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Pete, Technician
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Experience:  17 years automotive training and experience.
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Saab 9-3 2.0T: 2001 9-3 turbo 5 speed with knocking noise when

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2001 9-3 turbo 5 speed with knocking noise when accelerating. Gets faster when accelerating and slows when decelerating. No knocking when sitting still at idle. Engine running smooth and gears shift smooth. What could this be?
My name is XXXXX XXXXX I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.

If this occurs in gear or in park/neutral as well this can usually indicate an internal mechanical fault in the engine itself in most cases.This may be a crank shaft rod bearing or main bearing causing this issue and it may only occur under load or when the engine is revved up as I have seen in some cases.I would check the oil level and make sure it is o.k.,if found to be o.k. then next check and see if any shiny flakes of metal are found in the oil in the dipstick or when the oil is drained to see if this is an internal engine problem like a failing bearing.You can in some places also take an oil sample and have it tested to see if there is metal debris found in it.If this is the case then the engine would need further internal inspection to locate the fault to see if it can be repaired or if the engine needs replaced.

If this only occurs while driving the vehicle when the vehicle is moving down the road this may be an internal transmission component at fault causing this here.If this is the case let me know.

Thanks Pete
Customer: replied 3 years ago.



Thanks for your reply, but I think more is needed. In this case it is more the second senario. I can idle and rev the engine with no knocking. The knocking only occurs when driving and becomes more rapid at higher speeds. Sounds like a bump, bump, bump, ... continuously while driving. When I stop, no knocking. The car shifts very smooth through all gears and reverse.

Have you had anything inspected on the vehicle yet for this issue?
Customer: replied 3 years ago.

Not yet. With this being an older vehicle I wanted to try and gain some insight first. Not sure if it is worth repairing...

O.k.,this may be an internal mechanical issue inside the transmission possibly or even a fault with one or more of the axles in the transmission.It may also be an issue with one of the front hub/bearing assemblies.

It is difficult to pinpoint this for sure without seeing and hearing the noise and checking it over so it is best to have it checked over to see if the fault can be located.This would best be done on a hoist/lift and the vehicle run in gear to see if the noise is reproduced then to locate the noise.Some shops offer free inspections so you might see if this can be done to see if the noise can be located for sure.

I hope this has helped and if you need anything else let me know.

Thanks Pete
Customer: replied 3 years ago.

Thanks Pete. Going to seek out an inspection. With either of these senarios would it be safe to drive to the shop or should the vehicle be towed?

Usually with a knocking noise like this this can indicate a component can possibly damage something else in the vehicle or is failing and I usually recommend to not drive it until the fault is located.

Thanks Pete
Pete and 10 other Car Specialists are ready to help you

I am following up with you to see if you still needed help with your question you had asked.If my help didn't satisfy your question please let me know so we can continue.

Thanks Pete
Customer: replied 3 years ago.

Pete, I took your a advice and made an appt to have a mechanic do a free diagnosis of the problem. Thanks.

Your welcome.I hope you can get this resolved with ease.Let me know if you need anything else.

Thanks Pete

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