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herogenous

Cylinder Scoring - Cooling issues - Opinions - NEWB!

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Hi Everyone,

 

Newb alert - apologies if this is all nonsense!

 

Like a little enthusiatic (and paranoid) first-porsche owning bunny (and in order to try and best keep my recently purchase 996 C4S alive as long as possible) I've been trying to do as much research here and elsewhere on the more common engine health issues. It seems (to a newb like me at least) that the second most prevalent issue is one of bore scoring and oval pistons in the larger 3.6 engines (only). This article explains the problem in great, great, detail (albeit in a very, very long format! - 72 Pages!)

 

http://www.hartech.org/docs/buyers%20guide%20web%20format%20Jan%202012%20part%205.pdf

 

The short version of it (in THIS guy's opinion at least) is that a series of differences / inefficiences / changes / hot spots - localised boiling points in engine cooling and oil flow on the 3.6, particularly on the thrust-side of bank 2 cylinders, a higher cylinder wall pressure due to shorter con-rods in combination with bad driving habits and a few other factors all combine to create this problem.

 

Obviously, taking any one opinion would be very bad form, so I thought I'd see if anyone more mechanically minded than me had any thoughts on this? Furthermore, I have been pointed by a few people in the direction of this stuff as a generally good idea for the health of your car and specifically as part of a preventative measure for the issues mentioned above.

http://evanscoolants.co.uk/

 

The claims and logic seem rather impressive and has apparently been picked up by Honda and is now going into a lot of endurance racing engines etc. The benefits of a non electrically conductive, non oxidising, non boiling, low-expansion, non hot-spotting, low pressure coolant do seem very sensible on the surface, but I may just be lured by the claims.

 

Has anyone had any experience with it? Should I avoid it like the plague and stick to good old fashioned water derivatives? I do very much like the idea of taking water out of the equation which presumably should really help radiator issues and many other forms of degradation?

 

Many thanks in advance for your help and opinions!

Andy

 

 

 

 

 

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Andy,

 

I saw this used on the English TV show, "Wheeler-Dealers".  Ed the mechanic spoke highly of this product.

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Hi Everyone,

 

Newb alert - apologies if this is all nonsense!

 

Like a little enthusiatic (and paranoid) first-porsche owning bunny (and in order to try and best keep my recently purchase 996 C4S alive as long as possible) I've been trying to do as much research here and elsewhere on the more common engine health issues. It seems (to a newb like me at least) that the second most prevalent issue is one of bore scoring and oval pistons in the larger 3.6 engines (only). This article explains the problem in great, great, detail (albeit in a very, very long format! - 72 Pages!)

 

http://www.hartech.org/docs/buyers%20guide%20web%20format%20Jan%202012%20part%205.pdf

 

The short version of it (in THIS guy's opinion at least) is that a series of differences / inefficiences / changes / hot spots - localised boiling points in engine cooling and oil flow on the 3.6, particularly on the thrust-side of bank 2 cylinders, a higher cylinder wall pressure due to shorter con-rods in combination with bad driving habits and a few other factors all combine to create this problem.

 

Obviously, taking any one opinion would be very bad form, so I thought I'd see if anyone more mechanically minded than me had any thoughts on this? Furthermore, I have been pointed by a few people in the direction of this stuff as a generally good idea for the health of your car and specifically as part of a preventative measure for the issues mentioned above.

http://evanscoolants.co.uk/

 

The claims and logic seem rather impressive and has apparently been picked up by Honda and is now going into a lot of endurance racing engines etc. The benefits of a non electrically conductive, non oxidising, non boiling, low-expansion, non hot-spotting, low pressure coolant do seem very sensible on the surface, but I may just be lured by the claims.

 

Has anyone had any experience with it? Should I avoid it like the plague and stick to good old fashioned water derivatives? I do very much like the idea of taking water out of the equation which presumably should really help radiator issues and many other forms of degradation?

 

Many thanks in advance for your help and opinions!

Andy

 

To me, this product has always seemed like an expensive solution in search of a suitable problem.  We see literally dozens of liquid cooled Porsches every day in the shop, some with over 200K miles on them, and not one of them are using this "magic ingredient" as you describe it, and none of them are dying from liner scoring.

