Using Oil Temp Gauge to Monitor Coolant Temp and Audi GT Website

[Alan Kramer]

Below is a submission that will be posted soon on the Audi 'Grand Touring' 
website (which you should check out if you haven't seen it yet  
http://www.metrocomputing.net/gtworld )

Subject:  Using An Oil Temp Gauge to Monitor Coolant Temperature for CGT's.

One thing that's always bothered me about CGT's are the lack of numbers on 
the coolant temp gauge.   I'd always wanted to add an extra oil temp gauge 
somewhere and have it register coolant temp., but the problem is the output 
from the coolant temp senders is different than what the oil temp gauges can 
read.

The oil temp sender for the early CGT's is a M18x1 fitting, and the later 
(2226cc) a M22x1.   All the coolant temp ports are M10x1 threads, so can't 
simply thread a oil T sender into a coolant port.  So one solution I'd 
thought of was to tee into a coolant temp and get a M10x1 to M18x1 fitting.

But there is a more elegant solution...  The 4 cyl. 4000's use a M10x1 oil 
temperature sender located on the oil filter mount.   For the '83 and 
earlier 4k's a 150C sender and gauge were used.  On the later cars, a 180C 
sender was coupled to a 170C gauge.   The 150C sender is P/N 049 919 563A 
and is white, one pin.  The 180C sender is 049 919 563B and is blue, one 
pin.  The A sender matches the oil temp gauge that runs from 50 - 150C, has 
the scale flat across the gauge (old style), and white backlight.   The B 
sender matches the oil temp gauge that is identical to the one just 
describes but goes from 60 to 170C and also matches the red-illuminated 
gauge from 60 to 170C that has the numbers in the later, arc style.

For my '83 I had the 60-170C oil temp gauge already in the car for oil temp. 
   I replaced my voltmeter (in fact I just moved it to my other triple gauge 
console in my drivers side cubby hole on the lower dash, with the 50-150C 
flat gauge.  This offered some visual difference between the two gauges so 
it didn't look like I had the same gauge in the same cluster twice.

I also had an extra M10x1 port in my coolant system when I moved the car 
over from CIS to CIS-E.   For those of you with CIS cars, you can pick up an 
extra M10x1 coolant port by replacing the metal flange at the upper radiator 
hose at the head with one from a '85 & later CGT or 4kq.  For those of you 
with a CIS-E car and no place to put an extra coolant port, one option is to 
replace the metal heater hose line from the back of the water pump  that 
runs parallel to the spark plug side of the engine with one from an earlier 
CIS CGT.   This contains a M10x1 fitting.  Either move your existing coolant 
temp sender to this location or use this one for your new gauge.   Another 
option for any year CGT is to get a M10x1 tee and M10x1 close nipple and 
screw this into any existing coolant port.   Maryland Metrics can supply 
these fittings cheap and they have a great web site at http://mdmetric.com

Screw the M10x1 oil temp. sender into your coolant port and run 1 wire from 
it into the car.   I have used the speedo. grommet to pass a number of wires 
thru the dash, and that's what I used in this case as well.  Replace your 
voltmeter with the new 'coolant' temp gauge.  You can either cut off the old 
volt meter wire fittings and crimp on 2 1/4" female wire terminals to supply 
+12V and GND to the gauge, or you can use Audi Connector 000 979 204 butt 
spliced onto the end of your wire from the temp sender and plug this 
directly into the factory wire connector.

You do not need to remove any of the dashboard.  Simply remove the radio to 
gain access to the back of the triple gauges.  This will save a significant 
amount of time.  I removed the cover from my gauge cluster to fish the wire 
thru the speedometer grommet in the firewall firewall (with the aid of a 
straightened coathanger).  This project took 1/2 hour to complete.

------------------------------------
Alan
http://www.geocities.com/audikramer

'83 CGT
'85 CGT turbo project
'86 4kcsq

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