cooling fan problem

[thor1974]

i have a 2006 Cayenne 4.5 bi-turbo. i notice that the cooling fan run only on low speed. had the Porsche how the Touareg and Q7 a dual thermo switch and how i can test the low and high speed mode?

 

Please help

 

[JFP in PA]

I think you may find that the main cooling fan speed is pulse width modulated, meaning the fan motor speed is infinitely variable by PWM electronic control; so there is no low and high speed.

[thor1974]

the cooling fan spins all time with the same speed. my problem is that the temperature goes a little about 180 and the water comes out by the reservior then the fan kicks in and everything is ok. thermostate waterpump headgaket is all new.

[thor1974]

the wire diagram shows that 2 cable goes to the DME so i think it had no high speed?

[Loren]

The speed is controlled by the DME - which means the DME runs it as fast as needed to properly control the cooling.

In the older cars, you only had high speed or low speed -- so now you have variable speed control. The variable speed will minimize temperature spiking between settings.

[thor1974]

how i can check the speed control?

[thor1974]

can be that the DME is defect?

[JFP in PA]

20 minutes ago, thor1974 said:

how i can check the speed control?

 

The speed control is solid state and built into the fan motor itself.  I believe that a PIWIS unit is capable  of testing the system.

[JFP in PA]

16 minutes ago, thor1974 said:

can be that the DME is defect?

 

I would seriously doubt that, if the DME had a problem, the system should throw a code.

[Loren]

From the Porsche Technical Book on operation...

 

[thor1974]

i filled the Water reservoir until the max. mark. the max. was still above the water. i start the engine and after the temperature went up to 180F the thermostate open and the temp went down to 170F. after a while the temp goes up until 190-195F and before the Fan kicks in the water is coming out by the reservoir. The Water is not boiling if i stop the engine water goes down to the mark again. i let the engine now running until the water came up and squeezed with my  hand the waterhose driverside which goes to the thermostate. after 3 times the water came up it stop and the water level is in the middle between min.  and max. maybe i had somewhere an air package??? i will try it tomorrow again and see what happen.

[thor1974]

so if i turn off the AC the temperature goes up and press the water out of the reservoir. if i have the AC on everything is fine.what could be the Problem ?defective waterpump or not 100% opening thermostat ?

[ekstroemtj]

Member @ lewisweller would ask: do you feel any smell of gas when you open the reservoir ? If not ok. If yes, head gasket.

You wrote thermostat is new? You installed it?  How the coolant was refilled? I bought a special vacuum refill tool because Cayenne V8 engines are well known for air pockets. Not just enough to put water inside until max. Reading.

When you sit in your car and watching the temp gauge climbing up, what happens with the temp if you rev the engine a little bit for one minute. Can you see the temp dropping?

 

[lewisweller]

thor 

The system will self bleed. You need to keep the fluid level at max and close the cap. Go for a drive and leave the AC MAX HEAT on to help prevent any over heating and circulate coolant all through the system and get air out. Just in case you do have a fault, keep a close eye on the gauge. 

After the drive leave the car overnight to completely cool down to cold. 

In the morning check the fluid and top it up to max again. Repeat this process until the level is correct. This is now completely bled and no air is left. 

 

For your info and as Loren posted, the fan will not kick in unless the coolant temp is higher than 93oC, but if the AC is on fans are running anyway. To ensure your thermostat water pump and fans are working correctly (assuming all air is bled from system already) you sit at idle with the AC off. The temp gauge should rise to the mark between half and 3/4 then the fan should kick in and the temp will drop to half way on th gauge, this sequence should repeat itself. 

If you live in a hot climate the gauge can also do this at highway speed also depending on engine load but must never go to 3/4 or above as this is overheating for sure. 

 

I've had head gaskets blow on mine and symptoms are fuel smell in coolant, air bubbles in coolant, coolant loss, overheating at idle which temp drops when revving the engine as coolant is circulated quicker away from the blown head area and through the system. 

 

Follow the bleed process and report back. Don't run the engine with the cap off!  it will overflow as water expands and the system is pressurised. You can how ever run from cold and squeeze the top hoses to bleed some air out BEFORE it gets hot but close the cap quickly before it starts to overflow. 

Good luck. 

 

[RFM]

The pressure cap (filling cap) on the expansion tank is in many cases a source of annoyance due to pressure loss, there are devices on the market to test this but a new one does not cost an arm and a leg and can fixes problems as yours. 

[ekstroemtj]

@lewisweller first time i dont agree with you Lewis. My first Indy did it exactly the same way like you discribed. Topping of is not enough IMO. 

[lewisweller]

29 minutes ago, ekstroemtj said:

@lewisweller first time i dont agree with you Lewis. My first Indy did it exactly the same way like you discribed. Topping of is not enough IMO. 

Your absolutely right Thomas. Vacuum bleeding is always the preferred method if available.