Broken Head Stud...Now What?

JLGarbanzo · 08-09-2006, 07:33 AM

So i finally get my CIS tuned and running beautifully (modified my WUR and purchased a lm-1) and decided i would finish my tune up with a valve job.

As you can expect, i cracked open the covers and saw the head stud from the back of the engine (cylinder 4 ) fall to the ground. Yes, my stomach also fell to the ground at this point. I was certainly in a less that stable mental state for the remainder of the day.

So now that i have slept on the situation and it's a bright sunny day outside, what do i do now? Since it is only one stud, can i have it drilled out and replaced or do i have to have the whole engine torn down and replaced with steel studs? I am a college student on a college budget, but i do want things done right in my pride and joy.

Also, if anyone has suggestion for a shop in CT that would do the work at a reasonable price, please let me know.

Zeke · 08-09-2006, 07:46 AM

Drive it with no worries. Don't race it too hard. Eventually, you'll find some other reason to pull the motor and then you can address the stud. As they say, "One monkey don't stop the show."

defcon65 · 08-09-2006, 07:58 AM

That's good advice, Zeke. Sometimes I think we get a little too worked up about something in our cars that is less than perfect when it probably won't affect anything short-term, day to day. Take a deep breath and make a mental note.

jabb · 08-09-2006, 08:06 AM

2 shops come to mind that you can use in CT.
If you are in the Greater Hartford Area check out Musante Motor Sports. In the Greater New Haven Area check out
Dan Jacobs LLC / Hairy Dog Garage. This fix will not be cheap.
With one Broken Stud you can drive the car for a while .

osidak · 08-09-2006, 08:10 AM

If it is just one I would say you are ok - Do the work yourself though - save a bundle and learn more than you ever cared to know about the inner workings of your car.

When I had 6 broken studs I was quoted prices that ranged $2000 to $11000. Pulled the engine and did the work myself. Took me a year as I was having to save the cash and pay as I went but in the end I saved a bundle and did some needed upgrades at the same time

sammyg2 · 08-09-2006, 08:21 AM

If it is just one, and it is IN THE MIDDLE OF THE BANK you have better odds of driving it without causing very erxpensive damage.
The reason is that the cam housing provides some stability and srength similar ot a strongback. If the broken stud is on the end you loose some of that extra strength and the odds of damaging a cylinder and head go up.

I had a broken stud in the middle (#5 cyl) and i drove it for over a year on boost with no damage at all. Others have reported damage that required replacing cylinders after only driving for a short distance.
When i finally decided to replace all the lower studs on mine it cost less than $1200 because I did it myself and the engine was in suprisingly good condition, I found nothing wrong or worn except for the broken stud. YMMV.
Also some of that cost was offset when I sold some of the special tools I had to buy after i was done with them.

Understand that you may be able to drive it for a long time without any adverse effects, but if you damage it and have to replace cylinders and machine heads it can really expensive really fast. Judgement call.

john walker's workshop · 08-09-2006, 08:46 AM

i just fixed an '83 that had one outer stud broken and it sounded like several were broken when you accelerated. surprised to find just one. best fix it now or damage will result from the head beating on the cylinder every time it fires. aluminum is soft you know.

JLGarbanzo · 08-09-2006, 08:50 AM

john,
What is your fix of choice? Do you drill out the one stud or tear down the whole motor?

JLGarbanzo · 08-09-2006, 08:54 AM

I read up on this for a while before posting and I would prefer to get the car fixed. The stud that broke is on the outside (back) of the engine, so I feel that the location is more critical than a central stud.

This car is my first 911. I bought it in fair shape for a great price to learn and work on without taking a huge monetary hit. The car is now MUCH cleaner than when I purchased it, but by no means showroom quality. I have taken my time and everything I have done, I have done the right way. With the work I have done to the car, I can still (hopefully) sell the car for a few grand more than I purchased it for. Therefore, if I can fix the stud for a reasonable price, without screwing the next owner, I would be ready to part with the car and move on to a cleaner specimen.

