When to change Coolant Reservoir hoses (Upper/Lower)

[Bls72bmw]

Team, Wondering when is it time to change out the Coolant Reservoir hoses?
I'm doing a water pump/upper-lower Rad hose/thermostat on a 2000 323Ci w. 160k. Not sure if the water pump has ever been done, (how do I tell?)

Looking at the hoses to the Reservoir tank, they 'look' OK, but wondering if they are much of a problem?

Thanks!

[fumigator]

If you made 160k and it hasn't been do it all. Water pump. Radiator. Tank. Hoses. Tstat. Otherwise the undone is the weak point and only a short time away.

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[jclausen]

The bigger question is how old the plastic expansion tank, they are black when new then turn tan color when worn out and cracking. If it's old replace that along with the plastic mounting plate and then it's and pices thath go along with that. Might check th plastic pipes that run under the intake manifold, behind the oil filter stand

[Bls72bmw]

Expansion tank IS being changed- since it blew a leak- so that's the reason to do all this.

I CAN'T SEEM TO FIND A TUTORIAL ON REPLACING THE HUGE LONG HOSE THAT GOES FROM THE EXPANSION TANK ALL THE WAY BACK TO THE FIRE WALL....ANYONE KNOW WHERE I CAN FIND IT PLEASE? That hose is BURIED....dang, looks like a big job. I have the hose, but it has me wondering how far I have to disassemble and how long that hose lasts, and what the failure rate is on it?
Thanks Team.

[MarcoZandrini]

The consensus here and on other bimmer forums is that the cooling system needs to be overhauled at 100k miles/163k kms. That includes:
- water pump (Saleri or Graf)
- thermostat (Whaler)
- hoses (Conti, formerly known as Continental)
- expansion tank (Modine AND ONLY MODINE)
- expansion tank cap (I ran a 1.4 bar (~19psi cap from an E30)
- expansion tank bracket
- temperature sensor in the lower hose
- serpentine belt (Conti)
- idler and tensioner pulleys (INA)
- radiator (Nissens or Behr)
- 1 gallon of BMW coolant (and ONLY BMW COOLANT)
- 4 gallons of distilled water
- block cooling drain plug crush washer

Go to www.realoem.com and enter the last 7 characters of the car’s VIN. Hit enter and bookmark the page. Cooling system parts are located in the engine section and in the radiator section. With the part numbers in hand go to FCPEuro to buy the parts. For every part number FCPEuro will typically show 4 parts.
- BMW branded ($$$$)
- original equipment ($$$; made by the supplier of this part to BMW)
- original equipment manufacturer ($$; made by a supplier of parts (but not this part) to BMW)
- aftermarket ($)

Buy only original equipment parts (noted by brand). The installation of aftermarket cooling system parts is strictly verboten.

Now, those plastic pipes, one of which runs under the intake manifold (WTF BMW) is the question of the moment. What are your plans for the car? If you plan on keeping the car for another 50k miles then you really need to consider replacing those 2 plastic cooling pipes. What is your level of expertise when it comes to wrenching on your car? The replacement of the pipe under the intake manifold is not technically hard but it does require attention to detail, lots of photos and time. Also, one end of the pipe under the intake manifold plugs into the cylinder head. That can mean corrosion in the aluminum cylinder head. There are a couple of threads on this forum that cover the process. It takes patience.

[jclausen]

The long hose goes back to the heater I think, I would say it's not a big job or complicated, I did my plastic pipes as soon as I got my car that was a bit of a hassle

[MarcoZandrini]

j, thanks. I missed that long hose question. OP, those hoses are typically not changed at the 100k mile overhaul. Why? I don’t think that they’re under a lot of pressure. j, can you confirm or correct my last statement.

[Bls72bmw]

Great Great info. Yes, I mean the heater hose that goes way back under the car.
I changed the lower one easily, and since it seems to be not a high failure part...it's gonna stay!
Great info guys, this car is a local DD and not a track or cross country car. I have see the tutorials about changing the plastic pipes way under there by the block, gonnna wait on those too. BUT def doing the other main stuff.

I'm in Minnesota, is 1 gallon of BMW BLUE mixed with distilled enough freeze protection?
Def plan on going with OEM Blue coolant.

[MarcoZandrini]

Yes, that mixture is fine in Minnesota.