Saab 9000 Timing Chain Replacement

Is there typically enough indication that your timing chain is going to rely on?

Reply to
Valjean
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Sadly - not 100% really.

The timing chain in the modern overhead cam engine is a much more stressed item than in a push rod engine being that it is much longer and generally lighter built. It rocks over timing belts of course - but still not your Dad's Oldsmobile.

So, where you are given specific and considerable warning regarding timing chains in your old Vauxhall or Ford - a timing chain in our application can develop a serious weakness and fail very quickly - most usually when you are showing off the turbo (if so fettled) or burning off some carbon in the 5,000rpm range - if you are spoting a reliable old Bosch LH.

Anyway, it is possible to have a perfectly good timing chain by all rational soundings on Monday - and still - be in the shop Friday with a very seriously damaged engine - and for all kinds of reasons. This is the trade off for exceptional power and fuel economy from what is in essence still a 2.0 or 2.3 liter engine.

Basically, if the body is still good, pull the block every 200,000 miles. Do the chain, seals, gaskets and guides - unless - you are getting a real definable chain lash noise behind the water pump.

But - depending on your particular vintage - you will likely have to drop the serp belt to hear chain lash and that may change the loading on the timing chain depending on the condition of the devices it powers. So - most folks start repairing the pumps and alternators around 150,000 and see what develops.

I went to a very high grade Moly synthetic oil at 113,000, replaced a couple of dodgey hoses around the turbo and topped up with BarsLeak (the old walnut kind) this winter.

Reply to
Dexter J

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