Quote:
Originally Posted by RPV911
Also a note, everything runs pretty cool. I mean it barely gets past the second hash mark on the oil temp. Does that matter at all?
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Don't believe so -- the heat issue I referenced ONLY affects the valve itself (the increased separation between the worn valve guide and the valve itself reduces heat transfer from the valve - which is exposed to exploding fuel in the cylinder - and lets the valve get hotter than it otherwise should)
Things you should be looking for are:
a) fouled plug(s) (pull all you spark plugs and post a picture of them -- note which cylinders each plug comes from using the firing order diagram sticker isn your trunk)
b) oil smoke in exhaust during deceleration -- worn valve guides will allow oil to be sucked between the valve and the guide by the vacuum produced during deceleration. Unfortunately, a well functioning catalytic converter will burn most of this oil smoke away, making this hard to detect
c) valve noise after adjustment -- while 911 valves can get noisy, they should be pretty quiet after being adjusted to spec - when properly adjusted valves are noisy, its a good sign that the valve guides are worn. Per Porsche guru Bruce Anderson, "If the valves are noisy you should have your mechanic check the valves for valve guide wear. You can check the valve guide wear by pushing the valves from side to side with a screw driver with the valve just lifted off of the seat a few millimeters (about 10 mm). You can actually judge how worn the guides are with this method."
Smoke at startup is generally NOT a sign of worn valve guides, instead, it's generally caused by the oil remaining in our cars' dry sump setup leaking past piston rings and into the combustion chamber -- I've found that if, before I shut it off, I let my 86 targa's engine idle until the oil level gauge on the dash rises to register oil level (around 5-10 seconds), I'm giving the oil pump a chance to evacuate the oil from the sump into the oil tank and eliminate/minimize smoke at startup.
Finally, this problem is unique to 3.2 Carrera engines, which throughout their production, used different valve guide material (and different valve guide seals) than other 911 engines. There are a number of theories as to why only some engines are affected, but the only way to resolve a known worn valve guide issue is through a top end rebuild. Did mine at 500 miles per quart with a greasy looking plug when I had 90k on engine. At 180k, I'm still getting around 2k miles per quart.