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Harsh Valve Knock Under Accelleration
Folks,
Checking out an '83 911 SC yesterday. Had a bit of valve knocking when running in neutral under accelleration. Driving was another story, serious valve knock while under accelleration, dissappearing when running at speed. Something I should be seriously concerned about? Will have a PPI in the next couple of days. Just wondering what would cause the harsh knocking and if it is indicitive of engine rebuild around the corner. Gordo |
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09-22-2002, 03:21 PM
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Navin Johnson
Join Date: Mar 2002
Location: Wantagh, NY
Posts: 8,784
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Valve knock? please explain
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Don't feed the trolls. Don't quote the trolls  http://www.southshoreperformanceny.com '69 911 GT-5 '75 914 GT-3 and others |
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09-22-2002, 03:32 PM
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Formerly bb80sc
Join Date: Aug 2001
Location: Hollywood Beach, CA
Posts: 4,361
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Hmmm, are you sure you are not hearing detonation? What's your timing advance like? What grade of fuel? When was your last valve adjustment?
cheers -Brad 80SC |
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09-22-2002, 03:34 PM
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Registered
Join Date: Jul 2001
Location: Lawrenceville GA 30045
Posts: 7,378
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You might be hearing the after-affects of the dreaded BHS! (Broken Headstud Syndrome). The PPI should include a valve cover removal and inspection for this possible problem, or the mechanic may be able to tell from the symptoms and a test drive. I assume you are having the PPI performed by an experienced Porsche shop?
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Mark '83 SC Targa - since 5/5/2001 '06 911 S Aerokit - from 5/2/2016 to 11/14/2018 '11 911 S w/PDK - from 7/2/2021 to ??? |
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09-22-2002, 04:06 PM
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Registered
Join Date: Sep 2000
Location: Shreveport, La.
Posts: 1,710
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Sounds like more than one headstud. Could be an $8000.00 bargaining chip.
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Robert Stoll 83 911 SC 83 944 |
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09-22-2002, 04:14 PM
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Further Explained
Let me try to clarify a little:
Yes, it sounds like detonation (or valve knock, whatever you want to call it). Could have been an exhaust leak (broken head stud?) but it sounded a little too much like valves. Like the $8000 bargaining chip part. The place wants $6,200 for the car. I guess I could ask them to give me $1,800 and I would take it away (will that work with dealers, I'm willing to try). Just wondered if anyone else had this noise with their car and what repairs were. Thanks, Gordo |
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09-22-2002, 04:39 PM
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Registered
Join Date: Sep 2000
Location: Shreveport, La.
Posts: 1,710
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If the dealer is selling and 83 for $6200.00, they can probably show you which of the headstuds are broken. Sounds like they are bailing.
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Robert Stoll 83 911 SC 83 944 |
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09-22-2002, 04:42 PM
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