[Engine] Overheating 1.9D

[ajcommercial]

Hiya all...

  One of my 1.9D 'lingos is playing up.. The van heats up and temperature remains around 80 - 90C all day long, camper heats up to 105 then the gauge wanders between 85 -105, it goes up in temp then drops suddenly and I have found the radiator is hot at the top but stone cold below half way so I recon the rad is blocked. I have ordered a new stat and rad so I can do both at same time. Question is.. Am I right in thinking the green sender is just there for the gauge on the dash ? the fan is controlled by the ECU only so fitting a lower value stat will not make the fan come on sooner ??
 Also, I'm thinking the cooling system is very basic and there isn't anything else that can cause the radiator to feel cold at the bottom can there ?? There doesn't seem to be any coolant loss, oil loss or mix of the both cream in the expansion bottle so I'm hoping the HG hasn't failed..

  What are your thoughts ??

 P.S.. Getting a rad has been a trial, Euro Parts have been helpful but have some odd manufactures, I was going to go for the Hella at £43 but they wanted to push the EIS at £25 so I didn't buy either and bought a Valeo from somewhere else.. There are 5 different rads for the 1.9D Berlingo which is a worry !!

[polar]

You are doing the right thing AJ you need to do what you are doing before going any further or worrying anymore than you have to.

The sender should switch the fan on because it tells the ecu how hot things are. I had fans coming on when not hot and a diag said temp sender. I didnt think it could be that easy on a 2.0hdi but it was.