Any suggestions?

Grady Clay · 08-09-2006, 08:56 AM

JL,

“…with a valve job.”
I think you mean valve adjust.

I agree with John, it is best to do a “top end” and fix the problem now. Yes it can become a problem and damage the top of a cylinder and the mating surface of the head. If it isn’t leaking now, yes you can drive it.

Before I chime in and agree with everyone about driving, how about a little more info. Exactly which stud is it? Are there any signs of leakage (black or oil) between the head and cylinder? Next I would do cranking compression and cylinder leak tests.

As you drive, listen for any compression leak under high load. It is usually audible under high loads and lower RPM.

If it continues to be drivable, start your “wish list” of upgrades and mods. Start a savings account just for this. Eventually you are going to want to have the heads professionally done. You can do everything else. Perhaps a cam change, resurface the rocker arms, add SSIs, inspect the pistons & cylinders and more. I recommend you change the fan and fan housing from the 226 mm fan to the 245 mm fan. You already have the 134 mm crank pulley.

Don’t let this interfere with your studies. It is OK to preserve and park it until graduation.

Best,
Grady.

john walker's workshop · 08-09-2006, 09:03 AM

drilling is a last resort. they break in one of two places. between cylinder and head and below the cylinder, close to the case. the latter can pose a problem. how long is the broken piece? 5" or 2"?

azasadny · azasadny's Garage

I drove my '911 for several years (spring/summer/fall) after finding several loose head studs on cylinders 1,2 and 3. I retorqued them and things were better, although temporarily. I replaced the engine this summer and sold the old longblock to a fellow Pelican as a rebuidable core and bought a recentl;y rebuilt 2.7L engine from another Pelican. I had lost some compression, and the "pfut, pfut" sound was obvious, but I didn't have the time/money or inclination to replace the engine until this year. I probably pur 3-4000 miles on the engne when the head studs were loose...

sammyg2 · 08-09-2006, 11:30 AM

Two things here, his engine is an aluminum cased 3 liter and they tend to break studs, not pull threads like a magnesium cased 2.7

On a 3 liter engine with a broken stud, you need to pull the heads and cylinders off to replace the stud. If you are going to that much trouble, common sense tells us to replace all the lower studs at the same time. No sense doing all that work and then having to do it again in 2 months.

If you decide to get it done the engine will have to be pulled, the cam housings, heads and cylinders will have to be removed.

After that it is all up to the condition of the parts and any "while you're in there" projects or upgrades.

If the bottom end is in good condition you can avoid having to rebuild it but some whould say to do it anyway just because it makes sense. Condition will help you make that determination.

If your heads and valve guides are in very good shape you could clean them up and re-install them, but others will recommend to have then rebuilt. Again, condition will tell you what you need to do, budget will tell you what would be nice to do.

If you have nikasil cylinders the chances are they are not worn and can be cleaned up and re-installed. You should replace the rings at a minimum.
If you have alusil cylinders .... well i won't get into that argument but some people say you can re-ring them, some say you can't.

Bottom line is you should do the top end and replace all the lower studs with steel studs as soon as you can based on your circumstances.

If you can do the work yourself you will save a considerable amount of labor but this isn't a job for someone who isn't comfortable with rebuilding engines, especially since the flat six has a few "quirks".

If you are going to have someone do it for you figure between $3500 and $5500 (rough guess). Might be higher if there is damage, might be less if there isn't.

If you do it yourself you can do it cheaper depending on what needs to be done.

Fix the engine based on what it needs, not what you can afford.
The budget should only determine if you want to do it now or later, if you are going to do upgrades while you're in there, and if you want to do some overkill just because.

JLGarbanzo · 08-09-2006, 02:50 PM

Here is a picture of the broken stud. I also looked under the car and i can see that the leftover stud DOES makes it from the block into the cylinder heads.

The car has plenty of nice things about it: Koni shocks all around, upgraded sway bar, short shift kit, large front mounter oil cooler, SSI...

