Temperature Gauge issue

[Tartan58]

I've done a search on this but not come up with anything matching my specific problem:

I've had the car for 2 years and everything's been normal in all driving conditions however I noticed on saturday after about 1hr of steady motorway cruising (75ish on the cruise control) that the temp guage had dropped right down to minimum, no issues with the way the car was running.
So yesterday I was our driving around town and monitored "number 51" on the climate control panel which gives a digital readout of the coolant temp. The digital display showed the car warming up as normal to 90 then sat there no probs, the temp guage did go up as well this time but seemed to lag about 10 degrees below what the digital readout said (although did get up to 90 eventually and sit there fine)

I assume it's a temp sender problem of some sort, does the guage on the dash take it's reading from somewhere different than the digital readout?

Sorry for the long post, any ideas would be appreciated!

 

[Dai Rob]

My gauge went about 8 - 9 months ago with exactly the same symptoms as yours. Occasionally it comes back to life but, like you, I now rely on code 51 on the air con display.

From my checks it would appear that the temperature unit on my Tolly (130 / ASZ engine) comprises of a 'dual sensor' with two pairs of cables coming off it. One set go to the management unit and the other into the car to the dash / clocks area.

Either I have an intermittant wiring fault or the one side of the sensor is buggered. Either way, since the car is performing fine i'm not going to do anything about it..

Hope my waffling helps..

 

[burnsy_b]

I've done a search on this but not come up with anything matching my specific problem:

I've had the car for 2 years and everything's been normal in all driving conditions however I noticed on saturday after about 1hr of steady motorway cruising (75ish on the cruise control) that the temp guage had dropped right down to minimum, no issues with the way the car was running.
So yesterday I was our driving around town and monitored "number 51" on the climate control panel which gives a digital readout of the coolant temp. The digital display showed the car warming up as normal to 90 then sat there no probs, the temp guage did go up as well this time but seemed to lag about 10 degrees below what the digital readout said (although did get up to 90 eventually and sit there fine)

I assume it's a temp sender problem of some sort, does the guage on the dash take it's reading from somewhere different than the digital readout?

Sorry for the long post, any ideas would be appreciated!

its possible one of your temp sensors is on its way out. you have one in your exspansion bottle where you put your engine coolant and one in your actual radiator.

 

[Dai Rob]

its possible one of your temp sensors is on its way out. you have one in your exspansion bottle where you put your engine coolant and one in your actual radiator.

The unit in the expansion bottle is a switch used to set off the temperature warning lamp on the dashboard..

 

[Muttley]

burnsy_b wrote

its possible one of your temp sensors is on its way out. you have one in your exspansion bottle where you put your engine coolant and one in your actual radiator.

The sensor in the expansion tank is the coolant level sensor. The sensor in the radiator is the thermoswitch for the cooling fans, and is completely separate from the ECU and the dashboard gauge.

The ECU takes its temperature readings from a sensor mounted in the pipe junction bit fitted onto the righthand end of the cylinder head (viewed from the front. looking into the engine compartment). The same plug-in unit houses a separate sensor that drives the dashboard gauge. So it is possible for the dash gauge to show faulty readings without any effect on the engine running. The Climate Control unit gets its reading of coolant temperature from the ECU.

 

[Tartan58]

Thanks for all the info guys. So far since the day I posted the guage seems to have come back to life and has been working fine for the past week!
It's obviously not an issue that's going to cause damage to the car as far as I can tell so I reckon I'll just leave it be until it starts playing up again!

 

[tolly_tdi]

burnsy_b wrote


The ECU takes its temperature readings from a sensor mounted in the pipe junction bit fitted onto the righthand end of the cylinder head (viewed from the front. looking into the engine compartment). The same plug-in unit houses a separate sensor that drives the dashboard gauge. So it is possible for the dash gauge to show faulty readings without any effect on the engine running. The Climate Control unit gets its reading of coolant temperature from the ECU.

Hi Muttley, I have to change this and already have the replacement sensor ready but can't find where its supposed to go in. Do you have a picture/link to one so I know where to replace it.
Also how much coolant actually leaks out when you remove the sensor?

Many thanks

 

[MJ]

Its no9 in this diagram.

you might loose about a litre.

 

[tolly_tdi]

Thanks MJ! I asked Muttley cos he is pretty switched on with this engine

1 litre! omg better get a jug ready

 

[MJ]

Yep, he knows what he's on about. He would probably have posted the same pic aswell.