High engine temp under load

[Rumcajs]

Argh, the suggestions.
Example, does it start to overheat when climbing a hill but recovers quite quickly on flat, downhill run? Under load temp increase could be related to reduce coolant flow through radiator means the radiator is getting blocked either externally (easy to see) or internally ( impossible to check unless dismantled.) Externally blocked radiator can also affect viscous fan thermostatic valve which doesn't get any/reduced hot airflow over it hence it is not engaging when it should. In either case the cooling system is becoming marginal and can't keep up when ambient temperatures or load increases.
The best way to check externally blocked radiator is (if you can there might not be enough space between fan, shroud etc.) is to stick workshop omnidirectional inspection light behind the fins and check from the front how much light is visible. (you can also see the filth stuck among fins).

If the silicon fluid from viscous coupling leaks out it leaves the tell tale traces of dust spots (the oil really attracts dust) near where it leaks. Another option is to check (this is general info might not apply to TD42) when engine is cold (first start) the engine fan should be heard roaring when RPMs are increased and if after hot run the engine is turned off and fan is engaged it will stop with the engine immediately when engine is turned off. If it keeps spinning than it is low on fluid and while still hot it should feel reasonably tight to turn.



Cheers