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Re: 2.3 Balance Shaft Chain
Posted by Bernard Wassertzug (more from Bernard Wassertzug) on Tue, 28 Nov 2000 13:23:50
In Reply to: , Kok Chen, Sat, 17 Dec 1988 12:00:00 

Three years ago I faced a similar situation and decided to do the job 
myself, after which I wrote the following notes. Hopefully these will 
answer most of your questions, and I'll be glad to answer any additional 
ones:

In November 97 I bought a 1992 9000 non-Turbo with 100K miles.  An 
independent shop inspected it, and found a noisy timing chain, and perhaps 
balance chain too'.  Their proposed solution was to  roll-in a new timing 
chain (as per PSI 07/93-0357 'Changing the Timing Chain: Engine in Vehicle, 
16-valve') for $400, and 'if that didn't do it', they would then replace 
'everything' for an additional $1200.

Having once lost a 16V engine on a 86 900S with 100K miles due to a broken 
cam chain, I was particularly jittery about this.  And since this shop had 
serviced the car since new and had seriously mismanaged it, I decided to 
tackle the job myself and change everything that needed changing.  I have 
done much work on the classic 900s, but this was my first 9000 and it 
seemed like a jigsaw puzzle.  At the time, my only reference was the Haynes 
manual; to its credit, it DOES mention the left thread on the tensioner 
pulley bolt  [but I endorse Stephen Goldbergers recommendation to get hold 
of a 2.3 Basic Engine manual covering your model year.  It is much more 
detailed and also shows the various special tools, which helped me build a 
home-made flywheel locking tool -- the only way to remove and tighten the 
crankshaft pulley].

  I chose to remove the timing cover (engine in car) while leaving the head 
in place, which proved to be a bad decision (see below). I found the cam 
and balance shaft chain tensioners extended 11.5mm and 11mm, 
respectively.  According to the PSI: 'Under no circumstances should the 
chain tensioner extend by more than 11 mm.  If it exceeds this measurement, 
the chain should be replaced' (this seems to be the only official' Saab 
word on the subject; none of the Saab Service Books, to the best of my 
knowledge, provides any specs at all). Also, according to the PSI, given 
the slight timing chain guide and sprocket wear I found, there was no need 
to replace them and the 'roll-in' chain procedure was therefore 
appropriate.  I decided to replace both chains and all the guides but found 
that the pivoting timing chain guide cannot be removed with the head 
installed, so I left it in place (its wear was minor) and replaced all the 
others. I also replaced the balance shaft crank sprocket, that showed 
SERIOUS tooth wear!  Both tensioners were in good shape, and I reused them.

Until this point I assumed that the increased tensioner extension was due 
to chain stretch, even when the camshaft marks still lined up well within 
specs at TDC.  But when the new chains arrived I was very surprised to find 
that their length was EXACTLY equal to the old ones, invalidating the 
stretch assumption.  I also compared the lateral deflection of the new and 
old chains -- supposedly a measure of chain pin wear.  I found an increased 
deflection for the used chains: the cam chain increased from 160mm to 
240mm; the balance shaft chain -- from 125mm to 150mm.  This is not very 
significant, IMHO but again -- there are no official Saab specs on the subject.

After assembling the new components, the cam and balance shaft tensioner 
extensions were 7mm and 9mm, respectively.  I attribute the reduction to 
the new guides; had I changed the pivoting cam chain guide as well, the 7mm 
would probably have decreased to 4 or 5mm. Since the cam chain tensioner 
has an extension range of 2mm to 18mm, I seriously question the chain 
replacement at 11mm mandated by the PSI; the pivoting guide has room to 
move up to the 18mm max tensioner extension without any 
interference.  Furthermore, had I followed the PSI advice and replaced only 
the cam chain -- and not the guides -- I would have gone back to the 
original 11.5mm extension, since the new chain is exactly as long as the 
old one!  And I have would have left the worn balance chain sprocket in 
place, a sure prescription for disaster In my opinion, this PSI should be 
disregarded  especially when dealing with 2.3L balance shaft engines [and 
it probably has been, since I havent heard much talk about it recently].

Inserting the timing cover between the head gasket and the oil pan -- 
working through the hole in the inner fender while squatting under it -- is 
a mission impossible: I damaged the head gasket, as predicted by the Haynes 
book. I tried to repair it but finally replaced it, which turned out to be 
good news since I found corrosive coolant damage in several spots of the 
old gasket.  In summary, had I removed the head initially I would have 
saved myself some extra work and would have been able to replace the 
pivoting guide too.  Replacing the head gasket at 100K miles is probably a 
good preventive measure in any case.

Was the 'noisy timing chain' fixed?  The answer is NO!  The noise was still 
there when I restarted the engine!  But I discovered (by chance) another 
PSI (10/91-0145 'Fuel Pulsation noise') that states:
'Some 1990-on 9000 vehicles with the 2.3 liter engine may develop a 
pulsation noise that can be heard inside the car.  Customer complaints 
often refer to a tapping or knocking sound that is heard when the car is 
idling at a stop.  The most likely cause of this noise is a faulty fuel 
line damper, located between the fuel supply line and the distribution rail 
on the engine... A new damper, P/N 41 64 232, containing a spring-loaded 
diaphragm has been developed for use as a service measure.  A modified 
version of this damper will also be introduced as a running change during 
mid-1992 production.'
My car was built in late '92, but still had the faulty damper.  Having gone 
this far, I decided to try this out and it worked!  It only took about 20 
minutes to install, and the noise was finally gone!  I was very pleased, of 
course, but this reopened the Pandora box: why isn't this important 
information included in the Saab Service books?  This would be greatly 
appreciated by users that choose to learn about their cars and maintain 
them themselves, and that were supported in their efforts by Saab for many 
years.

PS: The work took me about 2 weeks, working in an unheated garage in very 
cold weather.  When I finished, we tried out the car around the block a few 
times and it has run without problems for 50K miles except for regular 
maintenance and a few replaced parts (the ignition cassette, the air mass 
meter and the front exhaust pipe).
Best regards, Bernie

Bernard Wassertzug
11825 Enid Drive
Rockville, MD 20854-3455
Tel. (301) 299-8561

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