Broken Head Stud - Just Replace Studs???
 

With a 3.0 with a broken head stud is it possible just to change the head studs and be good again?

Once the head stud breaks how likely is it that the head, cylinder or case may become "cut" by escaping gases? Is it likely the head, piston or cylinder could be warped or damaged by running with a broken stud? When you're replacing the studs if they thread out of the case properly is it necessary to do thread inserts on a 3.0 like they need to do on 2.7s?

I need to decided if the cheap route is smart or even feasible.

Thank you

From everything I have read on this forum on this issue I believe at a minimum you are pulling and disassembling the top end of the engine to inspect the severity of the damage to the stud hole in the case and the case and cylinder head mating surfaces from escaping gases. Then it's decision time on the course of action. Thread inserts I think depends on what damage there is to the case. Lots of great experts here.

Then there's the slippery slope of while I'm in there because I have the engine apart ... :).

4 years ago my '78 3.0 engine with 82,000 miles had one broken stud. I went in with all intentions of just replacing what was broken.
Then I found bad cam lobes and broke some rings as it came apart.
Heads were good and so was most everything else. Added oil fed tensioners and new chain ramps and a few other bits and pieces. And of course replaced the bottom row of head studs.

So, new lower head studs, new (used) cams, and new rings were the minimum for mine. I felt better with adding the chain ramps and pressure fed tensioners.

You really won't know until you get inside as to what may need to be done.

No case inserts needed on aluminum cases. Most repairs I've done did not need any head or cylinder repairs on their mating surfaces, since they were caught early.

Do a valve job while in there.

Only if you need it. The 3.0's aren't prone to bad guides like the 3.2's are.
I only need to add a quart of oil every 1500-2000 miles. And that is with re-ringing Alusils!!!

Of course one would inspect the heads, seats and valves. Not doing so would be not be smart.

I had a broken head stud on my '82 SC with 42K miles. I decided to go the "cheap way" and had only the lower studs replaced with new steel studs. Being frugal and new to Porsches at the time, I even pulled the motor and delivered it to my local shop for the work. I spent about $6K only replacing the wear parts (clutch, seals, studs, stock tensioners etc...). Lucky for me, the heads, cams and other hard parts were fine. I learned quickly, there really isn't such thing as a cheap way.

I agree with others, you're best to inspect and replace whats needed when you're in there. If you want to save money, just don't go crazy with race quality parts - OEM stuff is just fine for a street car.

I am in the middle of this right now. here are my recent facts.

Engine has 25,000km on it .

apart to replace broken head studs, one broken but two more broke on disassembly.

Heads came back from machine shop cleaned and new seals requiring zero additional work.
Clutch is only at 25% wear.

I am replacing all seals and chain ramps.

A couple of lobs on cam were worn so had a 964 cam grind since I was doing work on them anyway.
As it turns out I will spend more money on the gear box replacing first and second gear synchros, bands and stop blocks since I have it out.

Having recently gone through this on my 3.2 I'd say order your studs and while you're waiting, disassemble the engine and inspect. If you see no noticeable problems and didn't have any issues put the new studs in and drive it. That's what I did on my 3.2. I guess you have to decide between cost and benefit and the main factor to me would be mileage on the engine.

Just talking.

Did they break in the middle of the shaft? Was there a "pop" or just a ping? They were probably on their way out.

I found an exhaust stud nut when I pulled off the valve cover in the 90's. Plop it went, into the oil bucket.

Called the local Porsche dealer to ask torque spec. Stud looked perfectly straight and intact to me. Service manager asked me, "Doooood, are you sitting down"?...............

Ramps and chains, valve job, seals. $2,500 in parts and machine work (1997). Raceware studs and nuts. $500 for 24 back then. Gotta be $4k now, plus the special tools.

Probably 150 hours reading and wrenching. 60k on car. Bores, ring end-gaps and lands were well within tolerance. So much work for a 911 noob. Lots of "walking away" Extremely satisfying project.

I do remember torquing the cam towers - the Bruce Anderson's book notes to spin the cam (nothing attached) as you go around the tedious bolt circle to make sure it does not bind. I ended up doing it in five ft lb increments as it did bind with larger increments.

Dang, a 2012 Mustang GT sounds pretty good to me!