Have checked wiki/search forum and can not see any refrence to this so appologies if i missed it somewher but i am new

Ok so 1600 td ran perfectly ,was of road for 6 months and hey presto it now runs much hotter than before abouth 3/4 on the gauge and engine has developed that hot oil smell.
No loss of coolant no evidence of leaks and waterpump replaced and thermostat checked.system flushed and rad flush treatment added to system.engine flushed and new coolant.....
No change.
other symptoms ....Switch heater matrix on and engine temp drops.
Conclusion clogged up radiatpr matrix from being layed up for 6 months???
If so and i can really think of nowt else what is the best way to clean and flush it?
anyone else experienced this?