Water pump and thermostat life expectancy?

[wrinkledpants]

Picked up an 04 CTT, and the PPI revealed that there is a small coolant leak on the coolant pipes (they are aluminum). Car has 100K miles on it. In previous cars, the water pump was kind of a wear item that was replaced at about 100K miles. I noticed yesterday (I'm in Denver), that the coolant needle would move beyond what's normal, and the fans seems to kick into stg 2 speeds, but it was only 60 degrees outside (slow speed driving in the city). I've read this is normal since the cayennes don't smooth the temp readings like many cars do, but was thinking about doing the Pelican Parts Water pump kit (water pump, thermostat, upper and lower rad hoses, reservoir cap, and some Redline treatment) since I'm going to have to dig into the back to fix the coolant leak, and also do the T-fittings while I'm in there. In my 88 911, it was really apparent that the thin Denver air made for a tough cooling situation since oil temps would rise and remain high, despite having an oil cooler and aftermarket high speed fan. But, in the thick California air, temps remained rock solid when the ambient temps were the same as Denver.

Does the water pump and thermostat cause people a lot of problems on higher mileage cars? I think I may do it anyway, but if people don't see many problems with these two parts (at any mileage), I may elect to not replace them.

[JFP in PA]

Picked up an 04 CTT, and the PPI revealed that there is a small coolant leak on the coolant pipes (they are aluminum). Car has 100K miles on it. In previous cars, the water pump was kind of a wear item that was replaced at about 100K miles. I noticed yesterday (I'm in Denver), that the coolant needle would move beyond what's normal, and the fans seems to kick into stg 2 speeds, but it was only 60 degrees outside (slow speed driving in the city). I've read this is normal since the cayennes don't smooth the temp readings like many cars do, but was thinking about doing the Pelican Parts Water pump kit (water pump, thermostat, upper and lower rad hoses, reservoir cap, and some Redline treatment) since I'm going to have to dig into the back to fix the coolant leak, and also do the T-fittings while I'm in there. In my 88 911, it was really apparent that the thin Denver air made for a tough cooling situation since oil temps would rise and remain high, despite having an oil cooler and aftermarket high speed fan. But, in the thick California air, temps remained rock solid when the ambient temps were the same as Denver.

Does the water pump and thermostat cause people a lot of problems on higher mileage cars? I think I may do it anyway, but if people don't see many problems with these two parts (at any mileage), I may elect to not replace them.

Like many other "modern" Porsche water pumps, the Cayenne uses a composite impeller which will simply wear over time. This fact makes the pump a "maintenance item", meaning it needs to be changed proactively about every 4-6 years, regardless of what the cooling system is doing at the time. While swapping out the pump and thermostats makes excellent sense, I would skip the use of any coolant "additives" as they are short term Band-Aids that often degrade the otherwise excellent life expectancy of the Porsche coolant when it is mixed with distilled water.

[wrinkledpants]

Makes sense. I guess I'll do the full monty, sans the Redline stuff. So, are you saying that the actual impeller will get smaller over time, and it's ability to move coolant is why people run into problems where they are over heating? I've never fully understood how a bad water pump causes an overheat problem if the impeller is still spinning at the same speeds. I get how the leaks form, and I guess I could see a leak introducing air into the system, but never got how the water pump itself caused an overheat issue - mechanically speaking.

[JFP in PA]

Makes sense. I guess I'll do the full monty, sans the Redline stuff. So, are you saying that the actual impeller will get smaller over time, and it's ability to move coolant is why people run into problems where they are over heating? I've never fully understood how a bad water pump causes an overheat problem if the impeller is still spinning at the same speeds. I get how the leaks form, and I guess I could see a leak introducing air into the system, but never got how the water pump itself caused an overheat issue - mechanically speaking.

The water pump failure process is fairly well documented, the composite impeller starts to break up over time, reducing the system's efficiency as well as clogging small passages in the cooling system. While this is a pump out of a 30K miles 996, it illustrates what happens over time (and this one is only starting to fail):

If you have access to the Excellence magazine, there is an in depth discussion of how this happens starting on page 36 of the May 2014 issue; it is in the "Tech Notes" letters section in a letter titled "Anxious Pump Watcher".

