hello ive got the 2.0 urbo diesel townace on the moterway after about 55 miles it starts to climb the guage when this happens the heaters blow cold air when i stop its usualy lost no more than a cup of water .the strange thing is i can run all day in standing traffic or arround town and this dosent happen can anyone help .i ve changed the thermostat there is no change.ive also had a pressure test on it from the filler cap this was normal.could this be a blokage in the radiator or would i benefit from changing the cap or could it be the dreded head gasket i dont know if anyone does please reply paul

- (#3064) paul, 22 May 02

To give you the most in depth view of any potential problems I must direct you to the archives of these pages, a link shown above.

To give you a rough guide of possibilities beginning with most likely


Viscous fan coupling
Can be tested by driving along the motorway at the speed you mention with the engine cover up and seeing if the fan stops. Another method is to attach thread to the fan blades and tying off on bodywork. start the engine. If thread does not break then remove thread and get engine up to temperature. Connect thread again with engine at temperature, the thread should now break as the coupling locks in place.

Radiator cap
A very important item of the cooling system, much overlooked. It is possible that the spring tension could be weakening, main seal not sealing and not putting system under pressure. A pressured cooling system increases the boiling point of the coolant. If your radiator cap is not putting system under pressure then this could result in areas of your engine boiling thus forcing steam out of the system.

If you are going to change the radiator cap then the new type that David found has been given the green light, ADL Blueprint also recommend it for our engines. The part number is ADC49902 and prices differ from £7.50 to £17.00.

My system actually didn't show any of the above as being faulty but the garage is now saying that the viscous coupling, although turning, is not drawing the air flow through it so be aware of the fan not necessarily stopping but slowing down. There should be a roar as the coupling locks up and runs virtually in speed with the engine.

Much more information available from the archives.

- (#3076) Mark, 23 May 02