Did a full service on my '03 BMW 530i today. It's Christmas, the shops kind of slow, so I said screw it and brought my own car in.
The only part of the cooling system not replaced was the radiator. The car has 127k miles on it, and it looks like the PO replaced the radiator, reservoir, and fan clutch. Not sure howwhy those 3, but the rest was original. So, it got:
Upper & lower hoses, and fan switch in the lower hose
Fan blade & clutch
Reservoir, cap, coolant level sensor, brass bleeder screw
Both hoses off the bottom of the reservoir (one goes to the aux water pump, 1 goes to another hose that goes to the heater core (replaced that one as well)
And the 4th small hose that goes from the aux water pump to the heater pipe that runs under the intake.
Water pump
Thermostat assembly
While I was there, I also went ahead and did the belt tensioner and the idler pulley, and a new belt. One of the pulleys was squeeking like I had a supercharger, so I just took care of them. And also did the oil filter housing gasket. It's been leaking pretty good. It was rock solid, of course. Oh, and I replaced the power steering reservoir, and both lines that go to it. The other cooler line to the rack looked perfectly dry, so I figured I'd wait on that one, and pressure lines are expensive and always look like they leak - so, no reason to even touch it, imo.
The cooling system was filled with something yellow, probably Prestone or some such [censored]. I did a number of drain/fills (fill it, run it for a bit, let it filter it thru, then dump) until what I saw in the reservoir while it was running and what came out of the radiator drain was clear as day. Topped off with a gallon of BMW Blue, and all is good for a couple years until it needs to be drained/filled again.
