Water pump longevity ????

[WorkInProgressK]

Originally Posted by JFP in PA

Can't agree to eithier point.

We have run 160F stats on fully insrumented cars and consistenly found both lower coolant and more importantly oil temperatures when operating at steady state (cruise speeds). Coolant temps typically drop from around 205-210 to the mid to high 170F range. Oil temps drop 20-25F. Used oil analysis on cars befor and after adding the low temp stat showed the oil was in better condition after equivlant usage.

We have had multiple cars in the shop that had metal impeller pump failures that resulted in significant damage to the engine cases behind the pump. Several of these cars showed coolant circulation issues after being fitted because the new pump lost efficency due to the increased gap behind the impeller. Trimming impeller blades is a method to slow pump circulation rates, which is an old racers trick to improve high engine RPM cooling as usually the pump is moving coolant too much coolant under those conditions. But like everything else, there is a "too much" limit in doing this, when the reduced flow leads to over heating, particularly at lower engine RPM levels.

There are reasons the factory used compostie impeller pumps on these engines, and why they equip all of their high performance engines (turbos, etc.) with 160F stats from the factory.

JP, you are just throwing information that is not possible to measure easily and if you did, should have graphs and data showing it.

About the thermostat. You are measuring the temperature after the thermostat, not at the radiator. All 986s(without center rad) has the same thermal capacity. The only difference is that the proportion of the heat is located in the engine or in the radiator given the same amount of usage and type of usage. The delta temperature(difference between two values) will be different I agree, but it will not affect daily function or be worth it. All you will get is a car that is terrible to use in the morning when its 40-60F outside with much less cabin heat and increase emissions. Considering even california weather that is still half the time used as a commuter.

About the impeller damage. I would love to see pictures. Also considering the person who let a weeping pump long enough for the water pump to fail axially, they wouldn't see the difference in coolant performance anyway. Proper usage you wouldn't see major failures of the pump.

I am just trying show that people should look at a choice in the big scheme of things rather then facing specific problems. Lower Thermostat, under driven pulley, oil cooler, 3000 miles oil change on synthetic , great way to make money on people with more money then time to educate themselves on their car. Listening to "experts".

[JFP in PA]

Originally Posted by WorkInProgressK

JP, you are just throwing information that is not possible to measure easily and if you did, should have graphs and data showing it.

About the thermostat. You are measuring the temperature after the thermostat, not at the radiator. All 986s(without center rad) has the same thermal capacity. The only difference is that the proportion of the heat is located in the engine or in the radiator given the same amount of usage and type of usage. The delta temperature(difference between two values) will be different I agree, but it will not affect daily function or be worth it. All you will get is a car that is terrible to use in the morning when its 40-60F outside with much less cabin heat and increase emissions. Considering even california weather that is still half the time used as a commuter.

About the impeller damage. I would love to see pictures. Also considering the person who let a weeping pump long enough for the water pump to fail axially, they wouldn't see the difference in coolant performance anyway. Proper usage you wouldn't see major failures of the pump.

I am just trying show that people should look at a choice in the big scheme of things rather then facing specific problems. Lower Thermostat, under driven pulley, oil cooler, 3000 miles oil change on synthetic , great way to make money on people with more money then time to educate themselves on their car. Listening to "experts".

Again, I disagree. And I apologize that the shop does not take the time to prepare pretty Power Point presentations for you, but that is not what we are about.

The thermostat functions as a throttling device, restricting the volume of coolant returning from the radiators to the engine. As such, a lower temperature stat actually opens sooner (read at a lower temp) than the factory stat, so operating a vehicle with a 160F stat will actually get heat sooner than with an OEM stat. This is a common observation customers give us after changing over, and as we live in an area that often sees weeks of zero or sub zero temperatures, customers that use their cars as daily drivers would be screaming if there was a heat or warmup time issue. Yet in all the years we have been installing these stats, we have not had one complaint, only comments that is nice to get more heat sooner in the winter because the stat is opening sooner and allowing more warm water to circulate.

Metal impeller pumps do not have to completely fail in order to chew up the engine cases. There is only a few thousandth's of clearance between the impeller and the cases, and when these pumps start to wear and the impeller shaft starts to wobble, and they all do, the machining starts. We have had cars come in with complaints of seeping pumps, only to dump the coolant and find it full of finely ground aluminum, requiring us to flush the system to get all the metal out. And after installing a new pump and fresh coolant, the cars returned with complaints of running hotter than normal, particularly in warmer weather. A couple of these customers got annoyed enough about this issue to take the cars back to a dealer, who pulled the water pump, looked at the damage, and promptly told the owners that they needed a replacement engine as the impeller damage could not be repaired. They also confirmed that this is something they see regularly with metal impeller pumps, and why Porsche does not use them.

As for whether or not people choose believe, or even listen to what I have to say, that is entirely up to them. And quite plainly, I do not care if they do or do not choose to listen to us. Those that know me will tell you that I have never posted the name or location of my business online, or on any of the forums I either moderate on or participate in. We don't need any more business than we already have, we are doing just fine. We simply try to inform interested parties in what we have observed or experienced over some thirty years of building, racing, and repairing Porsches.

[WorkInProgressK]

Originally Posted by JFP in PA

Again, I disagree. And I apologize that the shop does not take the time to prepare pretty Power Point presentations for you, but that is not what we are about.

