Date: Sun, 05 Sep 2004 13:20:48 -0300
From: Dexter J <lamealameadingdongnospamlamelame.org>
Subject: Re: 9000 Auto Transmission Problem


Salutations: Sorry to top post - but the details of your problem are important and probably should be left with this lengthy reply. Basically - an automatic transmission is a complicated high pressure pump fed by the torque converter which powers a fluid/ hydraulic drive solution. Unlike a manual transmission - there is no direct metal to metal connection between the engine and the differential until the torque converter 'locks' and/or 'stalls' under very specific conditions and even then a true direct engine/differential connect is debatable. Normally - the valve bodies channel the pressurized oil at different rates appropriate to the speed of the differential and engine RPM. Primary pressure being developed in the torque converter is passed through a liquid circuit to a various sets of clutch packs (if you've ever owned a motorcycle - they look sort of like the clutch basket on a much smaller scale but longer length - like a long stack of poker chips). The pressure developed by the torque converter is appropriately metered through the circuit(s) to the clutch packs using spring valves, vacuum and in some cases electronics - against a known fluid viscosity and pressure in the circuit(s) (different transmission fluid types) so that the transmission can be pre-set to use different circuits as appropriate to the load feedback being felt through the differential and the pressure being applied by the advanced rotary pump that is the torque converter. When an automatic transmission starts to miss or jolt it may be a single fault in the circuit - or a combination of many smaller faults in the circuit(s) - or some greater fault outside the circuit. Given the really quite deep diagnoses time required to figure out which, or which combination, things are generating the fault and the fact that the problem may additionally complicated by the fact that deterioration in one part of the circuit may contaminate another part of the circuit so that it's flow characteristics change - most folks opt to simply replace the transmission and/or sometimes the entire power train with a known complete good unit when a deterioration type fault develops. This is premature in many cases given that an automatic transmission may not detererate further for some tens of thousands of miles/kilometers - or it may become evident later that it is some system feeding the logic of the transmission that is at fault (say a momentary cut off by the engine protection system). However - this is a gamble given that your transmission may also fail outright even after replacing a suspect part (like valve bodies) and leave you stranded with several hundred's of dollars in towing assuming it doesn't fail catastrophically and blow fluid all over a hot exhaust on a dry day and burn your car down and assuming an upstream problem like an engine protection system cut out doesn't itself come to damage the transmission. Were I in your position - I would have a really good shop put a pressure and temperature gauge on the transmission on a dyno and confirm it is running within specifications. If not - I would be looking at the torque converter, supporting drive systems and differential given you've already done several important internal tranny systems. Beware - I parked a perfectly good motor home for a couple of years when the local GMC dealer here in Halifax/Dartmouth (Nova Scotia) swore up and down that my TH425 transmission was busted - when in fact they had completely botched a simple filter change so that the filter o-ring was pitched and was simply drawing air at the pick-up tube in the tranny pan. With almost exactly the same symptoms you are describing incidentally.. Anyway - I would also have the tranny filter pulled and cut open by someone who knows their stuff to confirm if there are any larger bits of clutch, gasket, gasket sealer or metal moving through the system. This is not a final answer - if there is contamination - you need to know where it came from and why. There are almost always bits after service unless the technician is *really* meticulous - and even then when the new parts are 'breaking in' it may appear to be problem when it is in fact normal. In point of fact - if your filter is perfectly clean at this point you may want to know where the 'break in' crud is actually going. If everything is peachy down there according to someone you can *really* trust - I would be looking at the engine management system given another experience of mine with my 89' 9000 Turbo automatic which was (finally) traced back to an ignition fault that saw the engine management system very briefly cutting in and out when an spark plug grounded, which was read as a knock by the ECM system. This caused the 9000 to momentarily buck, eventually violently, under boost and was repeatedly diagnosed to be a transmission problem instead of the real culprit - a 5 cent o-ring on the distributor. Personally - I have moved back to 5 speeds on my SAAB(s) given the proprietary diagnostics requirements on an already complicated engine and drive management system. If I could fit one - I would actually prefer an old 4 speed off an early 99/900 (particularly on a modern turbo). This is not to say that the automatic is a bad tranny - frankly it was the best automatic transmission in terms of drive I've run - but because it was so hard to find anyone to actually correctly diagnose tranny problems these days, it started to make sense to move back to a 5 speed despite the learning curve required of the rest of the family to operate it. Hope it works out - lovely machine and not too expensive to convert to five speed - all things considered and all avenues exhausted. -- J Dexter - webmaster - http://www.dexterdyne.org/ all tunes - no cookies no subscription no weather no ads no news no phone in - RealAudio 8+ Required - all the Time Radio Free Dexterdyne Top Tune o'be-do-da-day En Vogue - Giving Him Everything He Can Feel http://www.dexterdyne.org/888/118.RAM On Fri, 03 Sep 2004 16:34:50 +0100, PJDK <pnospamm> wrote: > My '98 9000 Anniversary 2.3T Auto (100,000 miles) is misbehaving and my > dealer is having problems so any sage advice or observations will be > greatly appreciated... > > A month or two ago, as I was driving off the motorway and coming to a > stop, I felt a jolt just before the car actually stopped at the > junction. It was like something had gently rear ended me. No engine > racing as far as I can remember or anything else odd. > > I half dismissed it as a rough/late change-down though I've never > experienced anything like this before. I was near home so I just drove > back gently but noticed similar jolts again, always just before actually > stopping. None of them were as dramatic as the first though. The jolt is > literally just before the car stops. My previous 9000 didn't do it (at > 160,000 miles with no rebuilt transmission) and neither does the other > one that I drive from time to time. > > Just to be on the safe side I had the car taken to my local Saab dealer > where they diagnosed an internal fault in the transmission. The unit was > taken out and sent off to a specialist for a re-build. While it was > still open on the bench the mechanic called me to ask for more specific > information about the problem as he couldn't see anything wrong. The > transmission was overhauled, the seals etc. replaced, and put back in > the car. It made no positive difference at all. On the negative side > (apart from the 1400 GBP that it cost!) sometimes when accelerating from > very slow speed or stopped it doesn't seem to "engage" first properly > and races slightly before down shifting. > > So, the car went straight back and this time the "valve body" was > replaced. I went for a test drive with the "rebuilder" who said that the > jolt (which when we went out was not very obvious - it is erratic > anyway) was not curable and was just something that every auto > transmission does. He couldn't explain why the other 9000's I drive/have > driven don't exhibit this behaviour at all though. He was sure that the > more recent problem with first not engaging properly would be cured with > the new valve body - it wasn't. > > The dealer is looking into the problem and is talking about replacing > the transmission completely but in the meantime I'm wondering if anybody > here has any ideas about what could be causing this. > > Thanks in advance. > > Piers > > pierskenney (a t) tiscali (d o t) co (d o t) uk

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