200Tdi bottom hose stays cold

[DrRob]

As title says, bottom hose and tank coolant stay ambient temperature - not even warm to touch after a run; top hose gets hot; temp guage shows normal.

Only work carried out recently is new cambelt kit and new coolant...

Has got a 2year old new rad and a <12month new viscous fan coupling.

Any thoughts? Normal?

Thermostat or water pump? Both?

Air lock?

Any "procedure" I can follow to isolate problem?

[Les Henson]

200 and 300TDi engines are overcooled, so at this time of the year I wouldn't be surprised if the bottom hose was cold for an hour or so - especially if the vehicle is moving during that period. I know of these engines having no fan at all for most of the year as they are generally not needed (an electric fan conversion almost never comes on).

Les.

[DrRob]

Cheers Les!I'll keep an eye on it etc.

I just thought it was a but strange but I guess it makes sense as my rad is new and I keep it clear of any mud etc.

I just don't want to "hurt" it for the sake of a thermostat etc.

[Riz Sauvage]

You wouldn't hurt it, if the thermostat was locked shut, it would over boil, if it was locked open, it just wouldn't heat up that quickly, no damage on that one.

[Range Rover Blues]

No if the thermostat was stuck open (most common) it would take longer to heat up and perhaps always run cold, this leads to higher fuel consumption and premature wear as well as cold passengers.

If the top hose is hot and the bottom hose cold then all is well I'd say.