Just fitted new Temp sensor, reading too high?

[zxtrevr]

Just fitted a new 3pin-grey temp to my 80 2.0E B4 to get the temp guage working, because It hasn't worked since i got the car last October, fitted it and its reading at 110oC all the time when it should be 90oC. The fuel guage is also unreliable, it jumps up and down. Been reading a few posts here and think it might be a voltage regulator behind the dash, but where abouts and how do you test it.

Wouldn't the engine would have blown by now if it was really running at 110oC all the time, it does at least 350 mile per week.

[stuartmmcfc]

when you say "all the time" , is that even when its first switched on and cold?
coulkd be a short in that case??

[pimpdriver]

I got a similar problem on my 100.

I changed the radiator, the radiator is off a turbo car so is 1 inch wider.

I swapped over the temperature sensor screwed into the rad, so I am using the correct 2 pin one.

It reads low all the time, but the heater works fine, the coolant gets hot, and the fan kicks in after caning it.

I think the MFTS might be the cause (Multi Function Temp Sensor).

[pimpdriver]

also, if it does everything it is supposed to do (ie heater works, coolant hoses get hot, rad fan kicks in), it sounds like dodgy instrumentation

Sorry, don't know how to test voltage reg.

[zxtrevr]

it just rises when engine is running normally, stays down when cold.

[urS6]

Originally Posted by zxtrevr

Been reading a few posts here and think it might be a voltage regulator behind the dash, but where abouts and how do you test it.

http://www.humanspeakers.com/audi/cluster-T89.htm might be helpful - it shows where the voltage regulator is on a 89 90q.

From memory, the regulator is a three pin chip with a metal heatsink - one pin is 12V (rising to 13.8v when the alternator is running), one pin is 0V, and the third pin is a constant 5V. Check with Bentley or Haynes.