 

Long before I would head in the direction of "waterless coolant", I would simply cool the engine down a bit.  It is well documented that these engine's run way too hot to begin with, and that problem is further exacerbated by the creation of localized hot spots that are caused by the coolant flow restrictions inherent in the engine case castings.  The result is the general coolant flow is running at over 210F under good cooling conditions, with the localized areas running as much as 30F (or more) higher.  My first step would be to change the car over to a 160F thermostat (the OEM stat begins to open at 184F, but is not fully open until nearly 210F).  Just by doing this simple and relatively inexpensive change, we have seen car's coolant temps drop to 175F under the same conditions that they previously ran over 210F.  We have also observed a drop of 25-30F in the oil temperatures as well, which goes a long way in helping the oil do its job while living longer.  We have many customers running this configuration, and have done so for several years with absolutely no issues, and even their UoA's look better.

 

You cannot easily address the engine's inherent coolant flow restrictions, but by lowering the coolant temp and keeping the front radiators clear of any debris, you will go a very long way towards eliminating this issue.

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Thanks chaps! Seems like quite a divisive issue amongst even experienced engine folk!

 

JFP, I like the lower temp thermo option - is there a downside?... Is the thermostat change a diy job (for a reasonably engine minded person) and is there a specific part one should look for?

 

Cheers for humouring my newb qu's!

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Thanks chaps! Seems like quite a divisive issue amongst even experienced engine folk!

 

JFP, I like the lower temp thermo option - is there a downside?... Is the thermostat change a diy job (for a reasonably engine minded person) and is there a specific part one should look for?

 

Cheers for humouring my newb qu's!

 

As I noted, we have many customers running the 160F LN thermostat for years with absolutely no downsides.

 

Changing the stat is a matter of draining the coolant out, and removing four bolts.  Would also be an excellent time to replace the coolant if it is more than 4 years old.

 

Pic5.jpg

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Hi,

Ive just recently bought a 1998 996 and was worried about the same issues.  Ive given up worrying now.

Ive fitted the lower temp stat.  Engine use to run at 92-98+ degrees.  It now runs at 78-88 depending of traffic conditions.  The lower temp stat is a good cheap place to start some preventative maintenance. I'd also replace the coolant if there's no record of it being done.

Also make sure the front radiators are in good condition and not blocked up with leaves and rubbish.

 

I noticed my rads are in poor condition and 1 looks like its had radweld in it.  I think thats why mine still runs hotter that the thermostat temperature.

 

The climate control panel can be forced into a hidden mode to show true coolant temp, the cluster gauge doesn't tell the truth or mine doesnt anyway.

linky to get to hidden menu http://www.6speedonline.com/forums/996-turbo-gt2/180515-hidden-display.html

 

Dave

 

Apologies JFP in PA 

​I didn't read your post and you mentioned the lower temp stat :-)

Edited by DaveN996

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Cheers Dave and thanks again JFP - Sorry I missed the part num in your first post!. Great info - especially the secret hack!

 

Any concern about oil viscosity changes running at a lower temp or are the differences too marginal to notice? (I suspect so!)

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Cheers Dave and thanks again JFP - Sorry I missed the part num in your first post!. Great info - especially the secret hack!

 

Any concern about oil viscosity changes running at a lower temp or are the differences too marginal to notice? (I suspect so!)

 

The oil viscosity difference is marginal at best, but the lower oil temps is important to the oil's longevity and hear resistance.   What would also be important is selecting an oil with high ZDDP levels and film strength.

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I posted on Rennlist about this recently as a result of seeing an article in the Porsche Club GB magazine about cylinder scoring, which coincidentally promotes the aforementioned waterless coolant product (scanned version here.) It seems that on that side of the Atlantic, cylinder scoring is the Porsche killer whereas on this side, it is the IMS bearing. Assuming that cylinder scoring is indeed more prevalent there than over here, and isn't just a result of hype from certain vendors, I wonder if there is a plausible technical reason? The theory that I came up with is that virtually every engine in the UK is subject to the same climate, but in the US there is much more variation in climate. If there are more M96/97 engines in the US than in the UK, it stands to reason that any cold climate-related issues are going to be more prevalent in the UK. However, I given that that the engine, and in turn the coolant, operates at much higher than ambient temperature, I have a hard time believing that climate has any bearing on the situation.

 

As an aside, based on what I read about waterless coolants, it seems to be more commonly used in vintage cars and certain automotive-based aircraft engines (Rotax) The lack of water means no corrosion, which is beneficial in antique vehicles. However, while waterless coolant avoids the issue with traditional water-based coolant turning into steam at high temperatures, potentially causing cavitation, it is less efficient than water at removing heat. Therefore, the system will run hotter overall. I do not know if this matters in practice.

 

For my own car, a 2002 996, I plan to do a coolant flush with Porsche factory coolant dilute per the recommendation in the not too distant future. I have a small coolant leak that I need to isolate and may well take the opportunity to do the water pump, in which case I'll go for the lower temperature thermostat as JFP in PA suggests.

