1983 911SC with Broken Head Studs

[p911sc]

I am a new member to the Porsche Family. And soon to be one that is sleeping on the sofa.

I purchased a 1983 911sc in December, 2005. The car has a pretty good service record and had 130,000 miles. Prior to the purchase, I checked around and found a Porsche mechanic that came under good reference from several friends and I am happy with them. I had a pretty thorough PPI performed on the car, which checked out well, with the exception of an oil leak at the base gasket of the #6 cylinder. The mechanic suggested that I have the seller correct the problem prior to purchase or reduce the sale price of the car. The seller paid my mechanic to correct the problem. From what I understand this involved removal of the cylinders and heads on the #6 side and replacement of the gasket, and rebolt and torqing of the cylinders and heads on this side (forgive me, I'm not much of a mechanic). The seller paid $4,000 for this work along with some other items identified in the PPI.

I asked the mechanic about the condition of the head studs (thanks to previous postings on this web site). In addition to torqing the studs on the #6 side of the engine, he checked torque on each of the head studs on the other bank of 3. Everything seemed fine.....until today. I took the car into the mechanic with a new popping/clapping sound from the exhaust. Interestingly the sounds was only noticeable in 2nd gear. He inspected the car and discovered 3 broken head studs (2 on the one side of the engine and 1 on the other). It has only been 3-1/2 months since the PPI and purchase and I have only put 1,200 miles on the car. Prior to purchase, I had always known that this issue could be a problem and rear its head at some time in the future. 3-1/2 months is not what I expected. Also, I should note that I really haven't pushed the car very hard, typically shifting at 4500 rpm. I was just surprised?? Is this how this problem typically occurs? When I have the work done, should I have all of the studs replaced? Dilavar? Steel? Is this a once in a 60,000 mile issue?

Any advice would be most appreciated.
Rick

[1fastredsc]

Well if you use the new dilavars you'll see them last longer than 60k, they are much improved over the older design (been redesigned quite a few times). However the general consensuse on this board is replacing them with steel, or going to aftermarket (arp ,supertec ,raceware). I got a killer deal on a new set of dilavar on my rebuild so i took it. 100k miles is a long time for someone who like to tinker (chances are i'll crack open the engine before it breaks for some stupid reason or another). In your case i think it's more of a personal call. Steel is cheap and doesn't break, but also doesn't have the thermal expansion properties of aluminum. As i said, your call.

[Jim Sims]

"The seller paid $4,000 for this work along with some other items identified in the PPI."

I hope for that much money the transmission was rebuilt as part of the deal!

There's a way to replace base gaskets and studs without separating the heads and the cam towers; from the bill it appears this mechanic doesn't use that approach.

Steel or Dilavar will work. If it were my SC I'd go with the new Dilavar but there are people who refuse to use it.

[Eagledriver]

I don't know if you have any recourse but it seems unlikely that 3 studs would break in such a short time. I also don't understand a "reputable" mechanic taking one of these engines that far down and not replacing the bottom studs (at least on the side he had apart).

You have to replace all the studs on the bottom row. I recommend steel. You should be able to get used steel studs or a new set. I used old ones that my machine shop had from previous rebuilds.

Where are you located. Maybe we can recommend a good shop. You can also attempt this job yourself if you are so inclined.

-Andy

[john walker's workshop]

all the studs could have been replaced for about $2000 when it was apart. hopefully something worthwhile was repaired for $4K.

[p911sc]

Wow. Lot's of good information.

Nothing was done with the 915 transmission, though that would have been nice. Shifting is a little notchy but still pretty good and feels even better when car is warmed up.

I am located in Valley Forge, PA. Any suggestions on shops would be most appreciated. Also, when they tear down and rebuild, it sounds like this will last me for a good while. Is there any additional work that you would recommend at the same time. I know that is a general question but are there any known areas of problem with the SCs? Valve guides? Rings? etc. Compression and leakdown tests were pretty good when I bought.

Here's the big question:
How difficult is the job? Any special tools required asside from a motor stand. I did check the rebuild section of Pelican under tools and didn't see anything too specialized. Am pretty good with my hands but have never done anything like this mechanically, though I have friends that are mechanics on other cars...Doable or am I dreaming?
Rick

[Groesbeck Hurricane]

Some of the guys in PA should chip in, but I question what was done for $4K. You can do this yourself, the board will help. If you decide to go the route of paying someone to work on your vehicle, I'd go to a different shop. I could be very wrong (I'm overdue at being wrong today so this might be the time) but I have a poor feeling about your current shop.

