Were you on probation? I got to S/Storm in Sept and left early April after the 'wrap up'. Lovely place.
Did you do a top end at the time, only seems rational.
I've been lucky I guess, only owned it for a year or so but it has seen 10k in that time and I suspect I'll keep at that rate. I took it to a shop for a 'should I rebuild and when' check and after the leak down he told me to come back in 5 years and just 'drive it'.

I got it from a guy who was going to put it in his 74 chassis.

He got it from an original wrecked car from PartsHeaven that had 87K miles in 1999! He had the motor sitting on a crate for 4 years, oiling and turning every year.

I bought it and had it on a stand for another 10 years, oiling and turning every 6 months, before putting it in my 914-6!

I cleaned everything up, did a leak down, resealed and replaced the broken head studs before I put it in the 914! Now it runs great!!




http://forums.pelicanparts.com/uploa...1359775533.jpg

Sometime prior to 156k on my 82SC: 1 broken stud, two in the process of breaking (as in fractured). Replaced all lower studs with steel. Now my bank account is broken.

Jeffs....Nice, in that center location it must balance nicely...what does it weigh in at?
I've been on a weight loss program and have the SC @ 2390 less fuel...still working at that.

It is sitting at about 2200 with everything original (except the early bumpers) and the 3.0L up grade! It is a rocket!!! If I put it on a diet I could get it down to about 1970 without much work!

I don't even use 1st gear! I am building a trans that will spread the torque out a bit more and match the motor!

dilivar studs
 

Just removed the exhaust valve covers and ALL the dilivar studs were broken.
1980 SC that I bought from the original owners son.
He inherited it after Mom passed and could never get it running right. He sold it to me ( we've been friends for 10 years). Has 67,000 miles and I couldn't get it to run right either.
Grandson and I dropped the engine Saturday and that's when the studs hit the fan.....so to speak.
My question is how rare is it to have ALL the dilivar studs broken?
I was changing to Webers and SSI's but looks like it's a good time to do a cam change, top end job and whatever else crops up.
I need a beer or 3.
Has anyone else noticed that their beer consumption has increased after buying a Porsche?????

How did you test it?
 

Reiver,

How did you confirm that the lower cylinder head studs are steel and not Dilavar? The cylinder head studs are not that accessible and are blocked/covered by the metal cooling tin and barrel nut/s. Thanks.

Tony

Why does Porsche continue to use fully threaded dilavar studs?

Stupid question : any identifiable symptoms ??

The rest of the story...this excerpt is from prepared text for the 9th Edition of my book.

Cylinder Head Studs
1977. Porsche was well aware of the problems associated with the 2.7 liter engine with its pulled cylinder head retaining studs following a repair that required cylinder head removal; sometimes the studs would pull without apparent reason. Porsche knew about thermal expansion, and had used, since the early ‘70s, in racing engines, a cylinder head stud made from an alloy called dilavar, while all street engines were assembled with steel head studs. Dilavar studs, first used in 930 Turbo Carrera engines, were found to have roughly the same thermal expansion properties as both aluminum and magnesium, which, in theory, would greatly reduce head stud stress at higher engine temperatures. It’s been written that steel studs, on the other hand, have an expansion rate roughly half that of the aluminum cylinders and cylinder heads that they hold together, which put extreme loads on the crankcase and the studs themselves. Dilavar studs, a non-magnetic steel alloy, found their way into 911S production part way into the ’77 year, but the studs were only used in the bottom twelve, exhaust side, positions (each 911 engine uses 24 studs, 4 per cylinder head).

A thoroughly tested no-brainer, or an experiment, I don’t think that anyone knows the answer to that except for a select few people at Porsche. The first dilavar studs were a shiny, brushed finish, similar to many modern kitchen cabinet and drawer pulls, with a color closer to silver than to light gold. Their purpose was to stabilize cylinder head torque through the temperature range that the typical 911 engine ran at. I’m sure that the factory hoped that Dilavar studs would also be the cure for pulled head studs in magnesium engine cases. Because the thermal expansion rate between early steel studs, and the alloys that they secured, were quite different, the change was made.