The thermostat functions as a throttling device, restricting the volume of coolant returning from the radiators to the engine. As such, a lower temperature stat actually opens sooner (read at a lower temp) than the factory stat, so operating a vehicle with a 160F stat will actually get heat sooner than with an OEM stat. This is a common observation customers give us after changing over, and as we live in an area that often sees weeks of zero or sub zero temperatures, customers that use their cars as daily drivers would be screaming if there was a heat or warmup time issue. Yet in all the years we have been installing these stats, we have not had one complaint, only comments that is nice to get more heat sooner in the winter because the stat is opening sooner and allowing more warm water to circulate.

Metal impeller pumps do not have to completely fail in order to chew up the engine cases. There is only a few thousandth's of clearance between the impeller and the cases, and when these pumps start to wear and the impeller shaft starts to wobble, and they all do, the machining starts. We have had cars come in with complaints of seeping pumps, only to dump the coolant and find it full of finely ground aluminum, requiring us to flush the system to get all the metal out. And after installing a new pump and fresh coolant, the cars returned with complaints of running hotter than normal, particularly in warmer weather. A couple of these customers got annoyed enough about this issue to take the cars back to a dealer, who pulled the water pump, looked at the damage, and promptly told the owners that they needed a replacement engine as the impeller damage could not be repaired. They also confirmed that this is something they see regularly with metal impeller pumps, and why Porsche does not use them.

As for whether or not people choose believe, or even listen to what I have to say, that is entirely up to them. And quite plainly, I do not care if they do or do not choose to listen to us. Those that know me will tell you that I have never posted the name or location of my business online, or on any of the forums I either moderate on or participate in. We don't need any more business than we already have, we are doing just fine. We simply try to inform interested parties in what we have observed or experienced over some thirty years of building, racing, and repairing Porsches.

I appreciate that you help the community. I won't argue that its the only reason why I keep participating. My field of work require thorough study of every situation and we can't forget the big picture. I am just trying to say that the solution isn't always clear cut. You might solve 1 issue and cause two problems. Just like IMS issues is to Porsche cutting cost on engine head castings .

As a friendly reminder, re-read yourself on the heater core part. Heaters(cabin radiator) and engine are on a closed loop system. No thermostat in between. In the morning, you will feel heat at around 100F on the cluster.

Originally Posted by kk2002s

Before low temp thermo, hwy cruising was right around 194 degrees, summer time.
With low temp, my summer temps run around 176 degrees. In the winter it runs 172 degrees. This is using the Torque app for water temp.
Now in stop and go the temp will move up in the 212-215 and the fans come on same as reg thermo. But cruising 50+ mph the temp definitely runs cooler.
Cooler is better

The result is the same(negligible error considering its two different test moments)... 176Fis 6Fto 170F and 194F is 8F to 186F. that 6-8F is the limitation of flow.

At max heat capacity(radiator at 212F), both thermostats should be open at 100%. ANY difference in flow here would mean one is actually better then the other. Under that situation you could say one thermostat is better then the other. Any other test in meaning less for a daily driver. Tracked Cars are a different story where you can tune the fuel and timing map to take advantage to the lower intake temperatures.

[JFP in PA]

Originally Posted by WorkInProgressK

I appreciate that you help the community. I won't argue that its the only reason why I keep participating. My field of work require thorough study of every situation and we can't forget the big picture. I am just trying to say that the solution isn't always clear cut. You might solve 1 issue and cause two problems. Just like IMS issues is to Porsche cutting cost on engine head castings .

As a friendly reminder, re-read yourself on the heater core part. Heaters(cabin radiator) and engine are on a closed loop system. No thermostat in between. In the morning, you will feel heat at around 100F on the cluster.

The heater uses a small bypass from the engine, but when the thermostat opens, more warm water is in motion within the cooling system and the engine, heat comes up in greater amounts within the cabin; so the thermostat does affect how much and how soon you sense heat coming from the car.

And, regardless of what you do for a living, it is never a good idea to look down your nose at anyone.......................

[paulofto]

Just an observation.

I've learned a ton from JFP and he has never steered me wrong. His experience with multiple Porsches over a long period of time has allowed him to see many, many more failure modes than any one of us will observe. The large sample size of cars he has been exposed too with & without low temp stats and with & without metal impeller pumps tells me his practical experience in this area carries more weight than the theoretical viewpoints.

One very real world piece of knowledge that JFP shared was to always use Porsche Brand MT fluid in the 6 speed. My thoughts were 'hell, gear oil is gear oil. It's all the same". Well I ignored JFP's advise, went with XXXXX brand and the shifting could only be described as s#itty. I drained it, put in the 'unicorn tears' oil from Porsche and it is 100% superb.

Like Jake Raby, JFP has seen it all. We would all do well to heed his advise when it is freely given.

[Pdwight]

Originally Posted by paulofto

Just an observation.

I've learned a ton from JFP and he has never steered me wrong. His experience with multiple Porsches over a long period of time has allowed him to see many, many more failure modes than any one of us will observe. The large sample size of cars he has been exposed too with & without low temp stats and with & without metal impeller pumps tells me his practical experience in this area carries more weight than the theoretical viewpoints.

One very real world piece of knowledge that JFP shared was to always use Porsche Brand MT fluid in the 6 speed. My thoughts were 'hell, gear oil is gear oil. It's all the same". Well I ignored JFP's advise, went with XXXXX brand and the shifting could only be described as s#itty. I drained it, put in the 'unicorn tears' oil from Porsche and it is 100% superb.

Like Jake Raby, JFP has seen it all. We would all do well to heed his advise when it is freely given.

I too have learned a great deal from JFP, couldnt agree more

[eicheldp]

Originally Posted by Pdwight

I too have learned a great deal from JFP, couldnt agree more

+1
JFP has provided much advice to this forum and others. In addition he has answered PM's from me when I first purchased my 986. I respect his knowledge and his generosity.