changing Timing chain and balance chain

There are rumours that it can be done in the car - but you probably want to pull the engine and do the gaskets, seals, pumps and re-brush the alternator anyway at 140,000.

My take would be that it is going to run about the same shop hours to do the chains in the car as pulling and benching the engine - but you can address anything else you find along the way on the bench.

Dexter Thanks for info, looks a bit expensive then. Dave

I have done the chains in the car on a 9000 but (not a 900) and it was not very difficult. It requires moving the AC compressor, and removing the water pump, but it was far easier to do with the engine in the car than the effort to remove it.

On a 9000 you remove the inner fender liner and it gives you good access through the wheel well. I do not recall if that is how a NG900 is as well.

-Fred W

Hey Fred, good to read you again.

Sadly, the NG900 is a just tight enough fit that while you can remove all the peripherals and the chain case - you can't easily withdraw the balance shafts replace the cogs (which most likely are what wore out the chain prematurely - which then leads you to review the oil pick-up and gallery for sludging) without unbolting the engine from the mounts and the complete facing suspension and hub assembly from the upper shock mount and inner CV joint out. Basically you have to shift the motor around in the bay a couple of times to get at things - and that isn't for the faint of heart with old lines and delicate harnesses.

I figure it's six or one half dozen of the other hours wise - but only if all you have to fix in the chain case is the actual chains, which is rarely the case. Interestingly, none of the actual parts in the chain case or oil gallery are all that expensive - but the hours to do the complete job either way are at least 10.

So, my suggestion is based in the premise that it is just as easy to pull a whole front wheel drive power, tranny and all, out and bench it. Simply unbolt the mounts and systems and lift. There is probably equally qualified opinion that it is better not to disturb the harness, vacuum and hydraulic systems and try to fix it in the car. Which is OK too I guess, as long as everything else besides the actual chains are in good working order.

But - if I'm faced with at least 10 shop hours either way - I figure it's a good value to have a 140,000 mile engine clear of the car so that anything needing attention can be done easily and relatively cheaply all at once. It allows for the more value for hours at the end of the day I think.

I'm back to a 9000 now myself as you may remember - a '93 5 speed aero in fact - but I must say that the NG900 isn't nearly as bad as I had feared. We still have the NG900 we picked up last winter as I haven't be able to find a local buyer for it yet. Our '94 S model is *VERY* sporty unit all things considered - and really quite reliable with an LH Bosch ignition system too.

Assuming the body on this '95 is good shape - it is worth the effort to fix the systems properly as the owner will likely get another 140,000 out it before anything serious goes wrong in the engine bay. Check over the tranny before you proceed however, 1994 and onward are good years - but trouble there could tip the scales the other way *long term owner value wise* of course.

Could the noise come from valve adjusters ?

I think that's quite common cause for cold start noise in those engines.

If it would be from chain why quiet when warm ?

br Vesa

Many thanks Dexter for all the typing!! I have decided to have the work done as the body is realy good and front shocks and brake disks have been replaced in last year and rest of car is in good shape, so fingers crossed it should run on for a few years yet. My reasoning is I cant sell car for much with engine faulty, and to replace it with a similar age one I may end up with the same and / or other problems and I cant aford a nice shiny new one yet!

Vesku I dont think its valve adjuster, it is deffinitly a rattle and a sliding metal over metal sound - cant realy describe in words. I have had two opinions from 2 good garages both think its chains. Presumably when engine is warm the tolerances change as it expand so it quietens?

Dave

You appreciate that any advise presented in this form is only offered with all the usual disclaimers.. :/ ..

Anyway - brother Vesku may well be moving along a correct line. It may well be that you are not making enough oil pressure to fully apply the tensioner until the oil warms up enough to thin. The timing chain itself may also be stretched a little and the combination is presenting as loose.

If this is the case - the lash noise will sometimes last longer with fresh heavier grade oil.

