PPI gone bad! Always remove valve covers!

pryord · pryord's Garage

After searching for three months, I thought I had finally found a solid SC. I found an '80 with 85k miles. It had paperwork for all repairs/maintenance, updated tensioners, pop-off valve, new tires, recovered dash etc. Because of this website, I knew I should be wary of broken head studs, so I forked out the money for a PPI. I went to a shop recommended by several Porsche buddies and told the guy at the desk that I was particulary concerned about the head studs.

The car came out of the PPI with glowing results. 180 - 185 accross all cylinders, no wreck damage, etc. So I bought it for $9,700. In reviewing the records from the previous owner, I couldn't determine when the last valve adjustment was done, so I had one done yesterday. Guess what?! Yup, one broken head stud on cylinder #5!

I'm pretty upset! I realize this is not an uncommon problem with SC's, but I thought I had done everything to avoid having to pay for new head studs right away. My advice to future SC purchasers: have your PPI mechanic remove valve covers to check for broken head studs, no matter what they say. It turns out my mechanic depended on compression test results to evaluate the head studs.

So I've been told I can drive the car until I hear the exhaust start to pop or even worse, the cylinders begin making noise. Is this true? Can someone recommend a mechanic in the Pacific NW for this sort of work? Should I go ahead and do a top end rebuild while the engine is in pieces?

Thanks for letting me vent,
David

Jdub · 03-14-2002, 06:33 AM

I guess the lesson here is to make sure the tech. pulls the valve covers as you have said. However, make sure that the tech. also puts a hex to the nuts as well, but be so very careful to tell the guy not to retorque, but rather give the hex enough of a twist (by hand) that you know the stud is not on its last legs.

Very sorry to hear this happened to you. I guess I would have words with the folks who did the PPI. Maybe this would reset their thought process on what constitues a check on head studs. They are in the "Whoops!" category of Porsche PPI'ers: they have your money and will give you back their sympathy.

For mechanics, I understand there are many good ones in Portland (a wonderful city to boot!). If you wander up North, in Seattle there are at least two shops I'd recommend.

I would be very careful driving the car with a broken stud. Folks I trust disagree on this point, so I am only passing on my personal thoughts and leave it to the experts to judge. It's the ramifications of a bouncing cylinder head that you have to watch with your weather eye.

Good luck,
John

jason1guy · 03-14-2002, 06:56 AM

i have an 81 and my story reads just like yours. 1 broken stud, no other problems. i had my car in the shop for a clutch and while they were at it they tore the engine enough to replace the stud for 700 in labor. some would say this is not the way to go, and in fact is a gamble. its been 1 year with no problems. just a thought

Jason
81 SC

88911coupe · 03-14-2002, 06:59 AM

Isn't John Walker in the Pacific NW?

Groesbeck Hurricane · 03-14-2002, 09:12 AM

If you are not going to do it yourself, get in touch with John Walker!!!

pryord · pryord's Garage

I already got a hold of John. He seems like a great guy.

David

Wayne 962 · Wayne 962's Garage

There are many SCs out there with broken studs, and the owners don't even know it. You can drive the car fine with one broken stud. Just keep listening to hear if the other one breaks too.

The heads are not going to flap around, as they are held on with the cam towers, which also increases stiffness in that area. If you hear an exhaust popping noise (exhaust leak) then it's time to rebuild.

You should be able to get your PPI funds back from the mechanic (I have done this before - long story). Don't expect much more though. They can claim that the stud broke on the way home from the shop...

In general, I would drive the car and not worry about it too much...

-Wayne

mwbaum · mwbaum's Garage

Ditto for John.....gives you an excuse to roadtrip overnite to Seattle and check out the town while he fixes your car!

rickeolis · 03-14-2002, 01:09 PM

Everything I have heard and read for years tell me that the head stud issues were only for the 1975 to 1977 models. If this is an issue for the '80 model, what other models should I be concerned of, and why do I hear only these models for the problem?

Adam · Adam's Garage

When you say exhaust "popping", do you guys mean like a manifold gasket leak, or popping on the overrun/decelleration with engine braking? What about popping on the rev-drop while revving it at standstill?

My car is overdue for a valve adjustment and has been through various head-stud dramas (very expensive!) so I'm naturally concerned as mine makes these popping sounds.

pryord · pryord's Garage

Thanks for your advice Wayne. I figure I might as well drive the car a while and do a top end rebuild in the future while I'm having the studs replaced. If I stop driving the car when I hear the symptoms you describe, I'm not adding any extra problems for the rebuild am I?

Superman · 03-14-2002, 02:01 PM

Okay, time to tell my story again. I bought a nice SC with 135K miles but without a PPI. Turns out it had a broken head stud. I drove it to 183K miles and refreshed the engine, including new studs, valves, bearings, etc. It was making a clapping sound, according to my autocross friends, and I can tell you it was also backfiring on closed-throttle deceleration.

What I found is that the broken head stud caused no additional damage. At least three of my heads were beat up from banging against the cylinder, but my engine had only one broken stud. The moral of this story is to retorque head stud nuts periodically, particularly during the breakin procedure. I am just now bolting the engine back together.

