Lubrecon

I don't see how a bearing, with seals intact, could receive lubrication from the splashing of oil in a high revved engine. What am I missing here?

Ok, I'll agree that thermostats and IMS bearings are a long way apart, so I'll give it a rest on this tread about lubrication of bearings and yield to others with respect to thermostats and how they work!!

gpjli2

The OEM bearing was a grease packed unit. Some say the seal was to keep dust out during storage. It is considered to be a a poor application for an internal bearing by those studying the issue. Without the seal the bearing and spindle may have been ok with spray lubrication. On most higher milage engines the seal is compromised and some oil spray can infiltrate the bearing.This all is per the article I mentioned. I have no first hand knowledge here. I am not surprised this choice of application makes no sense to you. Porsche will never discuss this sort of thing for obvious reasons but warranties are running out on these motors. The failure rate is believed to be less that 5% overall (again quoting Total) with the more recent (post 04-05) units less failure prone due to some strengthing of the bearing (but it remained sealed!). This is why LN and some others have developed a replacement bearing assembly. I own an '06 w 27K miles on it and have no regrets. Hopefully that will not change.

Palmbeacher

You are dead wrong on all points. Clearly your ego overwhelms your knowledge and quashes your ability to accept the fact you are less than omnicient, so discussion with you is a fruitless waste of time.

As for others, I would suggest you consult with the nearest college or university with a mechanical engineering progam. Any first-year student will be able to confirm that the quotation above is rife with ignorant nonsense; and if needing further confirmation, simply go on up the chain through to the professors...of which I was at one time.

cbzzoom

More thoughts from Baz (Barry of Hartech) on the cooling issue :

http://www.pistonheads.com/gassing/t...20stats%20here!

cliff notes : don't slam on the gas when the engine is cold!

Lubrecon

Sorry Prof, I hope your toes heal quickly!!

Lubrecon

cbzzoom, very good reading. I wonder if Barry contacted any of those professors on this before he made his observations and conclusions about thermostats and engine overheating......nah, probably not, everyone knows real world experience is always trumped by professors who have the equations to prove that this cannot happen....kinda like greased and oil lubricated bearings....the one's with more room inside get grease, and the others get oil.....damn, there goes that ego thing again!!!

cello

Dude, chill... You are entitled to your opinion and to assert it with feeling. That said, however; RL, all forums, are for discourse; ie, we talk things out here not name call....

Thx for the info, again.

Regardless of opinions on what will work and what wont, I am thankful that there are independent engineering firms that are looking into aftermarket solutions to problems that are being experienced with these engines.

Porsche, in the age of mass tort lawsuits, cannot be the company of old. While that company stood behind its products, it also used early adapters as testing grounds. Those days are gone. Manufacturers now cannot admit fault and play 'shell games' with warranty claims so as to avoid large scale buy-backs, recalls, Toyota-like liability.

So, in real terms, its left to the companies mentioned in this thread and in the Targa 4S thread to listen to end users, investigate and diagnose problems, and work out real world solutions; and also to make avoidance recommendations on incomplete data.

Be thankful these guys are trying to create a market as if the very real, albeit low probability, problem(s) befall you these companies will likely be the only ones answering the bell.

And for those of us looking to possibly race these cars, these guys will be the main source of information how to preemptively avoid potential grenades..

My 0.02 cents, soon to be inflated to nothing...

Palmbeacher

In this case however I did not offer an opinion, I stated facts. Forums are not only for "discourse", they are also for education and enlightenment. Misinformation does a gross disservice to the community, whether it comes from well-meaning fellows like Lubricon suffering from Cliff Claven Syndrome, or crafty entrepreneurs taking advantage of laymen to further their financial agendas.

cello

^ I usually avoid this type of post but I think you have real value to add here so........

So you state, repeatedly. However, you provide no basis why your 'opinion' is 'fact' other than you so state.

If you want to join a forum of enthusiasts and have your opinion valued then I would suggest "showing your work" first to establish your bonafides. Otherwise, you are just another strong opinionated argumentative guy haunting the 997 forum where those types abound..

So, humor us, and give all the reasons why we should believe you, .. or don't. Either way, by the info you give shall your 'opinion', whether or not it is "fact", be judged. Thats the way it works on these boards populated by the anonymous..

ADias

I refrained from commenting on the topic at hand, a heated topic in many car forums, with strong opposing opinions. But, the cliff notes comment above... yeah, I agree with that.

Palmbeacher

Oh, bullsh!t. The fact that bearings designed to be grease-packed have greater internal clearance, if it isn't intuitively obvious to anyone with an IQ sufficient to have made enough money to afford a 997, can be verified by any automotive engineer. Like asking me for proof that Shaq is taller than Muggsy. Sheesh. If it matters to you, do your own research.

Lubrecon

Suspicions confirmed!!! Maybe Shaq and Muggsy can shed some light on the greased bearing question??? Boy, am I ever glad that I didn't have Palmbeacher for Thermo, Heat transfer, or Machine Design, or else I might be confused about grease and oil lubricated bearings also!!!

