Did you replace it with a used radiator or a new radiator? What temp does it usualy run. With a perfect cooling system it should stay at about 80C regardless of conditions or load.

Could be the head gasket as well, lots more info is needed.

Have you pressure tested the cooling system?

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200