Broken Head Stud, Need Advice

[Jadams1]

I just finished doing the chain tensioners and was going to adjust the valves before putting everything back together. I pulled the lower right valve cover off and found a broken head stud. It’s the lower right stud on cylinder #6. Should I drop the engine and replace the broken stud? The engine has 107,000 miles and runs strong. I really don’t want to do a rebuild at this time. Any advice?

Thanks!

John

[rstoll]

I don't think one broken stud is anything to be concerned about. I would wait until you get ready for a top end job and replace 'em all.

[john walker's workshop]

ya pays yer money and ya takes yer chances. you stand a chance of having the head gasket ring blow out and chew up the cylinder top and head. regina beck could e/mail you a pic of hers. even if that doesn't happen, the head will beat on the cylinder somewhat every time the cylinder fires, because it obviously is not completely bolted tight. how lucky do you feel?

[Jadams1]

Not lucky, it's more like a sick feeling. I'm capable of doing the work so I just need advice and have to buy parts. Ive done a top end rebuild on a 72 911 so I know what I'm up against. JW, I found your pic of where to heat with torches. Is there a danger of overheating? I would feel better with all new steel studs I'm just bumbed I have to do it. I was just getting ready to put the car back on the road.


By the way, I found another broken head stud on #2. Here's a pic.

John

[jabb]

Some guys will drive with one broken stud on each cylinder...
If you do not do daily driving with the car I would drive it for the summer and do it over the winter... keep an eye and an ear on things if you start to hear loud rapping on hard acceleration
then the problem is getting worst.... dod a search on Head studs
and you will find more information then you ever wanted to know including the information about people that have driven with one broken stud on a cylinder.... The choice is yours.....

[john walker's workshop]

it's not too bad of a job, so you might as well get on with it, especially if you had engine experience. at least the studs broke at the head end and not at the case. much easier to get them out. you just have to heat the case for a minute or two, and keep tension on the stud puller at the same time. when you feel the stud start to turn, give it a couple rotations before shutting the heat off, so it doesn't bind again on it's way out. forget the propane and the mapp gas torches, and rent an oxy/acetylene setup that works.

[SteveT]

John,
I was in the same boat you are...........I am in the middle of putting my engine back together for the head stud thing.....turns out #4 both exhaust were broken. The car leaked alot of oil......but ran fine. In fact my mechanic told me we should take care of it within the next 30k........he knows his stuff.
But I am with JW on this issue, it just doesn't seem right to drive it like that. And because every time I started the car I thought about it after I found out..........But I drove it all summer without knowing they were broken.
I remember in my readings on this board, someone drove 50K before they took care of it.
I completely empathize with you, my car had 80,000 on it - great compression.........Damn Porsche Co. and those Dilavars......definitely replace all.
The upside is the studs come out fairly easy(the easiest part of the whole job for me) with an oxy/acet setup. I think you'd have to try to overheat the case to damage it. Just heat it where JW's picture shows - it'll be fine.
Good Luck, Steve

[Superman]

JW was my coach. No, you're not going to overheat it in less than two minutes, even with oxy-acetylene. In about half that time the stud will come loose.

I fantacized about the quick in-and-out micro-fix involving a grand total of 12 studs and a gasket set. But in the end I succumbed to the "while I'm in there" sirens' song. New valves, rings, bearings, blah blah blah. Perhaps you can do it. Courage man, courage.

Heck, if a guy were willing to reuse gaskets, the job could be done for about $12. But I guess that would be silly.

[Porcupine]

I thought 911 head studs did't break?

[Jack Olsen]

Porc, the steel factory studs have the reputation for not breaking. The Dilavar (factory) studs do.

[Wayne 962]

Ahh Porcupine, welcome to the club!

Page 43 of my book also shows where to heat the case, although the angle of the pic looks like it's heating the studs.

John, in general, I disagree with you on two counts here. The first one is that renting an torch to someone who might not know what they're doing could be very dangerous. Propane torches are very safe, even if they take forever to use.

Secondly, there are probably tons of 911 owners out there driving around with broken head studs who don't even know it. I haven't seen an engine that was damaged and wasn't making exhaust leak noises. In other words, if you can't hear it, then you should be ok.

Yes, in a perfect world we wouldn't have these problems. Here is what I am recommending in Chapter One of the new book:

Okay, so you’ve read about the head studs. You’ve checked yours on your car, and you’ve found that you’re one of the many 911SC owners out there driving around with a broken lower head stud. Many 911 owners have a panic attack when they see this, and many Porsche mechanics will instantly recommend a full top-end rebuild to repair the stud. However, I assert that the 3.0L and 3.2L engines can run perfectly fine with one broken head stud on each cylinder head. Each cylinder head has four studs that attach it to the cylinders. In addition, the heads are bolted to the cam towers, increasing their stiffness. If one stud is broken, the other three should be strong enough to hold the assembly together.

If two studs break on the same head, then it’s definitely time for a rebuild. In addition, if you can hear an exhaust popping noise when accelerating, it’s time to rebuild. Driving the car with an exhaust leak can cause the head and piston to vibrate and knock against each other. If this problem is left unresolved, then the exhaust leak can end up damaging the head and the piston. In general, if you have an exhaust leak at the junction between the piston and the cylinder, it’s best not to drive the car.

-Wayne

[82SC]

i don't know much about torches...but when I was doing my heat exchanger backdate...my home depot propane was not getting the studs cherry red like everyone recommended...

so I trudged down to home depot again

and low and behold they had a 2 tank torch, one tank was blue, the other was yellow...one was o2 I think...don't know if it was acetylene or what...but it is a very small setup...2 tanks with a common tip on the end of the hose...really easy to use...and heated them up to a bright cherry red...did take a little time though....not like the professional setup I saw at the muffler shops...

Maybe that will help you heat the studs and be safe as well...

[jabb]

A propane torch will not heat up the case to remove the stud...
it is not hot enough... I tried with a Propane Map gas torch and after 10 min I could still touch the case with my fingers the
Alum.... case is a large heat sink that just sucks up and disapates the heat.... You have to be careful with the oxy/acetylene but it is the only way to get the case hot enough to melt the loctite.....

[Jadams1]

I'm going to drop the engine and tear it down and replace all the bottom studs with steel ones. Do I order the studs that are used for the top? Do I buy the studs from Pelican or Porsche?

I do not want to risk additional damage which will cost more down the road.

John