Lubrecon

Ok, enough of the "intutively obvious" stuff. Go here and see if bearing clearances are a factor when lubricating a bearing with an oil or grease. The only mention of bearing clearance is when a different grease was tried to solve the skidding problem. The replacement of the grease with an oil, was a direct replacement. The same bearing that was grease lubricated before is the same bearing that is now oil lubricated. I say again, bearings are not designed on the basis of what lubricating method will be applied to the bearing in the operation of that bearing. There is not one bearing for grease(greater internal clearance) and one bearing for oil(tighter clearance). So much for Professors!!!

http://www.machinerylubrication.com/...oil-lubricated

I will profess ignorance on that Shaq and Muggsy thing....hell, I don't even know who Muggsy is?????

cbzzoom

Yeah, it seems like it's really not that different from the early air-cooled Porsches, which had various flaws until people figured out the right mods and rebuild techniques to make them into reliable racers. There are plenty of years of old Porsches that you know need certain mods. Eventually we will have a set of procedures figured out for the M96/97 to address their issues.

In an ideal world, Porsche would be working with the amateur racers - groups like Spec 996 or Spec Boxster - to figure out what to do to their cars so that they are reliable to run in amateur racing, but so be it, we have to do it without factory help.

Some day I imagine that we will look forward to our engine breaking so that we have an excuse to get all the nice mods - get it bored out with new cylinder sleeves, get titanium bits so it can rev up to 8500, etc. just like with the old 911's. Something like a Tuthill 911 is way better than factory stock.

bazhart

If I could just add from the horses mouth that most of you have missed some of the reasoning in our buyers guide section 5 about what causes the scoring ( www.hartech.org buyers guide section 5).

The main culprit is changing to a common head gasket that fits both bank 1 and bank 2 and therefore do not balance the flow between cylinders as the 3.4 and smaller engined gaskets supplied in right and Left hand styles -do.

Secondly by increasing the proportion of coolant able to pass into the head they at the same time reduce the proportion going through the cylinders (so they inevitably run hotter) photos in the guide.

The long distance the coolant has to travel to and from the radiators, the thermostat being fitted on the way back (not from) the engine and the fact that these much more torquey engines are generaly driven at lower revs (because they are very quick there anyway) all contribute towards the slow response of an engine already running hotter than the guage implies.

We are seeing a lot of failures (ALTHOUGH STATISTICALLY LOW OVERALL) and two different piston faults.

Cars over say 50 or 60K can have the Molycote worn away and exposing aluminium on the piston face. Cars that fail sooner usually have flakes of Molycote missing (and some have both extremes). Rather like a non stick frying pan facing - the higher the temperature the sooner the coating peels and the less wear resistance it will have.

Since the scoring is relatively shallow we have successfully tested slightly oversized pistons (to avoid the need to replace the whole cylinder with an expensive liner - but just rebore it instead) and these will sooon be offered to our UK customers.

However when we fit these we also re-round and stabilise those oval bores (to improve piston clearance - reduce blow by and stop them cracking in future) and machine the cooling slots to increase the flow rate to the cylinders - so far with 100% success.

We have built two cars fitted with various temperature sensors (tested with different engine machining slots and thermostats) and know exactly what we are talking about regarding the in cylinder temperature gradients and effects and have tested both before and after scenarios with our early thoughts and prognosis proven in practice.

I guess driving style may have some influence because it is important not to suddenly rag the engine and also to keep revs up with high power and not allow the coolant speed from the water pump to fall too low (so driving a tiptronic fast best used in tiptronic not auto mode).

The cooling fan setting is not of concern as they only work in very slow or static traffic and as long as you gradually wind up performance when you hit the open road - and keep the revs up - it will quickly drop the temperature (although you may not notice this on the slow guage).

The method of setting the air con unit to record digital temperature is great to see what is actually going on and of course - while there seems a general acceptance on here that the cylinder temperatures are very high - no one seems to have noticed that if there was a leak from the rads or the cap - the running coolant pressure would be lower and this in turn allows bubbling and boiling at the sort of temperatures present - so care over the whole coolant system is essential.

Finally - although we would make more money fixing more failed engines - we regard the problem as so serious that we offer the low temperature thermostat to allow UK customers to avoid the problem (although this reduces our potential income). We bought in the low temperature thermostats from LN engineering (well done that business over there in the USA they are looking after your interests so trust them) and sell them at cost price - you see SOME BUSINESSES ARE ALSO ETHICAL AND CARE FOR THEIR CUSTOMERS - so no nasty sniping please. Indeed in the UK we post lots of advice about all these problems.

We are often accused of scare mongerring but all good maintenance relies on replacements or checks before a failure ever occurs and also all technical info allows owners to make informed choices about warranties, etc. Too many innocent owners expect their Porsche never to fail and find themselves in an impossible position in which the "Porsche solution" of a new engine destroys the equity in the car and many simply cannot afford that choice. Others get trapped by an expensive "investigative strip down" (when the business knows perfectly well from a simple camera check that the bores are scored) which then makes the alternative of a rebuild at an independent - more expensive).

Furthermore we have had some cars that have already had one engine replaced and have failed for the second time and they prefer a solution that at least addresses the basic flaws rather than dishes up more of the same.

We are not happy that so many UK customers have their expectations of the Porsche marque destroyed so easily but at least we try to offer an affordable solution, clear detailed information and also on top of all that an affordable warranty plan that will minimise the repair cost if an engine failed.

Baz