Water Temp Gauge markings
Posted: Fri Feb 24, 2006 4:03 pm
Inspired by a post on the S2forum, I think I might have worked out what the scaling on the water temperature represent.
I looked through the workshop manual and confirmed that the normal operating temperature of our cars is between 85ºc and 105ºc. I also found out that the MFTS (F76) puts the car into low boost mode when the engine temperature reaches approximately 118ºc and puts in back into normal boost mode once the temperature drops to approximatley 113ºc.
This got me thinking about the 3 little dots on the water temperature gauge just below the notches (see photo below). The first dot after the 50ºc mark could represent 85ºc (i.e. bottom end of normal running temp) with each notch thereafter representing a 1ºc increment up to 90ºc. After the 90ºc mark each notch could represent 3.75ºc which would take you to the 120ºc mark. Using this scaling theory the second dot could represent 105ºc (i.e. top end of normal running temp) and the third dot 113ºc could indicate where the MFTS does its boost controlling thing.
If this is correct it is a very bizarre and un-german way of marking up a gauge.
Based on this theory, my new 87ºc thermostat sits at just over 88ºc at speed which sounds about right and hopefully it means that many cars are not running quite as low temps as originally thought.
Incidentally, I also found a comment in the RS2 workshop manual stating the reason for the modified coolant hoses that fixes to the thermostat in the in the RS2 was to provide an "additional outlet for coolant expansion". The manual also confirms that expansion tank filler cap must have a functioning pressure relief valve that releases between 1.2-1.5bar. You can apparently pressure test the cap but also if it doesn't rattle the release valve may be stuck
Angus
I looked through the workshop manual and confirmed that the normal operating temperature of our cars is between 85ºc and 105ºc. I also found out that the MFTS (F76) puts the car into low boost mode when the engine temperature reaches approximately 118ºc and puts in back into normal boost mode once the temperature drops to approximatley 113ºc.
This got me thinking about the 3 little dots on the water temperature gauge just below the notches (see photo below). The first dot after the 50ºc mark could represent 85ºc (i.e. bottom end of normal running temp) with each notch thereafter representing a 1ºc increment up to 90ºc. After the 90ºc mark each notch could represent 3.75ºc which would take you to the 120ºc mark. Using this scaling theory the second dot could represent 105ºc (i.e. top end of normal running temp) and the third dot 113ºc could indicate where the MFTS does its boost controlling thing.
If this is correct it is a very bizarre and un-german way of marking up a gauge.
Based on this theory, my new 87ºc thermostat sits at just over 88ºc at speed which sounds about right and hopefully it means that many cars are not running quite as low temps as originally thought.
Incidentally, I also found a comment in the RS2 workshop manual stating the reason for the modified coolant hoses that fixes to the thermostat in the in the RS2 was to provide an "additional outlet for coolant expansion". The manual also confirms that expansion tank filler cap must have a functioning pressure relief valve that releases between 1.2-1.5bar. You can apparently pressure test the cap but also if it doesn't rattle the release valve may be stuck
Angus