It is therefore vitally important that you have the chain measured very carefully before you close up the case to confirm it is *well* outside of specification. 140,000 miles is a little early for a SAAB timing chain to go loose actually - and thus, you may well be suffering from bad oil pick-up as well. Some 2.3 engines have a problem with wax forming on the strainer or in the pump housing.

That said - it may well also only be the balance chain alone as that is a known culprit in a middle aged 2.3 engine. Several folks have had their

2.3's modified to remove the balancers and I may well give it a try when I have to do mine in the aero.

In short - you want to know as much about *why* the chain is making noise before you start replacing parts. Very best of luck with it brother Dave - I think you should put in some google time over the weekend regarding this so as to be able to discuss it with your shop carefully.

It is at this point that a greater SAAB/Owner relationship can become either a complete paradise as you both get another 140,000 miles smiling all the way to the bank - or - a joy of life sucking vampire from which there is no financial escape short of a loose road flare in the trunk and a no service cell phone zone.

Here at alt.autos.saab we always hope it's the former.

Cheers.

Many thanks for comments, also to Fred and Vesku Yes I do appreciate these comments are without warranty etc! But it is a good place to knock around ideas.

I did wonder if oil may be a problem at first but went away from that idea as it sounded more like chain, dont know is probably better answer!

The exploratory op is starting next week, so I'll have a surf round net and have a chat with my garage, who are usualy realy good.and do not mind talking though before hand etc. Like Vesku said why does it get quiet when warm, I just thought of expansion of engine/chain etc, is there any easier way to check the oil idea first.

And showing my lack of knowledge - does the oil pressure apply the tensioner - if I read your comment correctly or is it just spring loaded?

One last thought the car was running a bit rough for a few weeks so 2 weeks ago we suspected dirty injectors, so put some redex in last two tank fulls of petrol, presumably this would not cause this at it is just in fuel areas not the oil. Car runs great now except for noises.

Regards Dave

There isn't that much expansion in the engine and very little on the chain on heating unless it is getting way too warm.

So - while there is usually more noise on start up - it usually relates to the oil itself being at the top end of it's viscosity range until it warms up and starts to flow into the compressed surfaces more freely. If you had an oil gauge you would note that start up pressure was a little less than twice that of running pressure. This extra pressure is the engine working harder to oil the parts - not more flow of oil around the engine.

This is why folks are starting to go for really good Moly Synthetic oils which generally coat the parts a little better between starts and maintain a more even, though lower, pressure across the heat range. Unfortunately you have to really buy the good stuff and not some cut rate brand that claims to do the business.

The tensioner system is sprung in the 2.3 engine - but there are two systems in play - the balance shafts and the main timing chain. The balance shaft tensioner is internal to the timing case and subject to oil problems. The timing chain tensioner starts at that little bolt head you see on the rear of the head above the alternator. It is less sensitive to oiling problems - but overheating problems can be severe in the extreme.

Somewhere, and I can't seem to find it now, there is a really good photo-illustrated balance shaft removal and modification page that shows all the details of both these systems and workings. If you come across it in your travels I would dearly love the link for my bookmarks here.

You were correct to worry about the rough idle as a severely loose timing chain would indeed also present as rough idle. A slightly worn timing chain would naturally I think exacerbate slightly gummy injectors. A noisey enough chain will I understand trigger the engine knock sensor at higher revs in some cases.

I guess my point in all this is that you may have one of two wear issues or several wear issues in greater or lesser degrees. It is really worth knowing which before you put the engine back and why I recommended pulling the engine in the first place. Basically - most of the wear parts are pretty cheap - but the labour to get to them individually is pretty steep every time.

Now - one of the things I like about used higher end european cars is that they have usually been pretty much completely rebuildable from the main bearing caps out. For the most part - they started on an engineering premise that sees them being serviced rather than scrapped at higher mileage.

Often, in my mind at least, a lot of folks who pick up a used SAAB somewhere don't really get this, but then get really ticked off when repairs start to come on one after the other. However, if they were instead to approach repairs in terms of 'whole systems' - they would discover that it can be much cheaper to keep a SAAB on the road than most over time.

