So, update thus far:

I had the car towed back to LA from San Luis Obispo and Strasse. Many thanks to them. It looks like the failure is the valve spring. My indy shop here has taken the engine out and the valve spring broke as apparently that is also a weak point in the engine.

I'm having all the valve springs replaced and while i'm there, having the head ported and polished.

Hopefully, that's it. Stay tuned.

 

Broken valve spring the best of the worst things that could have gone wrong or the worst of the best things that could have gone wrong.

Not aware valve springs particularly weak in these engines. I've seen far more cars in for worse (mainly IMS failure) than valve springs. In fact the only one I can remember was a 986 Boxster with 65K miles (DD) though I don't know year, but a 986 model that I spotted in with a broken valve spring. Intake valve. Mech. told me driver (woman) takes good care of car, too. But she drives it every day. (I have pics of combustion chambers of the one head cause I was amazed at how "clean" the chambers were.) 'course engine had to come out to remove head. Only one valve spring being replaced though. Others I'm sure were inspected though.

Anyhow, in your case, glad it was not something more serious.

Sincerely,

Macster.

 

Wait, a broken valve spring and no bent valve? That's highly unlikely.

Not saying it cant happen but that would be unusual IMO.

 

Not unusual. Generally the valve spring breaks but doesn't go all to pieces.

There is enough spring action to keep the valve retainer tight and the valve retainer keepers in place and the valve and lifter following the cam lobe profile quite accurately, though the max. revs at which valve float (at least the one with the broken spring) will occur is lower.

If one would keep driving the car and reving engine to near redline eventually -- sooner than later probably -- the valve would float and perhaps kiss the piston. Then you'd have a bent valve provided the valve head didn't break loose and fall into the cylinder. If this happens... oh my.

Sincerely,

Macster.

 

Happened to us on the way to Road America earlier this year and to an unlucky couple at Blackhawk Farms this past weekend.

On our car, spring broke at the base. Would intermidently float the valve, but the keepers were loctited in place by the guy who did our heads, so they stayed in place.