Saab 9000 2.3 - strange sound from engine

Welcome brother Marek - my best guess(s) is that you are hearing the injectors clicking (it goes away after it warms up) or BPC unit on the rad starting to wear out.

Although, frankly, I'm in the middle of a noise hunt too and it could be one of several things. Balancer chain getting a little older, sticky valves (sludge in the oil system), alternator bearing starting to pack up, water pump starting to erode, belt tensioner starting to pack up, power steering fluid in need of a change, AirCo clutch sticking. Just simple leak somewhere in the exhaust manifold, cat or joints.

Your best bet is to get a mechanics stethoscope with a probe and carefully try to track it down to source, I keep one in the tool kit actually. Hit saabnet.com 9000 bulletin board and search on component/noise for further detail as you go.

Given it's a new/used car to you - it is worth being very careful to check everything for correct torque, gap, resistance and flow. Not everyone is above leaving something for the next owner and it is good practice to try to fix things in the 9000 *before* they fail outright and destroy the more expensive complete component or system they are attached to.

The upside of this approach (and the 9000 line in general) is that it can be relatively inexpensive to fix a smaller problem in a given component before it fails and the fix will often last the lifetime of the car in your hands.

Adek bräkte:

I like this sound:

Sounds more like timing chain slap against the top of the cam cover to me as it's too inconsistent to be a hydraulic lifter. Assuming it's that sound that you're referring to.

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.

Wow.. thank your fot great tip.. but how have you finally fixed it ? Replaced tensioner ?

Yes, I put the old tensioner back on instead of the new faulty one.