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Discussion Starter · #1 ·
What happens if ballance shaft sprockets are not set up properly, i.e. timing marks not quite right when chain fitted ? I have uneven idle problem,have fitted new sprockets and chains and do not want to strip down again if not the problem, any advice will be appreciated by a complete novice.
 
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When my balance shaft chain jumped a tooth or two, it felt to me as though I had an engine mounting gone. Loads of vibration, but the actual idle speed was steady.

Pete
Gloucester
UK
9000S 2.3 Turbo
 

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I have a J-Reg 9000 CSE 2.3 Turbo Auto which I bought in Mid Nov 00. The idle speed is fine but on start up the vibration is very bad, causing the dashboard to shake. Increase the revs slightly and everything is OK. When the engine is warm the vibration at idle is less but still v. annoying. Putting the autobox into neutral when stationary improves it a bit.

One of the lower engine mounts has been changed. I am loathe to change all the rest on the off chance that they are bad (they look OK). I have a 900S 16V and had a 9000 2.0T - both engines idled without vibration whereas this one would empty a mug of coffee placed on the head in about 20 seconds.

Looking at the service history the timing chain was changed in Feb 99 by a non SAAB garage (more a tyre and exhaust outlet!). £49 for the chain, £30 gaskets and £100 labour. From reading the Haynes manual the balance chain has to be removed first before the timing chain...maybe the balance chain was put on wrongly!

Do the counter balance shafts just have an effect at low engine revs?

Does anyone else have/had a similar problem?
 
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Sounds to me exactly like mine did when it jumped a tooth or two. I can't believe that anyone could do that job for that cost! I can't remember what mine was like at higher revs (I was too scared to rev it much!). If your montings are gone, you'll be able to grab hold of the engine and move it around. Mine was rock steady, but sounded & felt like a bag of old nails. Much the same as when an exhaust is knocking on the body/chassis. If the garage didn't change any sprockets etc I would suspect that a cheap job was done to allow the car to be sold on. Sorry! What mileage has it done? Those balance shaft sprockets don't stand the miles very well.
 

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Thanks for the info Pete. The mileage is 137,000m. It loooks like I am going to have to get my mechanic to strip down and check the state of the timing chain (sprockets, guides and tensioners) and do the same for the balance chain (sprockets, guides and tensioners including tooth alignment. I have just checked the engine mounts; the Engine doesn't move apart from a little down movement if I lean right on top of it. I'll break the news to him tomorrow when he replaces the auxiliary drive belt, idler pulleys and auto tensioner.......after the orginal one came off after the rear idler pully disintegrated.
 

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An uneven idle could be due to a few things, but most likely the Idle Control Valve (IDC). It may just need cleaning (use a clean lint free cotton rag - but avoid solvents due to the electrics), due to having acumulated oil from the breather. OEM (Bosch) IDC are approx GBP80 from Neo bros, or 2 Stoke 2 Turbo. Dealers charge GBP160!!

As there are two ballance shafts, they both need setting correctly. I once had a balance shaft 'belt' changed on a Mitsubishi Gallant (sorry for swearing), and the guy only set one shaft correctly, and it sounded like I had a blown exhaust pipe due to the vibrations.

B-regards,
Paul D.
 

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I got my chains done. Timing and balance chains worn. The mechanic noticed a strange resonance being set up in the exhaust. I am not sure if the balance shafts were misaligned, the mechanic just went ahead and changed all the bits. The top engine mounts were worn and had being installed the wrong way round! These were replaced into the original bushes and inserted correctly. The whole car is much much smoother and my conficence is restored.

There is still a little booming from the exhaust, present on both lpg and petrol. I might have a clean up of the Idle Control Valve but I don't think that this affects the lpg operation.

Gavin
'92 9000 CSE 2.3 Turbo Auto lpg
 
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