Engine Operating tempurature Flucuation Issue
 

For awhile now my 300TD has not been able to maintain a stable operating tempurature. in traffic it will hover just above the 90 degree C mark. at highway speeds it stays stable at the 80 degree C mark or just above it depending on the ambient tempurature outside. But, if i get on it to pass a truck or go up any sort of grade the tempurature starts to climb and will stabilize around the 90 degree mark if it is cold outside.

Just this weekend i was in a caravan of vehicles moving slowly along some steep wind-y roads. for the first port of the accent we were moving at a good 35 miles an hour but the temp just kept climbing moving up to the 120 degree mark. with the heater on full blast i was able to stabilize the temp before reaching 120. but i could not get it to drop untill i reached my destination and shut off the engine.

so to get to my question, is this a coolant flow or airflow problem. I have more evidnence to support the former as the fan clutch does engage fully and engages at the correct tempurature.

where do i go from here??

Disclaimer: For those of you who have read my thread about burning used motor oil in my engine, this is an unrelated problem and it has been going for quite awhile.

Check that the air flow through the radiator is not blocked with debris.
If not, replace the radiator.

I did clear a couple of leafs out, but there wasn't enough blockage to affect the flow enough to cause that sort of behavior.

as for a new radiator, my father and i have only used Behr radiators in all of our cars. however the only one fastlane shows for the 603 engine is made by nissin. any change in quality there???