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Old 04-17-2009, 10:20 PM   #1
Pursuit
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Default Knocking between 2k-3k RPM?

Looking at a steal of a buy on an '05 Saabaru (2.5 N/A) that has a strange knock between 2k & 3k RPM. No noise below, no noise above, runs smooth and pulls fine. Unknown maintenance (trade in). They say it happened suddenly during a test drive, no noise before.

From my searches, I'm optimistically thinking possibly a broken timing belt tensioner?

Anyone run into a RPM range specific knock before?
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Old 04-17-2009, 11:44 PM   #2
watchunglava
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sounds like maybe the previous owner flashed a bad map on your rom.

i would stay away .
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Old 04-18-2009, 01:22 AM   #3
williaty
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They all knock in that range, but you shouldn't be able to hear it.
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Old 04-18-2009, 11:57 AM   #4
yarrgh
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I've run into an RPM dependent knock before. #4 rod bearing was dying. Yours may be completely different, but that's where mine started.
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Old 04-18-2009, 02:44 PM   #5
Marnix
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If an engine has a knocking noise on light throttle at 2500 rpm it's probably a bad con rod bearing.
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Old 04-19-2009, 01:31 PM   #6
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k, first lets clarify... is this audible knock to the driver or knock being heard by the ECU?

If its audible and heard by the driver, something is broken/worn and should be fixed before you buy it. If it's just detected by the ECU, then many other things should be considered... from gas octane and ignition timing, etc etc.
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Old 04-19-2009, 02:54 PM   #7
Back Road Runner
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05? Under warranty?
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Old 04-20-2009, 01:11 PM   #8
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Not under warranty, ~130k miles.

Can hear it, clearly something is broken. They're not interested in fixing it, they're selling it for less than the car's value minus the cost of doing an engine swap. I'm hoping to not have to go that far with it, but for the price am considering it.

Thanks for all the input!
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Old 04-20-2009, 04:50 PM   #9
yarrgh
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search youtube for knock sounds, it may help.
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Old 04-20-2009, 06:13 PM   #10
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Yeah I did the youtube search, the thing that's puzzling me is how it's only knocking in that certain rev range. Everything I've heard is consistent.
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Old 04-20-2009, 06:36 PM   #11
RaceFaceXC
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they wont pull the timing cover and check the tensioner at the least? if the tensioner is worn/broken it could lead to a blown engine at anytime. They must not want to sell this car very bad.
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Old 04-20-2009, 11:59 PM   #12
Audi20Tdriver
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dude.. forget that car.. 130K on an 05?! I just sold my 05 RS for my audi in Feb.. it had 37,500 miles on it. which is about right for 'normal' usage. this sounds like you're looking to buy trouble.
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Old 04-21-2009, 12:29 AM   #13
Jerry Xu
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He says it is a steal, ok?
How do you know it is knock? Are you able to hook up a computer to log for a few minutes to test run it in that range?
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Old 04-21-2009, 07:35 AM   #14
Marnix
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It's audible so you won't need to hook it up to define if something is broken. If the price is right (ie. you can invest in a new shortblock) why not...
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