Is it necessary to "flush" my radiator or is it OK to just drain and refil? My fluid looks fine, but it's time to change. I have a 2002 325i. Also, is the long life coolant (kind of rust colored) worth the extra money, or is plain-old prestone sufficient? I want to do what's right.
MUST use BMW coolant/ NOT Prestone. it is formulated for the aluminum radiator and your engine block. Also be sure to mix with distilled water only. Do not use the lifetime coolant stuff. It's bunk IMHO. the 'flush' part basically refers to a complete drain and refill by the way.
Coincidentally, changing my coolant is tonight's project on my E30 as well. I'm using BMW Coolant and distilled water. Apparently it is important to use non-phosphate coolant to reduce deposits. BMW brand is highly regarded ($20/gal). Likewise, distilled water ensures you're not putting other minerals into the system which is very prone to blockages (and overheating) from mineral deposits. I wonder about the "flush" question too: I would happily spend extra time ensuring the system is in top shape by "flushing" or whatever (thermostat, hoses and water pump are fine). Is there anything else beyond just the plain "drain and replace" procedure outlined in Bentley or 101 Projects that a DIYer should consider doing?
Flushing the radiator is fine but I would bet that nothing nasty will come out if the coolant has had reasonable change intervals in the past. To do a complete coolant change you will need open the block drain. On the six cylinder cars the drain is located on the passengers side under the exhaust manifolds. It can be a bear to get to on the later cars with the converters integrated into the manifolds but it is the only way to ensure all the coolant is changed. If the car has some miles, I like to flush the radiator fins to make sure no nasty stuff is choking airflow. One can either spray water backwards through the radiator with it installed (from engine side towards the front of the car) or remove the radiator for a good cleaning. Matt
Bentley makes reference to a "Cooling System Flush" in "Flushing Radiator" in Section 7, Verse 4.5. I quoteth: "For information on flushing the cooling system as part of routine maintenance, see LUBRICATION AND MAINTENANCE." I looketh there and findeth no references at all to flushing. I am currently flush with frustration. Personally, I just going drain and fill and assume now that the engine block or radiator cannot be "flushed" in any way. Erich49: Sorry for accidentally hijacking your original post; hopefully the posts on the topic have been helpful for you too. Sometimes I try too hard to make easy things complicated; it should be easy; just use the right products.
