M/T - Displayed Coolant Temperature Too Low
911 (997) 328/11 ENU 3477
Apr 7, 2011
The present document was valid at the time of print. A later version may be available online
Unnecessary Replacement of Coolant Regulator and Temperature Sensor (28/11)
Tools
Model year: as of 2007
Information
^ Document with limited validity
This Quick Information is valid until March 1, 2013
Vehicle Type:
911 GT3 (997)/911 GT3 RS (997)
Concerns:
Disc valve on transmission
Information:
Unnecessary replacement of coolant regulator and temperature sensor
With regard to the customer complaints
^ Displayed temperature too low
^ Display only works sporadically
and the following fault memory entries in the DME control unit
^ P2181 - Thermostat stuck open
^ P3081 - Engine coolant temperature implausible
We are getting more and more reports that the coolant regulator and/or temperature sensor is being replaced.
These problems can occur independently of each other - depending on driving style and geographic region.
The main cause is a blocked disc valve; -arrow- (illustration shows the position of the disc valve on the transmission).
An indication of a defective disc valve is also if the oil temperature and coolant temperature are almost identical in the warm-up phase. As a rule, the coolant temperature should be higher than the oil temperature.
Deformation of the sealing ring -arrow- can mean that the function of the disc valve can no longer be guaranteed (Figure 2 shows a cut-out view of a disc valve; arrow = correct position of the sealing ring). As a result, an additional cooling circuit is opened via transmission cooling in the warm-up phase and the engine is slow to reach operating temperature.
Action Required:
In the event of a complaint, check the disc valve (visual inspection and function test) before replacing the coolant regulator and/or temperature sensor.
Only remove and check the disc valve when the engine is cold.
Parts Info
Tools
Work Procedure:
The disc valve must be removed for the test.
Only carry out the following procedure when the engine is cold.
1 Removing disc valve
1.1 Remove underbody panelling, 519419 Removing and installing cover for rear underbody.
1.2 Clamp off water supply and return hoses using hose clamping pliers ahead of the disc valve and after the transmission oil cooler.
1.3 Remove hose clamps and vacuum line between the vacuum unit (disc valve) and change-over valve and loosen screw (disc valve at sheetmetal holder).
1.4 Remove disc valve.
2 Visual inspection
When the disc valve is removed, you will be able to see during a visual inspection whether the disc valve seal is deformed and whether it is positioned in the correct groove.
2.1 Hold the disc valve against the light and look into one of the two water hose adapters.
2.2 If the seal is no longer in installation position, you will see parts of the seal at the inner wall of the adapter.
Is the seal in its original installation position?
If it is: => Step 3
If not: => Step 4
3 Function test (approx. 0.1 quart of water required for this)
3.1 Turn the removed disc valve in your hand so that the black adapter is facing upwards.
3.2 Move the disc valve over the joint rod with your hand until it is in "Closed" position and hold it closed with your hand.
3.3 Check the disc valve for leaks:
To do this, fill water into the upward-facing open adapter.
Does water come out of the opposite adapter?
If it does: => Step 4
If not: => Step 3.4
3.4 Disc valve is not leaking.
Install the disc valve in reverse order to removal.
Check the coolant level and correct it if necessary. -> 193817 Draining and filling coolant (includes bleeding).
3.5 Work through the fault codes using "Guided Fault Finding" in PIWIS Tester II.
End of action required.
4 Replacing disc valve
4.1 Replace the defective disc valve.
Install the disc valve in reverse order to removal.
Check the coolant level and correct it if necessary. -> 193817 Draining and filling coolant (includes bleeding).
4.2 Work through the fault codes using "Guided Fault Finding" in PIWIS Tester II.
End of action required.
References:
-> 519419 Removing and installing cover for rear underbody
-> 193817 Draining and filling coolant (includes bleeding)
-> 195800 Unnecessary replacement of coolant regulator and temperature sensor (28/11)
997810, 997811, 997850, 997851
Model year as of 2007
C02, C36