Date: Sun, 25 Sep 2005 07:56:19 GMT
From: David Taylor <>
Subject: Re: Saab 9000 2.3 - strange sound from engine

In article <>, says... > but timing chain noise would disapear after few minutes ? That's the puzzle. When I changed my timing chain, I used all new bits, guides, sprockets, chain, tensioner. When I restarted the car, it sounded fine. Then I lowered the jack and it sounded like yours does. I raised it up again and it still had that intermittent knocking. It's hard to tell how loud yours is over the rest of the engine noise but in my case, I did the screwdriver to the ear trick and it was definitely chain knocking against the timing cover. I took the cover off, the chain was taught. I just didn't understand it and it took a couple of hours of experimentation to find the problem which in the end I found by chance. I was turning the engine over by hand and at one time did it backwards. At this point I heard the chain tensioner ratchet "give" and the chain went slack, turn the engine the other way and it ratcheted back out again. I could repeat this over and over. What was happening was that when the engine started, the tension on the chain was causing the plunger on my NEW tensioner to rotate slightly such that the teeth didnt have a good grip on the ratchet rack and the tensioner would give and go right back in making the chain slack and thus slap with an irregular knocking sound against the top guide in the timing cover. Stop the engine, everything settled and the tensioner would take up the slack which was why it was so hard for me to find, everytime I took the cam cover off, the chain was sitting there nice and taught. So, i'm not suggesting that's what your problem is, just that it sounded like mine! :) Maybe in your case if it is the tensioner, it sorts itself out after a few minutes? Generally sounds that go away after a while are oil pressure related, like hydraulic lifters, it's just that they're usually very regular and not the irregular, louder knocking that you seem to have. David.

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