E36 Radiator Flush
Flush your Radiator
This is the way that I flush my cooling system, you might find an easier way to do it. Some people don’t drain the block twice. I only do this to get an accurate mix of coolant and to get the tap water out of the block. This is a very messy procedure, I’d suggest doing it in the street by a drain or better yet, in your neighbor’s driveway. I also would’t do this in your garage unless you can hose it down or you live in the ghetto and you’re renting, like me. Anyway, I had this done at the stealer and they charged me $82.00 but as part of a package deal–You can do it here for less than $30 bucks. Read on, brutha.
Why: Antifreeze breaks down in time and becomes corrosive, which will eventually cause bad things to happen to your engine. The Bentley manual sez flush it every 36 months, but I do it every 24 months just to be safe.
Cost: If you get the parts mail order, it’d probably cost around $20. Like I said above, $82 from the stealer (I’ve heard up to $200!), considerably less if you do it yourself.
Time: Took me about 45 minutes, 25 for the actual work, the rest to clean up and hose off the driveway and to feed the extra coolant to my neighbor’s cat. Just kiddin’ no flames and no SPCA please…in fact, donate to the Society for the Prevention of Cruelty to Animals they’re a worthy organization. Whew. Off tha hook.
Skill level: If you can change your oil, you’re doing well. If you can read, you’re also off to a good start.
Here’s an exploded shot of the radiator, from the official parts CD. Revel in it’s greatness.
This is the radiator drain plug located at the bottom of the driver’s side (left side if you’re in the car) of the radiator. If you jack up the car, lay underneath it and look towards the front of the car, this is what you should see, although some of the drain plugs are black. Use a large flat bladed screwdriver to loosen the plug, or you can use an 8mm socket–it’s really easier to use a screwdriver, but do whatever the hell you want–it’s your car. Put a hose up to the drain plug and remove the plug so the fluid flows into the hose. Make sure something else is on the other end of the hose to catch the fluid besides your neighbor’s bushes…oops…
This view is looking down where the airbox should be (I have a Dinan cold air intake so the box is gone). See? The hose is on the drain. Use a shorter length of hose, mine was too long and the fluid backed up and spilled everywhere. Oh well, so much for being neat.
While the fluid is pouring out, open up the radiator fill cap and unscrew the vent plug (the blue arrow) with the same flat bladed screwdriver. This will help to turn the uncontrollable dribble coming out of the drain into a gushing mess.
Climb back underneath the car and locate the engine block drain plug. This is on the passenger side of the engine, hidden underneath the exhaust manifold (as seen in the foreground in the picture). You can’t see this from the engine bay, so don’t waste your time looking. Trust me. Anyway, use whatever you can to open it (I used an open ended wrench–it’s either 19mm or 13mm–I’ve heard both). WORD OF CAUTION–lay as far back as you can and just ‘feel’ your way to that plug ‘cuz when you undo it, fluid will splash EVERYWHERE since the headers are blocking the direct path to the ground.
See? I told you. Note the drain plug on the ground. Note the bucket under where the coolant should have been. Note the half gallon of coolant all over the ground. It was at this point that I found out that coolant really does taste sweet! Mmmmm! Now I know why cats like it. Weird. ANOTHER WORD OF CAUTION: ethylene glycol is not a food product; please do not eat or chew!!! After the coolant is done spiling out everywhere, put the plug back in. You can get a replacement crush washer for the plug if ya want, it’s probably better that you do but don’t put it on yet! Don’t tighten it up too tight, cuz in my procedure it’s going to be removed again!. In retrospect, maybe if you put a big ass funnel up to the drain plug it wouldn’t be as messy. Oh well.
Put a hose in the radiator and turn it on. This will kinda clean out the radiator. Next, turn on your car and turn the heater on to full blast. This will help to get the thermostat inside the engine to open up and start circulating the water from the radiator though the engine. Run this for about five minutes, or until the water comes out clear. Or go crazy and do both! Your cooling system is now flushed.
To finish it off, undo the engine drain plug again, spilling water everywhere. This is to get the water out of the cooling system so you can get an accurate mix of coolant, also because you don’t want to use anything but distilled h2o in the cooling system–tap water will help to corrode everything.. PUT BOTH OF THE PLUGS BACK IN! Put the crush washer on the engine drain plug, and tighten to 18ft-lbs and the radiator plug to just-tight-enough so fluid doesn’t leak out–Bentley says 18-27in-lbs–not ft-lbs. With no water in the cooling system, you can pour in one gallon of BMW coolant first, and then one gallon of water for a good mix (if you have zero math skills, that’s 50-50–that’s what one of the BMW mechanics was using) or you can adjust to taste. Turn the car on with the heater at full blast to circulate the coolant and to get all of the air out. Put the fill cap back on but not the vent plug. Coolant will bubble out of here when the air escapes so wait a few minutes until the fluid comes out bubble free and then put the plug back in. Turn your car off and then clean up. In the next couple of days, look for coolant leaks (check the drain plugs) or if the temperature is too high (past middle–might be air in the hoses, open up the vent plug again, but I doubt it).
Oh yeah, I should probably tell you that dumping or throwing out coolant can get The Man on your case. Find a place that takes coolant (local garage?) and dispose of it there.