Headstud Removal - Central Texas

Groesbeck Hurricane · 12-27-2001, 09:40 AM

Motor is torn apart and I am unable to remove 5 of the headstuds. Has anybody in Texas taken their 3.0 to have the studs drilled out or otherwise removed? I am 2 to 3 hours from DFW, Houston, and Austin and fairly close to Waco. Any input is greatly appreciated. Please let me know your experience, good and bad.

on and engine with just over 100K, the pistons are good (new rings and a cleaning) and the cylinders are smooth. Need new exhaust valves (sodium) and valve springs, guides, etc. Doing timing chain and tensioners, gears, rails. New gaskets and bolts/nuts.

Anyone have a good test to ensure the catalytic converter is still good?

Am I missing anything else? The cams are in great shape and I plan on re-grinding the intake valves. PO had the clutch and pop-off valve done in Houston. I just want a daily driver we can take trips in and enjoy. Close to bullet proof as possible.

Doug Zielke · 12-27-2001, 09:45 AM

David,
See the section on EDM (Electron Discharge Machining) in Wayne's 101 Projects.

RoninLB · 12-27-2001, 10:44 AM

I sent my heads to Competition Engineering in Calf. for head work. 911 heads are to delicate for routine/typical shop work. CE is good enough for the big guys in PANO, so they are good enough for me. If you have cast pistons they are probably beat. Make sure top ring land is WELL with in specs. CE is 760-379-3879. Raceware or ARP head studs and rod bolts are important IMHO. I can't imagine torqueing stock rod bolts.

5axis · 11:34 AM

If they are broken off in such a way that you can not turn them out, then you will have to try and drill or EDM. If you have to EDM try these guys. Be nice and explain your problem, since it falls far from precision work they might be nice and sneak you in cheap and fast as a unofficial job. If they are unable they will likely be able to point you to a shop that can help. Many shops are very slow due to the current economy so they may be willing to help you out. Who knows maybe the owner likes Porsches

http://www.applegateedm.com/

12919 Valley Branch Lane
Dallas, TX 75234
Phone: (972) 488-8997
Fax: (972) 488-3316
Contacts:
Terry Click, Manager
Rich Juhnke, Manager
Wayne Applegate, President

good luck
david 89 turbo cab

john walker's workshop · 12-27-2001, 01:31 PM

if the studs are not broken, use an oxy/acet torch to heat the case inside the cylinder bore, adjacent to the threads, if there still is a bit of stud protruding from the case, weld a nut on it with a wirefeed or heliarc welder, and heat the case too. the vaporizing method screws up the threads, so a timesert is necessary, so if the stud is flush with the case, why not set it up in a mill and bore out the stud/hole to the size needed to tap for a timesert.

stormcrow · stormcrow's Garage

I had a few broken studs with about 3" remaining. I took a 8" pipe wrench and it did the job. If the studs are really stubborn, spray with liquid wrench or similar, wait overnight and then try to remove them

Turn in one direction and then in the other direction. This helps loosen the threads and lets the liquid wrench seep in.

Steve

5axis · 12-27-2001, 05:29 PM

John your EDM guy must suck. There is no reason for the threads to be damaged unless he was unable to locate the center of the hole. We often have to remove broken drills and taps from expensive tool and mold components and unless the guy blows a calculation everything should be as good as used.

David. If timecerts are fine, then it would take very little to cnc mill the broken stud and make the timecert hole. The actual machining should only take a few minutes, the setup, finding the center location and writing the program should take just a bit longer. You should be able to find a shop close by. Most of us machinist types are gearheads of one sort or another, so they will likely be understanding and enjoy checking out Porsche stuff.

speeder · speeder's Garage

I have a question about heating case to remove stud; how hot? Red hot? Any risk of damage doing this? I'll be doing this job soon.

Groesbeck, I would definitely investigate pipewrench/stud-removal tool method before going drill/machining route. You can buy the correct size stud-removal tool off any tool-truck. They usually come out, from all I've heard and read.

