Mr
You changed the radiator, and the thermostat, correct? Please describe your procedure to refill the coolant.
When the engine is running, feel the top hose and bottom hose. Describe the temperature you feel. Squeeze the hoses - are they soft, or firm? You need to get more information.
p.s. Don't burn yourself or cut your fingers off in the running fan, and don't get your hair or clothing tangled in the serpentine belt.




On my diesel the pump had originally plastic impeller, who broke on halves at some point. After thermostat removal I was able to stick my finger into the hole and feel broken impeller.




When radiator inlet is much cooler - that is indication of lack of flow, what again can be closed thermostat as well.
Than compare radiator inlet and outlet temperatures.
Bear in mind infra-red will give you different readings when you point it to different materials of the same temperature, so play with it a bit before making final conclusion.
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Not knowing if you are in US or not - if you had a leaking radiator/so you replaced that - and you still had a overheat/red-zone-temp-gauge and you replaced the thermostat with the correct one - if it was me I would suspect a main fan problem. and/or a auxiliary/electric fan problem maybe too.
Do a google - the main W210 engine driven fan has a internal sealed "hydrostatic clutch" - and with time/miles that engine fan can fail - where the clutch only "softly" locks the blades (rather than "firmly") so with that failed/failing clutch main fan spins/makes-noise - but really doesn't move much air at all thru the engine compartment.
Do NOT cut your fingers off - do a google on how best to diagnose that FAN
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I will get back to the machine for further diagnosis..





