HELP!!! water temp gauge going from normal temp to not registering. thermostat, head

[MrTrEv]

hi guys i need some help.
my 1.8T leon's water temp gauge all of a sudden doesnt read anything then occassionally it'll read normal operating temperature (mid range on gauge) then if i take a corner it drops back down to not reading anything.
i thought it could just be the thermostat to start with but now i'm a bit worried it could be the head gasket as some colleagues and been filling my head with horror stories bout passat's HG's regularly going wrong and they have the same engine.

also there is quite a rough sounding noise that comes when i accelerate...it almost makes my car sound like a diesel and i have absolutely no idea what that can be.

need all advice possible please.
many thanks

 

[LEE69]

Chances are it's your CTS, and it's the easiest to replace.

 

[Tonybeau]

That sounds more like a faulty sensor or damaged wire somewhere but if your checking for cylinder head gasket then start off by checking your oil and water levels. If it is using either of these then they could be getting into the combustion chambers.

Check for white gunk in the oil or brown gunk in the water.

Also if you take out the spark plugs and check how they look. They should have a light brown deposit but if you run a google search for spark plug diagnostics then there are photo's of what they should look like and what they shouldn't look like.

 

[MrTrEv]

thanks for quick replies.ok thats good news not my thermometer or worse. would that explain for the rough running n unusually noisey acceleration or is that a seperate problem?
cheers

 

[LEE69]

Will affect the running as the ECU uses the same CTS for it's signal.

 

[iknownothing]

Mine's doing the same. Started off just randomly going down to the bottom for a minute or two, now it stays at the bottom and occassionly goes to the middle for a minute or two. In for an MOT on saturday and garage man said he'd take a look but wasnt ovrly worried. We'll see.

 

[Dyscontinued]

Mine used to do that for over a year, it doesn't affect anything as the temperature sender gives one outpt to the dash and another to the ECU.

It's a common fault and you need to change the temperature sender for a newer green one as opposed to the original black one.

Have a quick search, it should cost about £15 iirc.

 

[MrTrEv]

Mine's doing the same. Started off just randomly going down to the bottom for a minute or two, now it stays at the bottom and occassionly goes to the middle for a minute or two. In for an MOT on saturday and garage man said he'd take a look but wasnt ovrly worried. We'll see.

yeah no one i speak to seems to worreid bout it and general thought from guys on here and seat garage is that just a sensor but worse case scenario thermostat and neither is expensive and pretty simple to fit suposidly. i checked my oil n water and not contaminated at all so not head gasket it seems but getting dealer to plug their computer into it on wed so will let u know what happens .

 

[MrTrEv]

Mine used to do that for over a year, it doesn't affect anything as the temperature sender gives one outpt to the dash and another to the ECU.

It's a common fault and you need to change the temperature sender for a newer green one as opposed to the original black one.

Have a quick search, it should cost about £15 iirc.

did that make your engine sound rough when accelerating or just affected the gauge?

 

[Dyscontinued]

Didn't sound any different at all. Never fixed it as it was just the gauge. Was quite a popular problem for a while on here.

 

[MrTrEv]

Didn't sound any different at all. Never fixed it as it was just the gauge. Was quite a popular problem for a while on here.

mmm mine sounds like a diesel when accelerating so guess it could be another problem then lol.

 

[iknownothing]

Mine runs perfectly normally.

 

[kevsn]

Hi had the same problem with my cupra when I bought it. Took it back to garage and they changed the thermostat. Now all is well

hope that helps

 

[MrTrEv]

Hi had the same problem with my cupra when I bought it. Took it back to garage and they changed the thermostat. Now all is well

hope that helps

appreciate all knowledge passed on. i think i going to go down the route of changing sensor and thermostat as together they only £48 so not exactly major money n if that don't sort it out then its just gna be left which i hope it don't come to that as it irritates me lol.

 

[Lee_Cupra]

I've now got the same problem on my TDI so I'll change the sender first then the thermostat if that doesn't work.

can anyone tell me if it's the same drill to change these parts on a diesel as it is the petrol engine?

Also where is the best place to get VAG parts online?

 

[Lee_Cupra]

when you say CTS are you talking about the temperature sensor or the transmitter or both?