Rattle on Decelleration

97SL

I've noticed when I'm in 3rd, at about 3500RPM and take my foot off
the throttle (i.e. engine braking) there's a loud, almost "rattling
chain" type sound from the engine. Is it the timing chain bouncing
around? Something wrong? As far as I can remember it's always made
this noise, however It's recently started to bother me, since I've
never heard it in any other car! (I have not gone to the saturn
dealer to 'compare' with another SL)

Does anyone have any ideas? Is this normal?

Thanks a lot!

 

....I'm thinking it's the throw-out bearing on the clutch - anyone else think
the same?

I've got a 97SL2 and I've been noticing a mechanical noise too when I let
off the throttle, especially on a downgrade.

 

On older engines this could be caused by knock as the vacuum advance
advanced the spark a whole lot. I wouldn't think the same thing
could happen with computer controlled ignition, but it might be
worth checking the mechanical timing of the distributor.

 

In my 2002 SL that kind of sound happens when I release the gas pedal
in any gear, often when I slow down to idle at stop. Saturn dealership
confirmed that, but could not find the source of the sound...

 

M/T - Gear Rattle

BULLETIN NO.: 95-T-37A

ISSUE DATE: March, 1999

GROUP/SEQ. NO.: Transaxle - 04

CORPORATION NO.: 99-07-31-001

SUBJECT:
Improved Manual :trans-axle Clutch Components and Updated Flywheel
Inspection Procedures

Due to revisions in the service procedures, this bulletin supercedes
bulletin 95-T-37, which should be discarded.

MODELS AFFECTED:

1991 - 1999 Saturn vehicles equipped with MP2 or MP3 manual transaxles

PURPOSE:

New manual transaxle clutch components have been developed to address gear
rattle concerns on 1996-1997 and 1998 vehicles built before and including
VIN WZ305219 equipped with MP2 or MP3 manual transaxles. The new components
include a long travel damper clutch disc (P/N 21120564) chamfered flywheel
(P/N 21120535) and new clutch cover (P/N 21120582). For the purpose of this
bulletin, they will be referred to as the 2nd design components. The 1st
design components consist of the past model clutch disc (P/N 21120453)
flywheel (P/N 21120542) and clutch cover (P/N 21120455). The 2nd design
components service Saturn vehicles back to the 1991 model year.

The 1st design and design components are interchangeable with one exception.
The 2nd design clutch disc is not compatible with the 1st design flywheel or
cover. Therefore, when servicing with the 2nd design clutch disc on 1991 -
1997 or 1998 vehicles with VIN WZ305219 and prior:

IMPORTANT: Mixing Of 1st and 2nd design clutch assembly components during
repairs will result in the reduction of the clutch disc life.

^ The 1st design flywheel must be chamfered or replaced with the 2nd
design flywheel.*(Refer to "Flywheel Chamfering" procedure listed in this
bulletin.) Failure to machine a chamfer on the flywheel could create a noise
concern in the manual transaxle as the clutch disc wears under normal
operating conditions.

*1998 VIN VZ278819 and greater already contain the 2nd design
chamfered flywheel.

^ The 1st design cover must be replaced with the and design cover.


The 1st design flywheel (P/N 21120542) maybe machined to create a chamfer so
that it is compatible with the 2nd design clutch disc (P/N 21120564). This
prevents a flywheel replacement every time the 1st design clutch disc is
replaced with a 2nd design disc. Listed below is the procedure for servicing
manual transaxle clutch components. In order to avoid service duplications,
check service history of vehicle prior to performing any of the service
procedures.

Also, when replacing the clutch disc and pressure plate due to normal
component wear, it may be necessary to replace the flywheel assembly to
ensure an effective friction surface. This bulletin provides guidelines to
help determine whether a flywheel should be replaced.

PARTS REQUIREMENTS:

21120535 Asm-Flywheel

21120564 Plate Asm-Clutch Driven

21120582 Cover Asm-Clutch Housing
ADDITIONAL ITEMS:

A protractor will be needed to create a template

 

S-Series had electronic ignition, there is no distributor.

Lane [ l a n e @ p a i r . c o m ]

 

Well, I'm definitly not thinking mechanical timing(since there is no
distributor....) or throwout bearing(since TO bearing problems generally arise
when you push in the clutch - nothing to do with gears themselves).

Excessive rattles could be caused by a worn out upper motor mount though. If it
has gotten worse then it originally was, maybe its due to that. Your best bet
is to either track down a mechanically inclined friend or if you want to spend
the $, go to the dealer and take a tech for a ride.

 

(BANDIT2941) typed until their fingers bled, and
came up with:

Actually, my TO bearing acted just as he described - would rattle when I
let off the gas and before I hit the clutch. The bearing has no pressure
on it until you hit the clutch, so it can get a bit loose in its arm.

 

Interesting........I've always heard them rattle while in neutral, as opposed
to when driving. To the TO bearing I don't think it matters whether you're
actually moving for they symptoms to occur.

 

Wow! Thanks for all the quick replies!

I have noticed the gear rattle for a while... but other than minor
rattle it doesn't bother me.

The rattle that I've been concerned about however is a high-pitched
rattle (decelerating at a high RPM in any gear, just used 3rd as an
example), and it's definately coming from the engine compartment..

I think I may end up taking it down the dealer just to have a
listen... I suppose the best way I can describe the noise is like a
rattling chain.

Thanks again for the replies.

 

You can get a high-pitched whine (gear noise) out of a manual
transmission when downshifting, due simply to running on the "back
sides" of the gear teeth. This is nothing to worry about.

 

Cool, Kirk!