Edited by GromitInWA

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I posted on Rennlist about this recently as a result of seeing an article in the Porsche Club GB magazine about cylinder scoring, which coincidentally promotes the aforementioned waterless coolant product (scanned version here.) It seems that on that side of the Atlantic, cylinder scoring is the Porsche killer whereas on this side, it is the IMS bearing. Assuming that cylinder scoring is indeed more prevalent there than over here, and isn't just a result of hype from certain vendors, I wonder if there is a plausible technical reason? The theory that I came up with is that virtually every engine in the UK is subject to the same climate, but in the US there is much more variation in climate. If there are more M96/97 engines in the US than in the UK, it stands to reason that any cold climate-related issues are going to be more prevalent in the UK. However, I given that that the engine, and in turn the coolant, operates at much higher than ambient temperature, I have a hard time believing that climate has any bearing on the situation.

 

As an aside, based on what I read about waterless coolants, it seems to be more commonly used in vintage cars and certain automotive-based aircraft engines (Rotax) The lack of water means no corrosion, which is beneficial in antique vehicles. However, while waterless coolant avoids the issue with traditional water-based coolant turning into steam at high temperatures, potentially causing cavitation, it is less efficient than water at removing heat. Therefore, the system will run hotter overall. I do not know if this matters in practice.

 

For my own car, a 2002 996, I plan to do a coolant flush with Porsche factory coolant dilute per the recommendation in the not too distant future. I have a small coolant leak that I need to isolate and may well take the opportunity to do the water pump, in which case I'll go for the lower temperature thermostat as JFP in PA suggests.

 

Besides the obvious cooling system hot spots, the European weather can be a factor as repeated cold starts and shorter drive cycles lead to fuel intrusion into the oil which both washes lubrication from the critical trust side of the cylinders and reduces the effectiveness of the lubricants, as does the European penchant for putting a lot of miles on oil before changing it.  While such action is obviously "green" and environmentally friendly, it can lead to accelerated wear issues in alloy engines.  Add in the ever lowering levels of ZDDP in the oil and you probably have another contributing factor.

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Thanks GromitlnWA, I think you're right. It certainly does seem to be a genuine concern here, certainly Hartech have done a LOT of research into the issue and lots of cars SEEM to be coming in with the same symptoms. It is very, very possible though that this is caused by rich London play-boys in the UK (without any understanding of cars at all), jumping in their Porsches in winter and ragging the nuts of them from cold and this is just weakest point of symptoms. Although one other factor could be that there is a LOT of stop-start traffic in the UK... I mean a LOT - could this be a contributing factor?

 

Low revs, stop, start, stop, start.. Is there a rev count, below which lubrication is not happening properly? I suspect so. It wouldn't surprise me if cars spend a lot of time in the UK at 1500 or below in traffic.

 

JFP, re journey cycles... absolutely! A few 2 minute trips to the shop in freezing temps every week just can't be good - maybe I need to emigrate! Or take my GF's car for those short trips!

 

Actually JFP, I was going to post another thread on this but I think that's overkill. I don't know how au-fait you are with UK oil availability, but I'd be very greatful for your pick of the Porsche approved 5W-40 oils for my '02 C4S 70k miles 996!

 

Thanks again guys, especially JFP for the lightening quick responses... this really is a top forum!

 

Ps. On the waterless coolant... lots of conflicting opinions. Some say whilst water (in pure physics terms) is better at thermal transfer, the benefits of eliminating steaming and hot-spots actually outweighs this and keeps the car running cooler in general. Seems to me, like most of these things, nobody really has any definitive proof either-way and it's always mixed up with PR, marketing and endorsements. C'est la vie.

 

As JFP points out, it's an expensive "upgrade" if there are no real benefits!

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You will get as many opinions on oil as members on here ;) . Personally I use Liqui-Moly Syn 5w-40 at 5000 mile intervals. Changed over from Mobile 1 0w-40 and have noticed a decrease in the amount I need to add between changes

 

See full list here - http://www.pedrosgarage.com/Site_3/Porsche-Approved_Oils.html

Edited by BAD124

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Jake Raby, Flat 6 Innovations, recommends Joe Gibbs Driven DT40. His engine warranty requires its use.

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Can vehicles with scored cylinders be driven for a whilr as is, ensuring oil is topped off at all times? Will they eventually experience catastrophic failure?

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Can vehicles with scored cylinders be driven for a whilr as is, ensuring oil is topped off at all times? Will they eventually experience catastrophic failure?

 

Generally, no, more likely they would see a power fall off and increased oil consumption.

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