Overheated, fans not coming on.
09-08-2018, 01:05 PM
#16
Chronic Tool Dropper
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The thermostat isn't "stuck" closed, it -IS- closed because it hasn't seen hot water yet. Please follow exactly the guidance I shared in post 9 above. I've been in your situation multiple times. You need to push out the air that's trapped in the water bridge above thermostat. Then the thermostat will open when the hot water hits it. It's as simple as that.
09-08-2018, 07:46 PM
#18
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..the air naturally clears the system pretty good while operating...I also think too much is being put into how to clear that.
Why the flaps and fans are not coming on...is the big issue.
Why the flaps and fans are not coming on...is the big issue.
09-08-2018, 08:00 PM
#19
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Halt the procedure at any point when the thermostat opens and the fans run. As I said I'm 50/50 on the air clearing with just a little engine revs and keeping the reservoir FULL as the system heats up the first time, vs. needing the extra steps like squeezing the top hose and bleeding the air out of the top of the radiator. OP may want to "vent" the engine end of the lower hose too, to clear the vapor lock that happens there until the thermostat opens the first time.
Get the hot coolant to contact the thermostat. That's the key.
Get the hot coolant to contact the thermostat. That's the key.
09-08-2018, 10:55 PM
#20
Ok....: I jacked the rear of the car as high as I could, filled the reservoir to the top. Started the car with the HVAC selected to the highest heat setting, burped the top Rad hose, rev’d the engine. I let the coolant temp indication reach the top white band and no go. The bottom Rad hose stayed cold and the fans didn’t come on. The flaps did operate correctly though, they opened all the way.
09-09-2018, 12:55 AM
#21
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Never had any trouble burping mine - usually finish it off with nose as high as possible to get air out the radiator bleeder. Bottom hose not getting hot says water not flowing doesnt it?
jp 83 Euro S AT 57k
jp 83 Euro S AT 57k
09-09-2018, 09:09 AM
#22
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What is the ambient temperature when this testing is being done?
What method/mechanism is being used to verify, during each test, the assumption that the engine water temperature has surpassed the thermostat opening temperature?
What method/mechanism is being used to verify, during each test, the assumption that the engine water temperature has surpassed the thermostat opening temperature?
09-10-2018, 06:57 AM
#23
Team Owner
FEIW the 928 has a self bleeding cooling system no need to jack the car to remove air pockets keep it on level ground
open the heater to full hot
fill the coolant bottle till the level stays constant
with the cap off run the engine till the fans come on
put on the cap drive the car for about 5 miles with heat on
park it and let it cool
top up the coolant
the system should now stay at half way on the coolant tank
open the heater to full hot
fill the coolant bottle till the level stays constant
with the cap off run the engine till the fans come on
put on the cap drive the car for about 5 miles with heat on
park it and let it cool
top up the coolant
the system should now stay at half way on the coolant tank
09-10-2018, 09:26 AM
#24
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Despite saying that I have set the car on a slope nose high in the past to remove air pockets, MrMerlin's process above worked last time I changed my coolant - overflow sits reliably at half full when cooled down from a run.
jp 83 Euro S AT 57k
jp 83 Euro S AT 57k
09-10-2018, 01:44 PM
#25
It's fixed ! On Sat I went to the local Porsche dealership and bought a new thermostat. When I was replacing the old thermostat I noticed a large amount of mineral/calcium deposits, I'm guessing the PO didn't use distilled water. I flushed the Rad quite a few times, threw in the new thermostat and everything runs as it should. The lower Rad hose now gets hot, the fans come on and the flaps operate as they should. Thanks for everyones input. Glad to be back on the road.
09-10-2018, 08:26 PM
#26
Team Owner
I hope you also replaced the rear t stat seal as these will also cause cooling issues