Timing / balance chains

[dave225]

I think I've got the usual timing chain issue - a slight rattle when cold for about 2 mins, then quiet.
84k miles on the std oil change schedule.
Can anyone advise whether that is likely to be just a stretched timing chain and could be fixed by winding on a new one?
Has anyone done that?
I'll get the full kit if necessary and change it all over for peace of mind. Has anyone done that? Is the PFS kit OK?
Can this job be done without lifting the engine out? or lifting the head?
Any advice / experience appreciated.
Thanks
Dave

[mikeloadsasaabs]

I'd leave it alone. If it's only a slight rattle, it'll last for years - timing chains don't suddenly snap like belts. My Aero is on 185,000 on the original chain, I don't even bother listening for the noise! My old 9000i at 202,000 miles sounded like a few metal bolts in a cement mixer first thing in the mornings, but it still ran fine!

[Audax]

If you do replace a chain you need to replace the whole lot really. If you don't then you can't be certain of the state of the balance shaft chain and gears which can be more of a problem than the main chain. It can be done with the engine in the car but when putting the timing cover back it's perfectly possible to damage the head gasket which means even more resultant work. I'd be tempted to leave alone.

[TomPaine]

Aye, when you say "the usual", is it that common? (My first 9-5, now with my brother, is at c194k.)

[dave225]

"Usual" is because Saab started selling a repair kit under one part number - a sure sign that something is amiss. This has been going on since the same engine was in the 9000, which is a bit of a worry.  Maybe its to do with extended oil change intervals these days (18k miles on the 9-5). You can't hear it when the bonnet is down, so it could well be more common than we think.

[Audax]

Having worked in a specialist, timing chain replacements were really rather rare. We did more engine swaps due to sludge (and they weren't that common in recent years after sump drops and the later breather kit) than chains. Chains will get noisy from 150k onwards but by then most people decide to chance it as they feel that £800 for timing chains on a car worth not much more is too much money. The most common cause of us fitting a timing chain kit was when we were fitting a secondhand engine that had died due to sludge.

[harryO]

84K seems rather low for chain issues. Are you sure it is coming from the timing chain and not the big ends? Very difficult to detect such noises coming from a running engine - I speak from experience! Have you done the sump drop?

[Norfolk Jim]

Timing chains do snap! My son had it sadly happen on a 'P' reg 9k aero with fully documented service history and 145k on clock. The engine was actually very very quiet and an auto.

He was accelerating on bypass when loud bang and bits flying out from under car - there was a hole on front of block at bottom you could put your fist in!

It was just that 0.01% - previous owner was also devastated as they'd been meticulous with maintenance.

Wise to be cautious but not paranoid. Just have it properly checked and as harry say's check sump

[phoenix]

Mine is still pretty quiet at getting on for 156k. Oil changes since I've had it (since 80k) have been every 6-7000. Sump has been dropped and it's had the latest PCV.

I am contemplating a wind in chain replacement as a precautionary measure. The way I see it is this: as the chain wears it becomes more sloppy. This in turn causes an accelerated wear of the other components. Change the chain before it becomes too bad and you increase the service life of the others.

On our old C900i I did a wind in chain replacement at around 210k. The engine was much quieter and smother afterwards.

[Audax]

The issue with that is every time I've seen an engine pulled apart is that the bits that wear are the sprockets for the balance shaft chain where in some cases they were pretty much no longer there.

[dave225]

Audax - does that observation about badly worn balance shaft gears apply to 9-5 B235 engines too?

Given the rain and my current lack of garage, I'll start by lifting the cam cover and see what things look like. I know you can't see much from there but presumably the top guide (which I believe is on the cam cover??) can be seen. Can the tensioner be seen from there? Can I see if it's extended too much?

I've only had it 2 wks and assumed the sludge/sump issues had all gone away by the 2005 model year?
My real disspointment these days is the factory oil change intervals, clearly set by accountants. Mine is at 84k and 6 years and has only had 5 lots of oil!! (6 if you count the one I did last week).

[Audax]

Audax - does that observation about badly worn balance shaft gears apply to 9-5 B235 engines too?

Yes it does and apply to the B205, B235, B234 and B204, although to what extent I can't be certain. Many were probably happily running even with wear on those sprockets. Anyhow, you can remove the tensioner to measure the gap the procedure is in the Saab workshop information system or the Haynes book of lies, or i'm sure that there are guides online.

As for sludge, it was very much reduced by 2005 but to a lesser degree it can happen to any 9-5 engine. Factory oil change intervals are probably not set by accountants btw, they're more set by the man in the street who doesn't want to spend any money on maintenance with a car and basically equates maintenance to repairs... 

[dave225]

Is the WIS the CD you can buy online in the usual places online? 

[harryO]

I would confirm what Audax is saying about the sprockets on the balance shaft mechanism. Normally affects engines at about 100k miles. First signs are very small pieces of metal in the old oil after an oil change. I soldered a 12v halogen bulb onto a pair of wires are dropped it down into the well of the timing chain to look at mine.

[phoenix]

So, assuming one wanted to do the job "properly" on a DIY basis, how much is realistically achievable in situ and what would we be looking at as a shopping list. Does it make it easier to bite the bullet and do the HG at the same time?