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Gibbo205 said:GT4 said:bazhart said:GT4 - I am really sorry to have taken this on because you usually are so helpful and provide interesting answers usually quire rightly. I don't like arguing with those I respect on here but on this occasion - something is all wrong - and I cannot understand why - you are too clever to be pushing out this sort of stuff and I DON'T BELIEVE THAT YOU THINK IT IS RIGHT EITHER.
Please explain that IF the bearing is not up to the job - why then can we fit a new bearings of the same specification, not re-fit a seal, fit a stronger spindle (just because the old one is so weak in design it is a disgrace breaking all the notch rules for metal fatigue failure taught at colleges and universities Worldwide) and find that ever since they have all performed perfectly - hundreds of them? despite the fact that we are fitting them to older engines with worn parts in some areas (where customers do not want or cannot afford to replace all of them) and they still work just fine. If it is all to do with oil, toraional stress, revs, owners etc - how come just removing the seal fixes it?
Remember the other end just runs as a plain shaft running in an aluminium hole. I agree it only has one chain that end (not two) but that never gives any problems and being the other end of the same shaft has all the same torsional loadings as its opposite end.
I think your logic is misplaced on this and our experiences prove ours works and works better than the original design - for basically just replacing the same bearing without a seal. We even replaced the double row bearing with the single row one fitted to later cars (which is actually slightly stronger due to deeper tracks) together with a spacing kit and they are all OK too.
The proof of a solution is in the experience of it working or not - it works when the seal is removed - it doesn't if it stays in place.
My comment was sarcastic - sorry - but in the light of all the pading - I thought it a little obvious to state that it is better to have oil in the engine than not. I am sure that even those that run around with low oil know that and they didn't let their oil run low because they think it is OK - they just don't think or couldn't care less. For me it was stating the very obvious - somethingwe could all do and fill pages of answers - to no ones benefit.
Thin oil when hot also sqeezes out of all the tensioners and tappetts quicker (under the load from engaged tappetts and chain tension) than thicker oil - so when you switch off - loses more oil and pressure and on start up renders the car with more work to do to fill and support the loads. Tickover loads are negligible and by the time most people are motoring their cavities are full anyway and the car is running on full pressure.
Where did you get these explanations from - are they your own assessment or are you reading it from something someone else wrote on the subject?
Furthermore - If thin oil is so good why do all racing engines run thicker oil?
Even furthermore - if piston clearances new are OK for thin oil - after say 40K when they have increased by about 0.1mm - by what logic can the same oil be the best?
Usually - it is a difficult situation to criticise Porsche when their reputation was so good. Even when they made other errors that tuners fix - the general public are often sceptical about the solutions that small businesses provide (even though they are usually right). But in the case of these engines - with known problems with IMS bearings, "D" chunk failures, scored bores and pistons etc by what standards or logic can a conslusion be reached that they are always right when small businesses with comparatively limited resources can quickly see the p roblem and provide a solution that is proven to work and solve the problem and on that basis - from which stand point can anyone argue they are wrong and Porsche was right and if so why should any other of their publicity about oil grades and IMS failure causes be given any credence?
Did you also read my recent point reproducing all the benefits claimed by Porsche for their closed deck Mk2 997 engine design and my comment as to why - in that case - if it is so good - was it not fitted to the earlier models manufactured for 13 years when we managed to do so to the very first engine we saw - having imediately identified the problem.
If we can see a problem that they did not and fix it - why - when it comes to the IMS bearing - all of a sudden are Porsche right about it all and not us - especially when ours works and theirs often didn't?
You don't need to waste time replying on this - you got it wrong mate - you cannot win your argument - and the best thing to do is let it drop and pick up on something else where your input is usually so valuable.
One failure against so many good and valuable postings is not something to worry about.
Baz
I think I covered the fact my post does not vouch for the bearing quality or not, but only the affect of oil viscosity on the system the bearing is in.
Yes, my nan could do with a new heart valve, but instead of the cost and risk associated with a cure, she just doesn't run up and down stairs.
All owners who have an M99/97 engine have the IMS risk, my advice is just to help preserve it before is needs open Hart surgery.
But your advice is going against what others have said.
The advice to preserve the IMS is to use 5W-40 instead of 0W-40 and perform more frequent oil changes.
Your saying its better to use 0W-40, wheras Hartech, LN Engineering amongst others say 5W-40 is better.
So the question is who is right?
You do realise an oil such as 5W-40 has more wear prevention than say a 0W-40 oil yes?
As its the bearing in the IMS which is the issue, its all about preventing the wear of that bearing, which a 5W-40 does better than a 0W-40, yet your suggesting otherwise.
Also I did not suggest using different oils during Summer/Winter here in the UK, our climate is not cold enough to warrant using such thin oils and I am fully aware oil is not like a switch as such why in the UK as our winters are rather mild and our summers just warm the same oil all year round is fine. But in more extreme climates they either run a thinner oil or change to a thinner oil for winter.
I have been asked if it is better for a M96 or M97 engines (that's the standard 986,996,987.1 and 997.1 blocks) to run high viscosity oils, like 10w40.
hartech said:Thanks for that JM1962 I suppose it is only fair for you to point out that my description was not 100% accurate although I don't think it adds anything to understanding the events or causes I was describing.JM1962 said:Baz
Not wishing to be picky, but when the coolant boils it forms steam bubbles not air bubbles.
In my defence - unfortunately if I explained all the engine problems on here in the correct technical way without any background or analogies that enabled less well qualified people to follow the salient points - fewer people would benefit (and to be fair I have not noticed any other contributor covering anything like the technical issues I try to convey to the public to empower them to understand them if they need to or help them make informed choices to protect their interests). I try to find a balance between simplifying things and being correct so the majority benefit from being able to understand the issue - but this is always dangerous - as your posting demonstrates.
For your benefit (if I remember my schooling of 40 years ago correctly)
Coolant behaves like water and as such has different states from frozen to gas and in the middle steam. There are two types of steam - vapour and superheated steam (which is a gas).
Vapour is difficult to explain because it has lower density than liquid and hence increased volume. The problem is that increased volume of coolant (as steam bubbles) pushes coolant out of the expansion cap - so next time after it cools there is less coolant left inside and it doesn't neccessarily reach the same running pressure hence can boil/release steam bubbles/air bubbles whatever at a lower temperature than before and decrease the cooling potential at the source - the cylinder wall.
Fourty years ago we did not study atomic science much or molecular thoeory - but nowadays it is built into the education system from a very early age - a much better way of dealing with such issues.
If you understand this better than me I would be interested to learn exactly what steam vapour consists of. You are right it is not "air" bubbles because steam as a vapour is tiny droplets of water (or coolant) which I think must then be mixed in with with a gas (since the density reduces). But the gas will not be air because it has been formed from H2O - so is I suppose some form of a mixture of Oxygen and Hydrogen (whereas air is mainly Nitrogen - 78%).
It would be interesting to have this clarified but - in terms of helping readers understand the issues so they can decide for themseves what to do in the future to protect their interests or what questions to ask of their chosen repairer before commiting a rebuild or investigation somewhere that has limited options - I don't think whatever this gas is - makes any practical difference.
Rimmer said:Hmm so who's advice would I take.
1/ Baz who repairs 911's day in and day out and who has invested vast sums of cash in solving engine problems.
2/ GT4 a keyboard mechanic? IMO.
No contest as far as I can see