110 overheating on motorway?

Hi everyone. I have a 110 with a 300tdi engine, driving at low speeds around town etc the temp gauge sits half way perfect and always has done. Took it on it's first long motorway journey today and it overheated after minutes so pulled over, cleaned some mud from the radiator with a jetwash and carried on, was fine for about 20miles But then temp slowly went into the red again. We had to keep stopping and each time it would cool then be fine for a short while (5ish miles) then would slowly creep up again. Once off the motorway and back in town the temp dropped to normal straight away. Oil and coolant levels are ok and no obvious signs of them mixing or head gasket failure. Any common faults with this?? Thanks alot, Craig.

Check for even temperature over the rad and top and bottom hoses........could be a partially opening thermostat or blocked rad.

radiator is most common fault check core by feel should be hot all over if it isnt it needs replacing ,if top hose cold replace thermostat ,fill system and check system with the two plugs removed 21mm socket fill till over flowing even header tank ,excess will come out to correct level harmlessly ,level in header tank isnt indicator of engine level,buy new plugs brass preferably before removing old ones ,as should be done regulary

Thanks guys. Should I check the rad core when the temp is in the red or when at normal operating temperature?

both

Will check next time I can give it a run. Thanks alot

as soon as engine at running temp is enough

First question - are you losing any water?

The temp sitting in the middle seems a little high to me - well based on my 300Tdi 110, since I replaced the water-pump gasket (rise in temps and loss of water) it never goes above ~1/3 of the way up the gauge. Standard radiators etc.

It doesn't seem to, certainly not losing a massive amount if it is. I will try and get a pressure tester on it when I check the rad. Just waiting to get access to it as it's in a lock up at the minute. I'll let you know of I find anything when I look at it

insufficient flow through rad, money is on a blocked rad or lack of fins, could be water pump impellar shot, enough circulation at low revs but insufficient when running at speed hence the constant increase in temp

cheers steve

Thanks Steve, that's another thing to consider. To be honest I am thinking radiator, it makes sense. I'll get it hot and check it, if the rads not the problem I'll have to look deeper and poss at water pump. Thanks for all the help fellas