So, drive it as much as you like and repair it when you want. With only 85K miles, I'd say you could take each bank of heads off, replace the studs and bolt it all back together at a cost of $300 in parts, plus labor. Having a top end job done at the same time increases the expense, of course.

I'd agree that John Walker is the "go to" guy in our area. There is at least one other respected name in Seattle, but I know from personal experience that John is a guy I'd take my car to. I trust almost no one with my car. John is especially awesome if you're going to do the work yourself. I just hope I have not made him start to detest DIY guys. If he had charged me by the question, my bill would be enormous.

I don't know when they quit using those Dilivar studs, but they were sure using them in July 1983 and I think at least several years beyond. The SC folks are changing out all those Dilivar studs now. It's all part of the SCWDP. Those poor Carrera guys......

emcon5 · emcon5's Garage

Quote:

Originally posted by rickeolis
Everything I have heard and read for years tell me that the head stud issues were only for the 1975 to 1977 models.

Different issue. 2.7L cars have a bad reputation for pulling head studs, as in the stud pulling out of the magnesium case. 3.0 and later cars are starting to experience broken head studs, due to either corrosion or just age, depending on who you ask. Probably a combination of the two.

My bet is that 3.2's will start showing them soon, as they have Dilivar studs on the bottom rows. Thom (widebody911) even had a 3.6 with broken head studs, so it may be a problem with them as well.

Tom

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by emcon5

Different issue. 2.7L cars have a bad reputation for pulling head studs, as in the stud pulling out of the magnesium case. 3.0 and later cars are starting to experience broken head studs, due to either corrosion or just age, depending on who you ask. Probably a combination of the two.

My bet is that 3.2's will start showing them soon, as they have Dilivar studs on the bottom rows. Thom (widebody911) even had a 3.6 with broken head studs, so it may be a problem with them as well.

Tom

Yep, the 3.2's have this problem also. Fixed an '86 with one broken head stud this winter.
-Chris

Superman · 03-14-2002, 04:12 PM

Two more things. I would not feel comfortable with Dilivar studs if they were coated with kryptonite, epoxy or anything else. I have eleven used Dilivar studs for sale, cheap!

Also, my cylinders measure no more than .04mm out anywhere. That's no more than .04mm bigger than stock diameter at any location on any cylinder. That's about .0015". When I asked one of my most experienced mechanic friends whether he'd agree that was a small amount of wear, he said he wouldn't call it small. He said he'd call in MINISCULE. He said he's successfully re-ringed (non-Porsche) engines with .020" taper. So apparently, these fancy German cylinders are pretty different from others. Again, this engine has 183,000 miles. So, feel good about your Porsche engines.

pwd72s · 03-14-2002, 04:22 PM

Superman? I'm assuming you went with the raceware studs?

78targa · 78targa's Garage

Well, Just to add to the information pool, the following is an excerpt from the Pelican Parts Catalog. Courtesy of Wayne:

As the displacement of the 911 engine increased over the years, the increased stress caused by differing thermal rates of expansion often caused the head studs to break or separate from their mount in the case. This often resulted in a leak between the piston and the head. Porsche decided to solve the problem by using Dilavar studs. However, there were reports of these studs breaking under pressure prematurely. There are a few good solutions. You can replace your studs with the standard Dilavar studs that the factory began using in 1984. Or you can use high-strength Raceware studs. Made from high tensile strength steel, and combined with time-serts placed within the case, you should no longer have any problem with head studs pulling out. Another alternative is the factory replacement for the Dilavar studs, which are micro-encapsulated steel studs. These are coated to prevent the surface corrosion that is believed to contribute to the premature failure of the Dilavar studs.

gslater · 03-14-2002, 04:54 PM

Mr. John Walker certainly seems like an excellent guy, and I appreciate all that he contributes to the board, but if you're looking for someone in Portland, there are several good choices. My personal favorite is Michael Jordan at Stuttgart Autotech in Lake Oswego (503-635-3098). I've raved about him plenty in the past, so I won't do it too much here, but he's EXACTLY the kind of person I want working on my SC...

Doug E · 03-14-2002, 05:23 PM

$9,700 ??? That sure seems like a good deal to me for an '80 with 80k. Was there any rust or body damage anywhere?

83SC in PA · 03-14-2002, 06:31 PM

Wayne sez:

"there are many SCs out there with broken studs, and the owners don't even know it. You can drive the car fine with one broken stud. Just keep listening to hear if the other one breaks too."

There's a guy on the Rennlist board who has discovered that he has a single broken head stud and he asked whether or not he could continue to drive his car. Most everybody suggested that he should have varying degrees of work($$$) performed on his engine before driving it again. When I suggested that in my opinion he could go ahead and drive his car with just a single broken stud, the suggestion was met with derision by one poster who suggested my 'advice' was 'very bad'. Most of the other posters agreed with him. I suggested that he check the myriad of 'head stud' threads on this board, but the tone of the thread makes me think this guy is going to either mothball his car until he can afford the work or go out and spend a lot of money unnecessarily. A shame.