Another victim to a broken head stud

[tazzieman]

Did come across a post on Pelican where he claimed he had 10 broken studs in his SC but the car still ran fine.

Yes but he used JB weld

[ANF]

My understanding is that Porsche designed these cars for 20 years/200,000km so I guess they are all on borrowed time now.  

Really? Is that all, seems like an alarmingly small number to me! 

[tazzieman]

Really? Is that all, seems like an alarmingly small number to me! 

The air cooled cars had some serious and unfortunate engineering problems, For 6 cylinder engine , that number does seem a little disappointing. If it were miles , OK but km?
Plus the cars cry out to be redlined often, whihc is a bit stressful and wearing! 

[Peter M]

Really? Is that all, seems like an alarmingly small number to me! 

 

Yes, that was the design perimeters set for the impact bumper cabriolets that they had to meet before they would be released to market.  They then had a series of accelerated testing to replicate that usage short term.  If you are particularly interested I can quote the source.

Remember at the time there was no expectation that these cars would have any long term value to anyone.

Yes but he used JB weld

Marinated in JB?  A variation of grouting the water jackets of drag cars to increase block strength and stability!

[tazzieman]

Remember at the time there was no expectation that these cars would have any long term value to anyone.

In the 70s there was a nod to longevity with the body galvanising 7 year warranty. (compared to "metal protection" on offer from other mfrs, light years ahead). But then as now , no financial point in building cars that are too reliable or durable (as Volvo found out). It's likely "future modern classics" will be rendered obsolete due to complexity/parts availability. We'll see.

[KGB]

In the 70s there was a nod to longevity with the body galvanising 7 year warranty. (compared to "metal protection" on offer from other mfrs, light years ahead). But then as now , no financial point in building cars that are too reliable or durable (as Volvo found out). It's likely "future modern classics" will be rendered obsolete due to complexity/parts availability. We'll see.

So, Volvo didn't go bust because they were building crap outdated cars with GM Europe one generation old underpinnings...they were simply a victim of being too reliable!

[ANF]

 

So, Volvo didn't go bust because they were building crap outdated cars with GM Europe one generation old underpinnings...they were simply a victim of being too reliable!

Do you mean Saab?

[ANF]

Yes, that was the design perimeters set for the impact bumper cabriolets that they had to meet before they would be released to market.  They then had a series of accelerated testing to replicate that usage short term.  If you are particularly interested I can quote the source.

Remember at the time there was no expectation that these cars would have any long term value to anyone.

That may be true and I am not doubting you, just find it odd as these were not cheap cars new and designed around the same time as the 928, differing philosophies from the same manufacturer....

[Peter M]

I think it may have been that the 911 represented the past and that model was expected to come to an end as front engined cars took over.   Like they weren't in any hurry to upgrade the cam chain tensioners in the SC's so I guess head stud revisions weren't a busting priority either.

[ANF]

I think it may have been that the 911 represented the past and that model was expected to come to an end as front engined cars took over.   Like they weren't in any hurry to upgrade the cam chain tensioners in the SC's so I guess head stud revisions weren't a busting priority either.

Even the smart ones get it wrong sometimes....

[Zelrik911]

So, Volvo didn't go bust because they were building crap outdated cars with GM Europe one generation old underpinnings...they were simply a victim of being too reliable!

I think you mean SAAB (Volvo partnered with Ford). And yes both were "too reliable" in their Swedish form.

Both were good cars & had enthusiastic followers (especially turbo geeks) until the Americans diluted the brands. SAAB became a rebadged GM car - like Holden in Australia, I think the last SAAB was a rebadged Subaru ??? SAAB wasnt unsuccessful per-se it was closed up for similar reasons for the Holden shutdown.

Was it pig-headed engineers or bean-counter accountants that continued with the Dilavar development when they should have rethought the issue? I bet these were the same guys that OKed the IMS 'solution' in the Boxster & 996.

Actually GM/SAAB had their own IMS-like stuffup when they under engineered the timing belt bearings on their V6 . They too used skateboard wheel bearings in that application.  Repairing a SAAB V6 after a timing belt explosion was so hard, it made working on an A/C flat 6 motor seem as easy as fixing a Victa motor mower donk.

Just think what will happen when a US manufacturer buys Porsche. P cars will end up like SAAB.

