Date: Sat, 13 Nov 2004 16:25:29 GMT From: Dexter J <lamealameadingdongnospamlamelame.org> Subject: Re: changing Timing chain and balance chain
Salutations: On Sat, 13 Nov 2004 08:53:54 GMT, Dave <davetempnospamueyonder.co.uk> wrote: > 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. -- Radio Free Dexterdyne Top Tune o'be-do-da-day Shirley Bassey - Goldfinger http://www.dexterdyne.org/888/073.RAM all tunes - no cookies no subscription no weather no ads no news no phone in - RealAudio 8+ Required - all the Time
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