My .2 cents (.07p to the Pound).. There are those who would vehemently disagree with me.

On the subject of timing chains, I have finally obtained a new timing chain (with master link) and a new timing chain tensioner kit (the newer type) to keep in spares for when I need to replace the timing chain in the 8V B201 engine in my 1982/83 900S. The engine car has done almost 250 k km's so it's definitely in the ballpark range for timing chain problems to become evident, though at the moment (without getting the car over to a proper Saab service dealer) I don't think there are any high-demand problems with the timing chain, etc.

Has anyone done an engine-in-place replacement of the timing chain and/or chain tensioner in an 8V 900? Was there anything good or bad that you remember about doing it? I've seen a few references on the web about the process but have not spoken to anyone who's actually done it.

I agree with most people that lifting the engine out just to do a timing chain is probably a very expensive option unless it's also used to do other things which can't really be done when the engine is in the car. However, when facilities to life an engine are not available locally without taking the car to a Saab service agent (and paying for the labour more than anything else to get the job done), is there anything special to watch out for?

Regards,

Craig.

You know, I cannot remember ever having to do the timing chain and guides in my old 900 engine right out to about 900,000km.. But it may have been an earlier A model block, I had the pump pressed in the block. The chain got a little loose towards the end, and it was natively 'Jet Sounding' to begin with - but it was the reversing 5 ton in the parking lot that finally did her in.

Assuming you have you checked your pumps and alternator carefully - I would be just looking at the main tensioner spring before going to deep in myself. I did have to do that around 300,000km.

All that said - given you are 8v, a skilled hand should be able to thread the chain in most normal instances. There shouldn't be a secondary balance chain in this engine, so it is rational to try it before lifting the engine out. Butter fingers will get expensive quickly though.

A lot of people don't bother replacing the balance shaft chain system(where fitted) on 9000s at least. One of my 9000s snapped its chain(s) in 2001 and the garage rang me to ask if I wanted to bother with the balance shaft chain or should they just leave it off. I said leave it off and I can't say I really notce the difference except that the engine seems a lot more responsive than most 9000s I have driven.

Any one know more about this one?

Cheers

Paul BJ

As you may have noted - I've taken an unhealthy interest in machine chains over the years. I am thinking seriously about the same mod in the coming year or so. My only concern I guess would be how it will impact the lower engine mounts on an older HO engine.

While the compression is strong, it is light about 10pds at number three hole on a fresh gasket and that is probably the way it is going to stay until I blow the engine or turbo. Thus, while I would dearly like to lose the drivetrain weight, I am worried that the vibration will start consumming the oil mounts *even faster* than on my last one.

Did you go for the pucks or do you still have factory lower mounts and are you 5 speed? Whats you engine like outside of the balance shaft mod?

Mine is a bit of an old banger so I left the old engine mounts in there. They did go...two years later after a LOT of miles....but they might well have been on their way out anyway!

The engine is a standard 2.3 FPT from a 1991 5 speed 9000S.

You imply that some sort of engine mounts other than Saab are preferable...is that right?

Cheers

Paul BJ

I'm trying to get a handle on the vibration factor once the balance chains are out of the loop.

Factory or after market hydraulic mounts will naturally absorb any extra vibration, but I went through my last lower set pretty fast. It may have been a main seal leak at the time rather the vibration, but it never hurts to ask someone who has done the business.

If you went solid mount (rubber pucks) on replacement did you notice any extra buzz without the balance chains? I think a plain rubber engine set, with a poly tranny, might well be exactly the way to go for longevity for me - but it kinda depends on what sort of harmonics it sets up around a

2.3l turbo car without a balance chain. Could be murder on electronics, hoses and seals over time.

Hi thought id update you after your earlier posts. The Engine has been opened up and the sprockets on the balance shafts have lost the teeth, dont know why. It is being striped down and checked over, rebuilt with few other bits and bobs being replaced at same time. Hopefuly to run another 140,000. miles Dave