Also, FWIW, I've researched the dependability and lifespan of different components on these engines. I strongly disagree that your pistons would be "beat" at 100k miles. This runs contrary to every rebuild report I've ever read, and that's many. Rings definitely since you have it apart, but other than head-stud problem, SC motors typically go 2 or 3 times this long w/o any internal work w/ good maintenence. Chain rails also should be replaced, go w/ carrera tens. if not already there, but chains should be no more worn-out than cig-lighter, if a non-smoker. Current knowledge says use steel factory studs,(ones like top row), Raceware are great but over-kill on bone-stock motor. Same w/ rod bolts, I've never heard of them failing on SC,(3.2 is different story), but must be replaced if removed- not re-usable. Ditto on valve springs- have them measured, shim w/ factory shims as necessary like they did the first time. They are not usually replaced on the job you are doing. To do top-end/stud-repair on street car that you will take trips with, factory parts are plenty good. My .02 gathered from the .02 of top experts. Good luck.

RoninLB · 12-27-2001, 09:39 PM

My wording of "beat" refers to top ring land. Replacing old rings w/new rings in a ring land that is at max spec. is a problem waiting to happen. The new ring will get a better bite on the cyl. than old ring. The new ring will bang around more in the enlarged groove. The increased banging will further increase the size of the groove and the new ring may prematurely break. IMHO, the top ring groove must be within spec. A rebuild should last 100,000 miles, not 40,000 mi, maybe not 20,000 mi. On Raceware studs, exhaust side is very imp. Intake side does not seem to snap as often as exhaust side. On stock rod bolts. Over rev stock bolts and see what happens in 10,000 mi. May be nothing, may be blown eng. On torqueing stock rod bolts, to get accurate numbers the procedure must be done on the final pass perfectly. On Raceware or ARP rod bolts if not done perfectly on last pass they could be loosened to over come friction of nut on retightening. Measuring stretch of stock rod bolts will be exciteing, IMHO.

speeder · speeder's Garage

I would certainly concur on measuring ring land to ensure that it is not worn excessively. I had just not heard that they would be expected to be shot at 100k miles. I also thought that pistons were forged aluminum- this is not so? I am definitely not the final word on rebuilding, but I have been trying to acquire as much knowledge/info as possible on it and reading reports such as the one in recent 911& Porsche World "project SC" article. They rebuilt w/ almost 200k miles and said that p/c's were fine to reuse- minimal wear. Also have read and heard that valve springs and cam chains are totally reusable even on thorough and professional job. If in doubt, chains and sprockets are easy enough to measure/ inspect. I certainly welcome any further info from informed sources, however.

stormcrow · stormcrow's Garage

When I did the rebuild on my 78 911 SC Targa, an inspection on the internals reveled everything was ok. When you are doing the rebuild, check and make sure everything is done according to specs. If you do this, you won't have any problems.

As far as pistons, check the grove tolerances as well as the jugs. Mine were in excellent condition, nothing was out of spec or worn.

As far as the crank bolts go, I ordered standard bolts and installed them - havn't had any problems yet.

The key to keeping your 3.0 from coming apart is making sure the rebuild is done to specs. If you do this, your engine will be good for another 150,000 - as long as you don't abuse it.

Steve

Groesbeck Hurricane · 01-02-2002, 06:34 AM

I am a little confused. I put a micrometer to the sleaves and note they are all on the low end of the dimensional tolerance. I have not weighed the cylinders as they clean up nicely and have no appearance of wear. The cam shafts are clean. It appears my main issue was the broken studs and timing chain tensioners. My father in law (a former mechanic) nor I do not see any adverse signs of wear or anything out of tolerance. Could it be the Porsche Gods have smiled in my little car?

Now to the issues of removing the broken and twisting studs. I am continuing soaking penetrating oil and praying. Wayne's book should be here soon.

Should there be a Central Texas Shop on putting the motor back together? It would be about eight weeks away if I did. Any interest?