 

[bear924]

I wouldn't expect anything different to be honest. The bolts are not designed to be smacked with a hammer. The bolts are designed to be strong in axial tension.  similar things will happen if you hit window with a hammer

 

I understand your point however disagree. I've just replaced my head studs on the 924, I could hit them with a hammer and I'm confident they wouldn't break. I also suspect a new set of studs wouldn't break by a hammer hit. These studs fail because they corrode, the symptom of the corrosion is that they become very brittle, thus easily destroyed via a hammer.

[AndrewW]

So if you budget in some engine work in any SC you buy should that not also apply to the selling price of a recently sorted motor, well it should but nup.

I just bought an SC, after reading the above posts I feel that I've just taken up gambling.

Ahhhh, it'll never happen to me, good ole Aussie attitude.?

[KGB]

 

Do you mean Saab?

No, sorry, I meant Ford underpinnings.

[tazzieman]

I bought an old 911 because by and large it was made of high quality material including the bodyshell. Luckily I bought one that had suffered a bearing failure well before the 80,000km on the odometer , followed by a complete rebuild. Unfortunately the chain tensioner wasn't upgraded , so I had to fix the clatter. But now of course it's bulletproof and mechanically quite simple.

I could have bought an old HR Holden and enjoyed the same or greater capital increase. But it's not about investment is it?

[Peter M]

I just bought an SC, after reading the above posts I feel that I've just taken up gambling.

Andrew,

That's why I reacted to half baked assertions as I know it often causes needless anxiety.  Just drive it and don't give it a second thought.  

[AndrewW]

Drive it, apparently like you stole it !

[Peter M]

That may be true and I am not doubting you....

I would doubt me Adam as I got it slightly wrong!

Hans-Peter Bauerle, Weissach Test Engineer actually says in Leffingwell's Porsche 911 - 50 year book that "the bottom line to get the car freed for manufacture was that it must run 8,000km around the clock with no problem [on their test track].  Which is the equivalent of 180,000km on normal road..."

 

[tazzieman]

Anyone with butterflies after buying an SC should be grateful they didn't buy a 928 eh Peter?

[Peter M]

 

"Bruce, what do you recommend owners do when they bring in an otherwise well running car that just happens to have one broken stud like Nate's?"

 

Bruce, Bruce, where are you?

We're starting to talk 928's and now way of track, save this thread please!

[Stew F]

100% will ultimately fail. But the question is over what period. 100000km, 300000km, 500000 km. I'm going load the mechanical properties of Dilvar P1 into my software, and run a simulation.  But it will be a bit speculative because of the number of variables associated with trying to simulate how a particular engine will be used over it's lifetime.  How many heat cycles, combined with combustion cycle stresses, will it take to snap one of those little suckers? This is going to be interesting. Place your bets ladies and gentlemen.

[tazzieman]

Haha!

Just ordered diaphragms to repair my 928 HVAC system ; have to pull the dash apart hahaha. I have no fear of old Porsches but tiny hands would be an advantage.

[Peter M]

How many heat cycles, combined with combustion cycle stresses, will it take to snap one of those little suckers? This is going to be interesting. Place your bets ladies and gentlemen.

Corrosion seems to be key influence and that's why they changed the coating on the later dilavars. Not sure how you would model that. 

In fact the 993TT dilavars have got a strong fan base and are the recommended upgrade for the early mag case engines if you're of that camp.

My favourite head stud thread:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/930172-raceware-studs-911e-engine.html

 

[Stew F]

Corrosion seems to be key influence and that's why they changed the coating on the later Dilvarses. Not sure how you would model that. 

In fact the 993TT dilvarses have got a strong fan base and are the recommended upgrade for the early mag case engines if you're of that camp.

My favourite head stud thread:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/930172-raceware-studs-911e-engine.html

 

just another one of those pesky variables. I'll just have to dumb it down, so to speak.

[ANF]

 

I would doubt me Adam as I got it slightly wrong!

Hans-Peter Bauerle, Weissach Test Engineer actually says in Leffingwell's Porsche 911 - 50 year book that "the bottom line to get the car freed for manufacture was that it must run 8,000km around the clock with no problem [on their test track].  Which is the equivalent of 180,000km on normal road..."

 

That sounds like it would be a minimum and surely you could expect more than that on average?

 

Bruce, Bruce, where are you?

We're starting to talk 928's and now way of track, save this thread please!

Never heard of a 928 breaking a head stud (please if they have keep it to yourself )