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

Valve knock? please explain

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

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?

Sounds like more than one headstud. Could be an $8000.00 bargaining chip.

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

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.