When my provider gets back up (Sprint lines have been acting up most of the last several weeks) I will make a posting of my teardown pictures and post the site address here.

john walker's workshop · 01-02-2002, 08:13 AM

penetrating oil will not work. the studs have loctite on the threads and the oil won't get past it. heating the case bore with an oxy/acet torch is the only way to release the loctite's grip. ( heat in the cylinder bore, right along where the threads go). if you don't have a stud removal tool, use vise grips on the stud. keep tension on it while you heat the case, and soon you will feel it start to turn. heat it just enough to keep the stud turning. do not heat the stud because it will twist.

speeder · speeder's Garage

David, If you are saying that ring grooves are on low-end of spec, that is where we like them of course. Also, Porsche gods have smiled on all of our cars, check Roland K.'s post on "996 durability" thread.

Superman · 01-02-2002, 08:18 PM

Measure everything. If you don't have a Spec Book for your car, get one quickly. I can provide specs from mine which covers '83, '82 and I believe perhaps '81 (not sure). there are specs on things like cylinder bore and ovality, and tons of other measurements. That's what these guys, Like Steve, are trying to say. Get the specs and measure all those engine parts.

As far as the studs go, it is my understanding that heat is what works. No, the case would not be cherry red. It is aluminum and it is certainly possible to get it too hot. So just be careful. Heat the case evenly around the stud, without heating the stud more than necessary. JW says you'll feel it come loose.

rcwaldo · 01-02-2002, 08:49 PM

If you are worried about overheating the case, you can buy a heat stick that melts at a pre-determined temperature. I use a 250f heatstick. I wouldn't heat aluminum any more than that.

I agree with John. The studs are loc-tighted in. Heat is your friend

Chris

Groesbeck Hurricane · 01-03-2002, 05:51 AM

Thanks yall. I will attempt to borrow a welder to heat up around the studs. This will leave me with three that are broken off near the surface. I will attempt to weld, heat, and turn in the near future. Wayne's book should be here today and I will read up on EDM and talk to the guy down the street who is a machinist to see if he has CNC equipment.

Also, just to lay my mind at rest, It was my impression that timecerts were necessary only where the studs were drilled out. I will go back with either OEM steel studs or raceware. I have not found my safety zone yet on OEM studs.

Superman, I have the factory manuals and will work this weekend to measure all aspects of the pistons and clynders. The inner dimensions on the cylinders are fabulous, cylinders appear like new without cleaning, and the cams appear like new with zero scoring or scratches. We can our fingernails (real exact test) up and down the cylinders and not detect any grooves. This is nothing like I have seen coming out of an overhauled engine before. I believe that I see a little better about measuring everything even if one part is well within spec. I'm very optimistic as all parts appear to have very little wear. I know new rings are definately in order and also plan to give new springs, guides, exhaust valves to the car.

john walker's workshop · 01-03-2002, 08:39 AM

on the three studs broken near the case, do a slight cleanup on the black broken end, down to clean metal, slip a quality steel nut over the stub, and have a shop heli-arc it to the stud. then heat the case like before and with a little luck the weld will hold and the stud will come out.

Superman · 01-03-2002, 02:08 PM

David, I understand wanting to make sure proper parts are used, but I am not sure stuff like springs need replacing. There are testing fixtures to ensure they have the same strength as new. Just have them tested. If they're fine, I'd consider them more reliable than new.

FWIW, John Walker trusts OEM steel studs and that's good enough for me. I am not tempted by raceware at all.

I am very encouraged by your description of the condition of your cylinders and I am wondering how loose your valves are. Is it quite obvious that valve guides need replacing?

Early_S_Man · 01-03-2002, 02:49 PM

You have to heat the block area around the stud to 325°-350° F to melt the red Loctite ... and that is nowhere near the melting point for aluminum! It would help if you had an assistant applying reverse torque to the stud while you are heating and moving the torch around continuously. When the stud finally moves ... that is enough heat, and the stud should come right out in less than a minute!