Temp issues

[dannydubs]

Got a 1.8 driver having a little issue with temp car runs fine,fans working fine
Car is Geting up to temp and sitting over half way
Sitting at around 100-110 but doesn't go higher or over heat
I've read some where if it sits below middle it's one thing or sits over middle it's another
Thing just can't remember which or what
I'm guessing either temp sensor or themostat?

Any one help?

[Seanl]

Could be either, but more likely to be temp sensor. Change that out first, but if no luck go for the stat. Usually the stats stick open, but if yours is not fully closed and stuck there, it will only be allowing a small amount of coolant to circulate, thus running at a higher temp. Thermostat is cheaper, but will take far longer, and be far more a pain in the arse to change. Temp sensor will take 2 minutes to do. 

[Rmachines]

Yea sounds like the stat is stuck half way, its cooling the engine sufficently to prevent overheat but not enough to keep it at 90c.  But a new temp sensor will never hurt on a MK3. lol

[dannydubs]

Dnt think it's the sensor and thermostat is opening
As bottom hose is Geting hot

[Rmachines]

The bottom will get hot, as the stat will be opening, which will balance the rad with the rest of the system but its not letting enough through to fully cool it,    To be totally honnest, theres not much else it can be, its a simple system on these, so either its too hot due to the stat or its fine and the sensor is telling porkies.   I have never seen a sensor over read to the gauges though, my money is on the stat.

[dannydubs]

Just had another look gets to just under 110 then fan kicks in drops back down to
100 ish then back up 110 again then fan again just keeps doing this cycle but
Doesn't over heat no warning lights

All mk3,s I've had just sat in middle and never moved

[Rmachines]

Actually, thinking about it, its going to be the temp sensor, as the fan switch will kick at just above 90, if it was the stat causing it to run higher, then fan would always be on untill it reaches half way,  so if the fan kicks when it over half way, and goes off before its exactly half way, it can only be the temp sensor givin the wrong signal,   Unlikely to be the stat, and a lazy fan switch.

[javalin]

I thought the radiator fan switch kicked in at > 100c?  Thus I'd have said the CTS was OK and its a stuck T-stat or a blocked rad, etc.

Have you tried bleeding it?  Not likely but might be worth a go.

James

[Rmachines]

Im not to sure when the fan kicks in but i do know the gauge doesnt move from half way before it kicks in, so theres not much in it.

[javalin]

well it will be over 90c for sure, I am fairly sure its 105c or so, i.e. it shouldn't kick in during normal operation.