Bob D

Started my love affair with Porsches nearly 25 yrs ago and have owned several 9ll's. I've been Porscheless for the last 3 yrs and was deeply involved in 356's for the 6-7 before that. I've recently decided to get another 911 and am probably leaning toward an SC. My question is this, I've not owned a 3.0 or 3.2 for over ten years but I don't remember there being a head stud problem with these engines back in those days. (I've owned three of these cars in the past). Can anyone shed some light on the history of this problem and what causes it. As I read thru the past posts it seems that people think this is as prevelent a problem as pulled studs in 2.7. I'd welcome any comments. Been away for awhile and just trying to get up to speed..no pun intended.

Bob D.

JBO

It is a definite problem, and they continue to break as time passes. Idealy the SC or carrerra, but particularly if its an SC, will have had the lower studs replaced. You can check for broken ones at the PPI, but if they are not broken but still the originals, they could break the next day or years later. It's a time bomb. It is the single biggest problem with an SC, and it is a problem with Carrerras, but they also have valve guide issues.

imcarthur

From what I've read heat, humidity & lack of use are catalysts for the problem. Porsche started epoxy coating them around 83 & that reduces or delays (the jury's still out) the problem.

A PPI with a valve cover drop - an extra $100 - $200 p&l - should be mandatory for an SC & a good thing for a Carrera.

Ian

imcarthur

See Pelican Thread on the same topic.

Ian

Peter Zimmermann

Hi Bob: Be careful regarding low mileage SC head stud issues. Those cars bring the big bucks, and are most likely to have stud issues. Always have a PPI done on potential cars to buy, and always have the valve covers removed to make sure all the head nuts are still there. The design of the stud changed sometime in the '84 model year run (I've never spoken to anyone who knows for sure), and those studs were coated with a black material almost like thick paint. That has slowed corrosion issues to the point where broken studs on 3.2 Carreras are rare. However, I own two SCs, and drive both regularly. My '80's engine is totally original, just turned 188K miles, no broken studs. My '82, also totally original with the exception of new cams installed two years ago, has 202K miles, no broken studs. I'm of the opinion that the key to longer stud life might be related to if the cars are driven to full temp following most starts, and driven conservatively when they're cold. The first "Dilavar" studs appeared in late '77 2.7 liter engines, lower only w/steel uppers. They had a silver finish, almost a brushed look. Sometime in '80 those silver studs became gold, and were used, as far as I've been able to learn, until '84, also on the bottom only. All Turbos of that generation were fitted with 24 Dilavar studs instead of the 12 in the normally aspirated cars. Replacement studs today are also coated black, but they are threaded the full length of the stud. When repairing an older engine with the new threaded studs it's recommended to replace all 24. I guess 10 or 12 more years and we'll know how good they are! No one knows for sure why they break, but the broken ones that I've dealt with, in SoCal's moderate climate, have all had heavy corrosion a couple of inches from where the head nut fits, and the studs broke at the corroded area. Hope this sheds some light on the stud issue, I guess that it's a crap shoot.
Pete

Bob D

Pet, et all,
Thanks for the info. It's all starting to make a little more sense now.The Pelican thread was extremely helpful. I can only assume that the studs were not a problem on my previous cars because they were all relatively new, Colorado cars (high and dry, no corrosion), driven often, but seldom in bad weather and never really abused. In those "days of old" I did all my own work, including engine and gearbox builds and plan to do the same again. I can see this forum will be a great resource.
Thanks again

Bob D.