. think it should be about an 1".

when the clutch is engaged, the throwout bearing is not in contact with the fingers on the pressure plate. i estimate there is about 1/4" of travel when the pedal is depressed before the bearing contacts the fingers.

the clutch definitely disengages. you can see the plates separate from the flywheel. i can shift and idle in gear so that says it.

the noise seems to be coming from the clutch, the head scratcher is that it doesn't seem to change much when the pedal is depressed and the clutch disengages.

i'll check the manual and also try to get a vid/audio.
 
Winchested said:
Make sure your clutch is adjusted properly and then come back. It's in the service manual.
Click to expand...

int77345 said:
check your drive shaft U joints also. iv had odd noises coming from them....
Click to expand...

thanks. u-joint seems to be ok. also, i get the rattle when the not in motion. it really seems to be coming from the clutch.

i tracked down a factory service manual and my clutch is way out. i have about 2 1/2" of free play. the clearance between the throwout bearing and fingers on the pressure plate is at least 1/4", maybe more. this is just an eyeball estimate as i watch the action as the pedal is depressed.

i now have the procedure for adjusting the clutch. will get under there this week and make the adjustment. i'll report back.
 
Winchested said:
Make sure your clutch is adjusted properly and then come back. It's in the service manual.
Click to expand...

got the clutch adjusted per the manual, pretty simple process. still have the rattle.

after some falling down some rabbit holes on the web, discovered that diesels had an issue with clutch rattle. did the gassers ever have this issue?

again, it doesn't really go away when the clutch is depressed. i think i've ruled out the TO bearing. thinking it may be a broken anti-chatter spring on the friction plate or a finger on the pressure plate.
 
tylus said:
Curious if you ever found out where is the rattling coming from.
Click to expand...

haven't found the source, however, i'm 99% sure it is the clutch. it still drives with no issues other than the noise and chatter when taking off from a stop. don't have the energy right now to pull the tranny.
 
mrscullini said:
haven't found the source, however, i'm 99% sure it is the clutch. it still drives with no issues other than the noise and chatter when taking off from a stop. don't have the energy right now to pull the tranny.
Click to expand...

Hope that doesn't drive any issue. My uncle is looking at a Florian SII as next project right after we finished installing the brake kit and chrome truck wheels on the current truck project. The current owner of the Florian is describing almost the same rattling noise he is suspecting from the clutch.
 
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