Temp gauge drops while driving

[vw754]

Heaters are warm-hot.......not very hot,ive tried bleeding the coolant system.....after a replacement of cambelt kit + waterpump.....the temp gauge takes a very long time to reach 90c .....even after a good 5 mile run it just about makes it to halfway.......then if i drive and put on the heaters,the temp gauge keeps dropping..........i know this is not normal......the temp gauge in vcds reads above 83c...any ideas? 51 plate 1.9 tdi ATD engine.

 

[s3 Hoggy]

Have.... You.... Replaced.... The.... Thermostat?.....

My S3 used to do that turned out it was the thermostat

 

[S3featesV9]

Had same thing on my car not too long ago, and it was thermostat bud. It'll be stuck open.

 

[<tuffty/>]

Replace the CTS too... someone I know had similar symptoms on his TDi Golf... turned out to be the CTS...

Just remember that VCDS will only show what the ECU thinks the CTS is telling it... Check the temp reading for the dashboard in vcds too... can't remember the module/blocks off hand but the CTS contains two sensors, one for the ECU and one for the dash... compare the readings as typically when a CTS is on its way out it one will be lower than the other...

<tuffty/>

 

[rich4130]

Another vote for thermostat, worth changing anyway IMO two I have done have bits of water pump impeller in!

 

[egesford]

thermostat.......................

 

[vw754]

Have.... You.... Replaced.... The.... Thermostat?.....

My S3 used to do that turned out it was the thermostat

not replaced it,where is it located,,,and is it an easy job?

 

[vw754]

Replace the CTS too... someone I know had similar symptoms on his TDi Golf... turned out to be the CTS...

Just remember that VCDS will only show what the ECU thinks the CTS is telling it... Check the temp reading for the dashboard in vcds too... can't remember the module/blocks off hand but the CTS contains two sensors, one for the ECU and one for the dash... compare the readings as typically when a CTS is on its way out it one will be lower than the other...

<tuffty/>

good to know.....will have to find out which measuring blocks it will state cts readings........il replace the thermo anyway.

 

[egesford]

thermostat is an easy job, just need a socket set and a screwdriver and about 20 mins. careful where you get it from though, i got one from ebay and it came with the wrong o-ring

 

[fingermouse]

Get either a OEM one or the best GSF / Euro do , I wouldn`t buy a hoo song wang one.

 

[egesford]

no definitely get genuine, i got cheap one off ebay, a week later i had to change it

 

[vw754]

Get either a OEM one or the best GSF / Euro do , I wouldn`t buy a hoo song wang one.

lol........genuine.....or good make defo.