Hard knocking sound when engine is cold

[devioustrap]

For the last couple of days when I turn on my 9-5 (and the engine is cold) I get what I can only describe as a rough knocking noise. At first it wasn't too noticible, but when I started the car yesterday it was a very defined loud noise. The noise goes away and the engine appears to run normally as soon as it warms up.

I haven't driven the car since I started it up yesterday as I don't want to do any damange to it. Anyone have any ideas as to what it could be?

[B~P]

not a good sound. read this thread. http://www.saabcentral.com/forums/sh...ghlight=sludge

good luck.

[devioustrap]

I actually spent the last day or so reading that thread and almost completely finished it. However, I'm not hearing an oil pump whine (or a any whine, for that matter) as described in that thread. What I've got definately sounds more like a knock. Is that also a sludge symptom?

I've been doing 5k mile synthetic oil changes since I bought the car (20k miles ago, it's got about 80k on it now) as was hoping I'd be able to avoid the sludge issue. Guess it can't hurt to drop the sump anyway on Monday, since I'll be off due to the holiday.

[B~P]

Originally Posted by devioustrap

Guess it can't hurt to drop the sump anyway on Monday, since I'll be off due to the holiday.

good man.

[MacNoob]

Originally Posted by devioustrap

For the last couple of days when I turn on my 9-5 (and the engine is cold) I get what I can only describe as a rough knocking noise. At first it wasn't too noticible, but when I started the car yesterday it was a very defined loud noise. The noise goes away and the engine appears to run normally as soon as it warms up.

I haven't driven the car since I started it up yesterday as I don't want to do any damange to it. Anyone have any ideas as to what it could be?

Obviously we can't hear your noise. My 9000 had a terrible clacking noise that went away awhile after startup - I noticed the serpentine belt tensioner moving around in time with the noise - replaced the tensioner and all was quiet!