I have to put a new radiator into my 300D (603 engine, non turbo) and I have consulted my Haynes Manual which, surprise surprise, gives me most of the information, but not all !

So here goes, Haynes says drain the system, by naturally undoing the coolant hoses but also by undoing the engine block drain plug...question, where is it and is it necessary?

Next stupid question: Thermostat: is it located where the top radiator hose goes into the housing to the right of the cylinder head...held on by 2 bolts?....I only ask as it looks much smaller than the thermostat housing on my old E280 which was very obviously the thermostat housing

Other than that it all looks pretty straight forward, however, are there any tips that can be given.

Thanks and sorry for being so dumb

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Current Mercs
R129 1994 300-24SL
W124 320E Turbo Technics Twin Turbo 350bhp

Previous Mercs
W124 1986 Quad Cam AMG Hammer, 45,000 miles
W124 300E Turbo Technics Twin Turbo 320bhp
W124 E500

On a US car the thermostat is at the top of the bottom hose. When I drained my coolent I just pulled off the lower hose, I was changing all of the hoses anyway. Then I flushed it out with a garden hose.

Only use Mercedes coolent in a 603!

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200