BUT it also had a ratty interior that needs to be stripped clean. There is one spot of rust bubble, isolated to the left front fender, but i assume that will need to be replaced someday. The paint is also a complete mess.

I cant decide if the car is worth dumping money into. I know that if i start with the engine, the rest of the car will have to be done over for me to be happy.

I guess what i am saying is that this is really the point of no return...I guess its my decision.

Suggestions?

john walker's workshop · 08-09-2006, 03:25 PM

it broke low, near the case, but it appears you have a reasonable amount protruding from the case, so you can get a grip on it in a few different ways. the short stud removal really should be done by someone who is experienced, or you can blow the one chance of an easy removal and end up having to drill, or EDM the remains. do all the lowers at the same time. plenty of info here in the archives. use an oxy/acetylene setup to heat the case. lesser flames take bloody forever to loosen the loctite. sometimes you get lucky and most or all of the studs come out without any heat, but don't count on it.

Grady Clay · 08-09-2006, 03:31 PM

From your description you probably didn’t pay much for the SC. You need to ask yourself “Will the car be worth significantly less with a head leak than it is now?” You also need to ask yourself “Will the many thousands $ necessary to do this right pay off in increased sale value?”

You also need to consider the “someday” paint and interior. What about the 915? Where there is a little rust showing there is always more unseen.

It might be best to drive it until the head leaks and then part company. The best value is to buy the absolute best condition 911 you can afford and still be prepared to fix things.

Best,
Grady

sammyg2 · 08-09-2006, 03:40 PM

JL, you really should listen to the last two posters that replied to your thread (JW and Grady) they are the best around.
You would have a very hard time finding anyone who knows more about these cars than those two guys.
I'm jealous because I've never had both of them reply to one of my threads.

JLGarbanzo · 08-09-2006, 03:42 PM

Thanks John, I might have some leads on places in CT that will let me observe/participate in the process.

Grady,
I did get the car cheap, cheap enough that i think i could put another 5k into the car is still walk out unscathed. If i do invest in the car, i probably wont be looking to turn it around. I guess my decision would be to dump it now, or go for it all and hold onto the car for a long time. I mean, with the motor pulled, i could strip the car and paint it now. Maybe even invest in a decent set of race seats… I already have my own design for a custom set of door panels modeled after the RS America panels. I guess it really depends on how much money if left in the coffers when i am done with the engine. I will try to do much of the work on my own, under close supervision.

JLGarbanzo · 08-09-2006, 03:45 PM

Grady,
i forgot to mention, i have reciepts for the 915 rebuild right before i purchased the car from the PO. I my opinion it is shifting pretty smooth.

Zeke · 08-09-2006, 04:13 PM

Quote:

Originally posted by JLGarbanzo
.....
This car is my first 911. I bought it in fair shape for a great price to learn and work on without taking a huge monetary hit. The car is now MUCH cleaner than when I purchased it, but by no means showroom quality. I have taken my time and everything I have done, I have done the right way. With the work I have done to the car, I can still (hopefully) sell the car for a few grand more than I purchased it for. Therefore, if I can fix the stud for a reasonable price, without screwing the next owner, I would be ready to part with the car and move on to a cleaner specimen.

Well, I wouldn't count on that too much (few grand more). But, you sound like an honorable kind of person. We don't seem to have too many of those in the world today. If you do some or most of the work yourself, you will certainly be ahead of the car, financially speaking. The reason I said drive it is because, yes, there are many honorable persons such as yourself on this bbs and doing business as Porsche mechanics. But, me thinks the majority of Porsche mech's are not on the board. It takes a lot of time to be here like JW and GC are to give their excellent advice.

My problem with a situation such as yours is that someone gets into the job and starts finding "things to do." It's also called "while you're in there." So, I guess if you're gonna do it, find the best, most honest and brace yourself for the worst. Hopefully that won't occur. You deserve the break, tell the world I said so.