overheating on long journeys

[theemike]

hey got a 90 200tdi that overheats but only when travelling over 45mph for sort 15 miles had new head gasket and stuff but not helped??

[ChrisV8]

Whats the rad like ? Could well be not cooling enough, blocked with mud or no fins ?

[theemike]

was told by another person the rad cores might be blocked?? is that inside rad?

[ChrisV8]

Yep the vertical cooling tubes are mighty small and can get blocked with muck and sludge out of the cooling system if it hasn;t had reasonably regular changes of fluids.

You could try to flush it out by backflushing with a hose etc but it may be best to bite the bullet and get a new rad. Haave you pressure tested the rad etc ? It may be that the cap is not sealing properly do you have to top up the water after a trip ?

[frosty]

  has the 200tdi got the same fan set up as the 2,5td..in that its a viscous coupling? if so it could be that thats faulty

[ChrisV8]

I have leccy fans on both my tdi's and rarely need to use the fan so unlikely that a failed vicous unit will cause an overheating issue in my opinion only and under cooling one and increased fuel consumption.

[frosty]

 my 2.5t does the same thing..changing the viscous coupling has improved the heating problem but i dont think its cured it... looks like ill be flushing the radiator out next!