2004 9-5 with engine knock

[DKMENSA]

My name is Dan and am a newbie to this forum but not to Saabs.
I bought a 2004 9-5 Arc station wagon auto with 114k miles. I bought it with a known 'knocking noise' from engine compartment.
Vehicle was owned by a meticulous one owner and kept the car in great shape with mobile 1 oil changes.
I'm hoping to diagnose and repair( best case )or replace engine(worst case).
Description of knocking noise:
-dies down with higher engine RPM
-dies down when HVAC system is switched to off
-no oil leak or SES light
-seems to be coming form oil pan area(using the screw driver to ear trick)
Next step:
-drop oil pan to see if a rod/bearing is loose

Any one on forum have any thoughts/experience on this noise. possible sources and solutions?
Thanks for your input

[DKMENSA]

here in pictures are the result of trying to rule out a bad rod/main bearing:
- sump/oil pan was surprisingly clean
- i could not feel any looseness in the crank/rod/bearing assy
- no sign of sludge
- no metal chunks in pan



Next steps:
--Pull cam cover and inspect.
--???
Please chime in on next steps

[Mike Brennan]

Take the belt off and see if the knocking stops. Could be a faulty pulley.

[DKMENSA]

Take the belt off and see if the knocking stops. Could be a faulty pulley.

Mike,
Tensioner pulley was replaced along with a new belt. This was the original misdiagnosis that was performed by a mechanic before I bought it from original owner.
Is there any other checks I should do before I reinstall the sump/oilpan?

[Mike Brennan]

"Tensioner pulley was replaced along with a new belt."
Acknowledged.
Now take the belt off and see if the knocking stops. Could be a faulty pulley.

[nordwulf]

That's quite an unusual sound. Besides what Mike mentioned, are you using premium gas (91+)?

[DKMENSA]

Just bought the vehicle so I will be using premium gas. Not sure what the orig. owner used.

[DKMENSA]

[FONT=verdana]I'm leaning towards a cracked flex plate being the culprit

Not sure what could have led to a cracked flexplate, But very happy, to say the least, that it's not the engine.[/FONT]

[FONT=verdana]Any suggestions on trans removal and other parts to replace with tranny out would be appreciated.[/FONT]

[FONT=verdana]Yutube video of flex plate noise:[/FONT]
http://youtu.be/kwHgnpS28Os

[DeviousByNature]

Kind of new around here so I'm not expecting a lot of clout from the get go.
Firstly does the sound lessen or worsen with higher RPMs?
Saab engines are noisy little boogers anyways, most ticking people hear and complain about are all
the directional valves doing there job in you vacuum system lines.
Piston knock 9.5 times out of 10 will worsen mildly to greatly at higher RPMs especially at a slacked or (consistent) higher rpm.
I would look into the timing chain to be honest. Sounds exactly like mine did. Get a copper pipe or any metal hollow tube and try to pin point
which side the noise is coming from by using it like a stethoscope. If its coming from the pully side of the engine I would say timing chain.
I raplaced my balancer chain, timing all the guides and the auto tensioner and the sound was gone, the slack in the chain is slapping the valve cover. If you can rev the engine up and the sound goes away then chances are thats what it is. At higher Rpms centrifugal force causes the chain to expand evenly and eliminates the slap. I loaned my saab to a friend he hit the freeway in paddle mode and ran 50mph in first gear cause he didnt know how to shift it. Slung a piston right through the fron of the block. Had to do a full engine swap.

Was fun stuff.

[DKMENSA]

CONFIRMED!
Replaced the cracked flexplate.
Noise is gone!
$175 new flexplate
$500 labor