Oh, and enjoy the couch! I don't get that lucky. I'm usually sent out back to sleep with the horses in their barns...

[Jim Sims]

Do you know where the stud broke along it's length?

Off the top of my head; besides common metric hand tools at least the following are needed to replace case to head studs: Floor jack and two jack stands, wheel chocks, oil line wrenches, dial indicator and holder, 80-1/2 on cam shaft holder tool, 3/8" and 1/2" drive torque wrenches, Sears Craftsman cam type stud remover, Snap-On stud remover/installer holder with 10 mm collet, 10 mm thread chasing tap, and ring compressor.

[p911sc]

Thanks for the info on the tools. I don't know where the break occurred.

I did speak with the mechanic an hour ago. The studs that are damaged are the #2, 4 & 5 lowers. His price for the work is $6,000. This is for 24 dilivar studs, new upper and lower gaskets, headnuts, and washers. From the other posts that I have read, this seems high. What should it cost? Start to finish...

If I go for a second opinion, what is the likelihood of damaging other engine components (heads, etc.) by driving around with the broken studs? Also, would there be any noticeable signs if the situation gets worse.

Suggestions from PA members on good shops for a second opinion would be helfpul.
Rick

[Jim Sims]

$6,000!

Seems like about twice as much as it should cost.

One can buy the tools I listed for between $800 and $1000 depending upon quality.

As long as there is only one stud broken per cylinder you likely have a few more miles left to drive it to other shops.

If it gets worse you will hear more noise.

[Jim Sims]

Pelican Parts prices:

24 Nuts and 24 washers (unless these are in bad condition they can be reused): $138

24 OEM steel studs: $270

or 24 Dilavar OEM (993) studs: $492

Gasket kit: $232

[p911sc]

I'm starting to see what you all mean.

Monday I am going to call around for some more estimates.

I haven't yet given up on the idea of doing the work myself.

Thank you all for the input. Its a painful situation but great to have a support network.
Rick :-)

P.S. I have a few other names of shops but am looking for references if anyone has a suggestion.

[lindemans]

It seems that the studs that were not replaced but were re-torqued in the rebuild have all snapped now....

[Eagledriver]

I found the best way to remove the studs on my engine was to weld nuts on the end of them. The welding heated up the studs enough to melt the loctite and of course they were easy to turn with nuts welded on them!

You don't need to touch the top row of studs. I used to ask if anyone had ever heard of a steel stud breaking. I don't ask anymore because one guy did reply that he had seen it. That is the only time I've ever heard of a non-dilivar stud breaking.

-Andy

[p911sc]

Actually, none of the studs were replaced. All were retorqued. 2 of the bad studs are on the side of the engine that was not taken apart and 1 is one the side that received the work.

That is a good suggestion with the welding of the nuts. I don't have any welding equipment though. I was looking at 101 Projects for your 911 this evening and I noticed the section about how to loosen the loctite on the head studs, using a propane torch. How difficult is this? Is there any risk of overheating the case? and damaging the female threads in the case or breaking the studs??

[Eagledriver]

I bought a cheap 199 dollar wire fed welder from Autozone. I've used it several times now. It works fine for jobs that don't require good welding. It works like crap if you want a good weld. The wire feeds too fast even on the slowest setting. It was worth it just for removing the studs though. I had never welded before I bought it. If I had to do it again I'd buy a better MIG welder for around 4-5 hundred from a place like Eastwood.

You can heat the studs with propane but MAPP gas works much better. You don't have to worry about overheating the case unless you use Oxy/Acetaline. I tried it this way but it was much slower and more difficult than the welding on of the nut solution. You can also weld nuts on the broken studs if there is enough sticking out.

Don't reem out the stud holes with a tap, you'll make them too loose.

-Andy

[p911sc]

Thanks Andy! I will let you know how it goes.
Rick

[p911sc]

Thanks Andy! I will let you know how it goes.
Rick

[Jim Sims]

"Don't reem out the stud holes with a tap".

One uses a chasing or clean-out tap; it does not "ream" out the holes. It isn't a "cutting tap", there's a difference. Not cleaning out the threads in the case can make installing the new studs problematic.

[john walker's workshop]

find another mechanic. you can get a complete valve grind AND head studs around here for less than $4K. rip-off!