madsedan

The reservoir fluids is a dark black color so I'm going to drain the system and run some Prestone flushing agent with water. I figured I'll get the front up and start looking for drain plug on the radiator and I'm guessing I should pull the one on the block, any ideas where that is?

David Floyd

The block drain is under the #4 exhaust manifold, 13mm IIRC

madsedan

muchas gracias, should I drain the radiator first and then the block, and will the radiator tank on the driver's side of the engine bay drain with the radiator or will I need to idle the car with the heat on while its draining?

madsedan

The fluid in the radiator overflow tank is pretty dang dark but doesn't smell like oil, weird.

David Floyd

I don't think it will matter which one you drain first, I normally do the rad first and yes the over flow will drain with the rad

TurboTime

Messy unless you jack one side up higher than the other -for the rad.
Otherwise, it goes just about everywhere but in your bucket ;o)

hosrom_951

Don't forget to use phostphate-free coolant when you refill the system, and bleed it

madsedan

I have some of the blue BMW coolant in the garage I was planning on using (phosphate free).

J Chen

Guys,
What do you use to flush the radiator & block, I mean
is there some kind of solution that can be added before
draining the radiator for cleaning pupose ?

Peckster

Just use water to flush. That dark color is kind of weird. Maybe some misguided PO used some mechanic in a can solution to try to fix a leak. How long have you owned the car?

madsedan

I bought some Prestone flush at AutoZone, you drain the system, then drop this stuff in and fill with water. Then after you drive it about 3 hours total (over a period of a few days, not all at once) you drain everything and refill the system with correct fluid.

Peckster

And what exactly is Prestone flush removing, other than dollars from your wallet?

madsedan

Its supposed to break deposits and crap loose in the system, according to the mechanic I spoke with, he said it worked great in older cars.

J Chen

If it breaks deposit & crap, would it not clog
up the radiator ?

Peckster

I dunno man, I'd have to hear from more than one mechanic on this before I used it. My car doesn't have any deposits in it that I can see, what are they exactly?

I just replace my coolant every two years, and my system runs great. No deposits here.

Maybe your mechanic is thinking about old rusty V8 blocks or something.

I'm just skeptical because there's so much stuff out there that does nothing or is used unnecessarily.