[wrinkledpants]

Don't have access to that magazine, but that's a bit starling about the pieces floating around in the system. If you do take the water pump out, find it's missing pieces, how do you go about getting them out of the system? Or is that something you just hope it comes out or hope it's not plugging an important passage? The blocked flow to a turbo wouldn't be good :(

When I get mine pulled up, I'll throw up some photos if it's missing pieces.

[JFP in PA]

Don't have access to that magazine, but that's a bit starling about the pieces floating around in the system. If you do take the water pump out, find it's missing pieces, how do you go about getting them out of the system? Or is that something you just hope it comes out or hope it's not plugging an important passage? The blocked flow to a turbo wouldn't be good :(

When I get mine pulled up, I'll throw up some photos if it's missing pieces.

When the bits go missing, extensive back flushing of components is required to try and get it all out. That is why proactive replacements are mandatory.

[wrinkledpants]

Just reading about that now on the 996 forum. That's crazy. Does anyone make a metal water pump? Pelican lists 2 other manufacturers other than OE.

[JFP in PA]

Just reading about that now on the 996 forum. That's crazy. Does anyone make a metal water pump? Pelican lists 2 other manufacturers other than OE.

You really do not want to use a metal impeller pump; the gap between the impeller and the alloy engine case wall is quite small, and eventually the pump bearing will wear causing the shaft to wobble, and the metal impeller will start "machining" the alloy case, which will quickly do irreparable damage to the engine case as well as filling the cooling system with finely ground metal. That is why Porsche uses a composite impeller.................

[wrinkledpants]

Good point. I'll just stick with OE and consider it a wear item. Doesn't look overly tough to replace, anyway. Thanks for the help.

[JFP in PA]

Good point. I'll just stick with OE and consider it a wear item. Doesn't look overly tough to replace, anyway. Thanks for the help.

Anytime........................

[ekstroemtj]

Would like to place one additional question.

I just replaced the big cooling fan some weeks before. Now in city Traffic the Temp is going beyond 220F without putting the fan in Stage 2 running. What could be wrong? How to find out if my Thermostat is gone? Thank you for any input

[JFP in PA]

Would like to place one additional question.

I just replaced the big cooling fan some weeks before. Now in city Traffic the Temp is going beyond 220F without putting the fan in Stage 2 running. What could be wrong? How to find out if my Thermostat is gone? Thank you for any input

 

The fans can be tested using a Porsche diagnostic tool to see if they are running correctly or not.  I would start there.

[wrinkledpants]

Can you test them with durametric?

[JFP in PA]

Can you test them with durametric?

 

If you are referring to the electric fans, yes, you can switch them on with the Durametric software.

[icebird757]

how do you do it with the durametric ? 

 

and EKSTOEMTJ did you fix this issue with 220 degrees ?? 

[JFP in PA]

how do you do it with the durametric ? 

 

and EKSTOEMTJ did you fix this issue with 220 degrees ?? 

 

For a Cayenne, I believe it is under the A/C section (I am away from the shop at the moment).

[ekstroemtj]

how do you do it with the durametric ?

and EKSTOEMTJ did you fix this issue with 220 degrees ??

Not yet. Before i go back to my Local Porsche Service i wanted to see if i could find out something by myself.

I phoned the mechanic and asked if they made a Test when they replaced the new fan. He told me they did.

Saturday water temp was really high and SURPRISE, fan running on Stage 2. but i was expecting that fan will continue to run fast even when i park the car. They didnt.

I never had a loss of coolant when i checkend the CET in the past. This saturday the cooling Level Warning light came up.

Dont know what to think about this story again. Air in the System - maybe

Warterpump- cant see any coolant there

Thermostat- possible to check? How?

Coolant Tubes- are already changed for alu.

I keep you Updated whats going on

[ekstroemtj]

how do you do it with the durametric ? 

 

and EKSTOEMTJ did you fix this issue with 220 degrees ?? 

 

hi again,

 

for now i believe the main reason for the high temp was a air bubble in the cooling system.  i had to refill arround 0,60 liter of coolant. since that time the temp stay arround 80 degree celsius in the middle of the gauge. if its going a bit further, fan is kicking in with high speed.