1980. The first improvement to dilavar studs was made for 1980 SCs, which proved that Porsche was committed to their use. The stud changed in appearance, to an almost jewelry gold finish. For this design change to happen so early into the use of dilavar, Porsche must have seen, and not liked, corrosive activity on the first generation stud. Factory literature states that Porsche’s original philosophy of using twelve upper studs made of conventional steel, and twelve lower studs made of Dilavar remained consistent beyond the 1980 models. At some point Dilavar studs were again changed, and the newer version was coated with a gloss-black paint-like substance obviously designed to withstand corrosion. This change was thought to have been made during 1981 production, or at the outset of the 1982 build run.

OK, you’ve read the first part of this chapter and are probably wondering what the big deal is. Well, if you own a 1977-81 SC the subject matter above could easily make you about $3K poorer. Head studs break. Some more often than others, but mostly the problem occurs with the uncoated, early studs, followed by the second generation, also uncoated, studs. The studs break about two inches from the end where the head nut screws on; they are obviously susceptible to corrosion at that point.

A fastener such as a stud, or bolt, is under constant stress, from the time that it is tightened until the time that it’s loosened. The act of applying torque to a fastener is the actual stretching of, in this case, the stud. Enter corrosion, which attacks where it can, and begins to eat away at the metal. Remember, dilavar is a steel alloy, it is not immune to corrosion, actually far from it. At some point in its life, a corroded head stud will snap at its weakest point, and will no longer provide the fastened strength that a cylinder head requires at each of four corners.

Head studs break on low mileage cars; perhaps more often than on high mileage cars. “How can that be?” one might ask. No one knows the answer, but I know it to be true. I also know that it doesn’t happen to all cars, maybe even less than ten percent of each involved year. My shop replaced head studs on far more cars with less than 50K miles on the odometer, than with more than 100K miles. Surprise, the cars that can be considered garage queens, and are obviously the most desirable to find and buy, are the ones that have this potentially expensive time bomb lurking in the engine bay.

FAQs:
“How does one know when a head stud is broken?” All 911s built between 1978 and 1989 have the same maintenance requirement for what is normally referred to as a major service – typically required at about 15,000 miles. That service consists of a valve adjustment, oil and filter change, engine tune up and other items. In order to perform a valve adjustment, the valve covers, aka rocker covers or rocker arm covers, must be removed. There are four covers per engine, and are usually referred to as intake (upper) covers and exhaust (lower) covers. During removal of the lower covers I have been hit on the foot by a two inch long piece of a head stud, with the cylinder head retaining nut still on it. Sometimes the broken piece will fall out; sometimes it will hide in a recess in the camshaft housing casting. A normal major service inspection should include, especially on high-risk cars, a visual to verify that all of the studs/nuts are intact.

“What is the immediate symptom?” Usually there is no symptom, especially on conservatively used, commuter or weekend cars. I’m aware of cars that have been driven thousands of miles after a broken head stud was diagnosed, with no negative result.

“When does stud replacement become something more expensive?” If one or more broken studs are discovered during a major service and the needed repair is ignored, at some point a corner of a cylinder head, usually the corner with the broken stud, will work loose enough to leak combustion (the gases that are supposed to leave the combustion chamber via the exhaust valve/port). From the very moment exhaust gases begin to leak out between the cylinder and cylinder head the process of erosion begins. Eventually a cylinder, possibly even a cylinder head, will be damaged beyond repair.

“Is there a symptom when it’s almost too late to do the basic stud replacement without extra cost?” Yes, the driver will hear a distinct and rapid “pop, pop, pop…” during acceleration; louder with a cold engine than a warm engine.

“Is there any way to ascertain the presence of a broken stud without hearing the popping noise, or removing the valve covers?” With the car raised up enough to see the bottom of the engine, a flashlight examination can be done of the areas where the cylinders and cylinder heads join. Those areas should be dry and clean. If there is a black, crusty layer that appears to be burned oil, there is a chance that the engine has one or more broken head studs where the buildup is the heaviest. However, a broken head stud is not always responsible for this condition, sometimes it is from a tiny imperfection in a machined surface, and no immediate repair is required.

