System flush

[Theantony]

I’m changing my thermostat so presume I’ll have to do a full system flush and bleed. I’m going to use xtreme g48
coolent from what I’ve read. How much will I need for a full flush.

[jps635]

The system takes 12l.

I did an expensive engine rebuild last year and after reading all sorts of stuff I used BMW coolant @ 40% strength mixed with tap water.

[Da_Hose]

A flush is not complicated. You can get chemicals to help, but I have always done a simple water flush. If there is anything actually gumming up the radiator, it will need to come out and get boiled/rodded (if it's an older brass unit), or replaced.

I would suggest buying an in-line drain for your lowest line. Drain at the block, fill with plain old tap water, leave the radiator cap off, run to operating temp with heater on, then drain at the tap slowly, while adding water in the overflow. The system holds 2-3 gallons if I recall correctly, so once you have allowed a gallon to drain slowly, stop the engine and drain the whole system, including at the plug once it has cooled. You can pull the in-line drain if you want, but I'd leave it in.

Refill as usual with a pre-mix coolant. There are only 3 or so places in the world that make the glycol used for engine coolant, so I honestly don't think there is a ton of difference from brand to brand. The key is to get coolant that is meant to work for your car, as additives and properties are incompatible between some coolants. Long life coolants are most finicky, because they can be organic acid coolants (OAT), or nitrited organic acid technology (NOAT) coolants. If you mix those two types, you can end up with funky colors or sludge.

I went with Evans waterless coolant, because it prevents corrosion, and there's no huge pressure increase when hot. If you do heat up, the outcome is less disastrous than when you have water in the system as well. The Evans route is more expensive, but I think it's worth it.

Jose

[Theantony]

Thanks guys

[86_6series]

Owned my six for 31 years. Never used BMW anti freeze. Zerox or Prestone with

https://books.google.com/books?id=wC0DA ... st&f=false

I remember reading about the water in Europe years ago and used regular distilled water when mixing.

Never had a heating problem with the engine in all these years. Orig rad and heater core.

https://www.germanautocenter.com/blog/w ... utomobile/

Just FYI