Bought this '83SC earlier this year. The PO put about 20k miles on it in 10 years. I bought it at 110k and I just turned over 117k today. It didn't have any broken head studs at 98k as reported by a Porsche dealership invoice. I removed the valve covers last week to have a look see and found the lower rear most stud on #4 was broken. The barrel nut and about 2" of stud were sitting in the head where the stud hole is. I bought this car with a leaky #3 hoping it was carbon under the valve (I paid a lower price because of this, and knew it going in.) A couple months ago it started making a burbling sound on launch, only under load. I thought it might be an exhaust leak, as it only happens between 2-3k rpm then goes away. But the last couple weeks its gotten worse. I had a very knowledgeable Porsche mechanic do a leakdown a couple weeks ago and here's what we found. We put new NGK plugs in at the same time.
Comp Leak
#1 180 6.5%
#2 185 5%
#3 170 31%
#4 165 13% (this is the one with broken stud)
#5 170 9%
#6 182 ? (we didn't bother doing the leakdown on this one based on good compression)
Today I went for what I thought might be my last drive of the year and the "paddle wheel" burbling sounds was worse than ever. I've read this is what a cylinder with a broken head stud sounds like. I'm also not experienced enough to know if its simply one of the gaskets in the cat or header going south. Some of those areas are pretty crusty and rusty. I'm planning on taking this in to my mechanic this week, but he also encourages me to post here. I'm the mechanical type, and want to work on this car as much possible, not only because it interests me, but also to save money obviously.
Probably hard to hear, but I made a little recording this afternoon. Its audible right at the beginning of the video. It makes the sound the "best" in second gear at around 20mph hitting the pedal at 2000rpm.
https://www.youtube.com/watch?v=WSDi6R5vsdY
This is my first 911, and I'm smitten with the car. It's unlike anything I've ever driven and I can't honestly see not owning one for the rest of my life. I was banking on a rebuild at some point, and had hoped to do it myself (I've built a 1776cc VW engine from scratch, so I've got at least some experience) but parking the car for a year or two while I gather parts and do the rebuild right (along with all the other stuff that needs attention) is giving me pause at this point. One summer of driving and I'm already dead in the water? Ugh. Not a fun thought.
