Knock in only in 4th between 30-40mph???!?!
01-14-2008, 02:08 PM
#1
Staging Lane
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Knock in only in 4th between 30-40mph???!?! Like stated in the title, my engine knocks only in 4th gear between 30 and 40. Searched to no avail. It's not too loud, but loud enough to be heard from the cabin. Seems to be getting progressively worse, and occasionally heard in 2nd. Runs well, pulls hard, no issues.
99 M6 Formula, 96,xxx miles, lid only, newer plugs, new wires (all attached correctly), occasional spirited driving but has never seen the track, taken care of.
I pulled a 3-2 shift over a year ago, but never saw a loss in performance, and never heard a peep. I don't suspect that this is related but maybe someone smarter than me does.
My first guess is a lifter, or something valvetrain related...
I am completely stumped, please help.
Thanks for reading.
99 M6 Formula, 96,xxx miles, lid only, newer plugs, new wires (all attached correctly), occasional spirited driving but has never seen the track, taken care of.
I pulled a 3-2 shift over a year ago, but never saw a loss in performance, and never heard a peep. I don't suspect that this is related but maybe someone smarter than me does.
My first guess is a lifter, or something valvetrain related...
I am completely stumped, please help.
Thanks for reading.
01-16-2008, 09:29 PM
#4
Staging Lane
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I'd call it more of a knock. Definitely not a bottom end knock sound though. Could be an exhaust leak but I would expect to hear it through all gears, right? It's difficult to pinpoint because I can only hear it when I'm driving, so I can't get under there to say more specifically what it is. Excuse my ignorance, but what's the best way to check for an exhaust leak. Thanks for the reply.
01-17-2008, 12:43 AM
#5
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Carbon deposits? Lean cylinder(clogged injector)? Bad fuel?
Old school exhaust leak checker= lit cigarette. Move it around flanges and it will glow brighter when blown on by leak.
Old school exhaust leak checker= lit cigarette. Move it around flanges and it will glow brighter when blown on by leak.
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01-18-2008, 08:57 AM
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Staging Lane
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I wouldn't think carbon deposits or clogged injector as I've cleaned the engine les than 10,000 ago (not "seafoam" but something similar, by Valvoline if I remember correctly). I always pump premium, Only been drinking Mobil since I've owned it.
kw's01z28 - not sure about going up a hill, pretty flat here in MI.
98 WS6 - lol, it's sad but i think you've come the closest so far....
kw's01z28 - not sure about going up a hill, pretty flat here in MI.
98 WS6 - lol, it's sad but i think you've come the closest so far....