“If my engine has broken studs can the job be done so the repaired engine is a long-life unit?” Going by everything that is known today, the current generation of cylinder head studs, developed for the 993, should be trouble free for at least the service life of the engine that they’re in.

“If my engine was originally fitted with steel upper studs, and Dilavar lower studs, should all 24 studs be updated to Dilavar?” Porsche must have done temperature analysis regarding the required expansion of the upper and lower studs, but I’ve not seen a technical bulletin advising the correct way to handle this. My shop found evidence of corrosion on original, steel upper studs, so our policy was to install 24 new Dilavar studs on those engines. Follow up inspections showed no adverse results regarding those repairs.

“Are the black-coated generation of studs, used since 1981/82, the latest generation Dilavar?” No, Porsche developed a new Dilavar stud for 993 models (1995-1998), and 993 studs should be used for all repairs.

“Can anyone do this repair?” Usually you’re better off with a seasoned professional when 911 engine repairs are needed, an assortment of special tools are needed to perform stud replacement, and it always helps for your technician to have a set of factory repair manuals on hand as well. There is no really good answer for this question, because there are probably better DIYers out there than the mechanic at the local dealer. My advice is to do your homework, ask every question that you can think of, get referrals, and then check out the shop you’re thinking of using. When you get there and you don’t see anything but a clapped-out 924 and a bunch of 3-series BMWs, rethink your choice.

On reading this, I just went back through the service records from the PO, and they show 12 Cylinder head studs replaced about 5K ago... don't say anything about Dilavar, Steel, or otherwise... interesting... and when I look under the car, they seem clean, no burned oil, etc...

One question.... Harley Davidson and the race bikes using Harley motors, Buell, use similar studs, with no issues... I believe they are just steel, and work just fine... any reason for the introduction of Dilavar on Porsche?

300K on 1980sc
 

Closing in on 300,000 miles.
No Pop Off Valve and original non pressure fed chain tensioners.

Is my car an anomaly ? Or some freak Porsche on steroid oil ?

I purchased my car from a friend and original owner who drove it often but not in the rain or snow. It runs perfectly. and no I did not get a PPi and I know that is not recommended but I was familiar with the car and the price was reasonable.

The original engine has never been opened and I have all the maintenance records.
(It did have a new clutch installed)
The car was serviced by the same independent Porsche mechanic for the last 25 years.

I will be doing my first valve adjustment and being a VW bug & bus guy I will do the
traditional method as opposed to the backside. (purchased Wayne's books and Bentley as well as Andersen's book and the Zimmerman book)

After reading these boards for the past four months I have this fear that when I remove my valve covers I am going to have all this broken hardware raining down on me and clanking all over the garage concrete floor. LOL
(actually that would not be very amusing)

I had bought the car this December for a very reasonable $8,000 and it was running great so I figured worst case scenario I eventually get to rebuild a Porsche Engine.
Pretty cool. But I still was and am hoping to get a couple of seasons of weekend driving in before a rebuild.

With any luck I will not find any broken studs.
I have read where owners have continued to drive with the engine in this compromised condition for awhile albeit probably not advisable.

Stay tuned……….I am going in this week. (cover me)
I will give a full report with photos.

Plan is to get a baseline from which to work.
http://forums.pelicanparts.com/uploa...1364860851.jpg
The Petrol Blue Monster

250000km
No pop off valve and all original studs...

Seems like the sky is not falling after all :)

hard to imagine the other 12 broke in 5 k mi.
Dilivar is supposed to have an expansion rate similar to the aluminum of the crankcase and cylinders .so it doesn,t stress the block threads when heated up

Congratulations!!!!!!!
 

But how did you know that you still have the original Dilavar studs on your engine? Did you own the car since new? The reason I asked, is that I found several SC's that the owners did not know that they have all-steel cylinder head studs (lower) already.
Thanks.

Tony

We are 3 for 3 for broken head studs on 3.0 engines... I think we had one with two broken, one with three, and one with four if I recall correctly. All lower ones. All engines with 80,000 to 120,000 miles.

I figure by the time the engine gets to me, I'd better pull the lower valve covers and check because my odds are pretty darned hard to beat. :D

angela