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DISCUSSION => General Topics => Topic started by: johnwoo on September 18, 2008, 08:46:33 PM

Title: Best way to properly bleed cooling system
Post by: johnwoo on September 18, 2008, 08:46:33 PM

ok guys with the help of my bently and the diy on this site i changed the fan clutch, thermostat, and water pump.  now i am refilling the coolant in my system.  what is the best way to do it.  i've read some different ways.  some say to take the bleed screw out while others say just unscrew it a couple of times.  
i started the engine and filled it with coolant and have my heater blowing hot air now.  when i unscrewed the bleeder valve coolant is still not overflowing, so what do i do? how do i get it to overflow?  the coolant isn't even coming out of the bleeder screw
and just to get my bearings straight the bleeder screw is the plastic screw that says "entluftung" right?

also where did you guys fill the coolant to?  the cold line or past it?  im about two inches past the fill line.  do i need to remove the excess coolant or can i get the excess out through bleeding it.  let me know what the best way is.  im sorry if this post sounds retarded im just confused on how to do everything.

thanks for you guys help.

Title: Best way to properly bleed cooling system
Post by: KenC on September 18, 2008, 09:12:13 PM

Is the return line on the radiator really hot when you're starting to bleed it?  Make sure it is.  Drive the car around for 4-5 minutes.  Your heater can be blowing hot air with the thermostat closed.

You should have the bleeder screw off when you're actually filling it.

Elevate the front of the car when you do it as well.

Title: Best way to properly bleed cooling system
Post by: johnwoo on September 18, 2008, 09:50:09 PM

ok so let the car run with the bleeder screw off?  the coolant level is alredy higher than the mark.  what do i do now?  just let it run until it gets hot and the bleeder hole will overflow with coolant? and i have the car elevated.

thanks for your help.

Title: Best way to properly bleed cooling system
Post by: johnwoo on September 18, 2008, 10:07:02 PM

also is the bleeder screw the screw that says "entluftung"

Title: Best way to properly bleed cooling system
Post by: monty23psk on September 18, 2008, 10:15:58 PM

http://www.esatclear.ie/~bpurcell/318ismaintenance.html#bleed (http://www.esatclear.ie/~bpurcell/318ismaintenance.html#bleed)

Title: Best way to properly bleed cooling system
Post by: johnwoo on September 19, 2008, 12:15:03 AM

yeh i have that site bookmarked but he says to only unscrew it some say take the bleeder screw off so which one?  also is the bleeder screw the plastic screw that says "entluftung"?, so i wait until fluid is spilling out of that area?

Title: Best way to properly bleed cooling system
Post by: johnwoo on September 19, 2008, 12:19:54 AM

better yet i took a pic.

(http://i37.tinypic.com/1ioq4x.jpg)



^^^ is that the bleeder screw ^^^

Title: Best way to properly bleed cooling system
Post by: johnwoo on September 19, 2008, 12:22:34 AM

if it is i guess i just run the car with the bleeder screw cap off until the coolant overflows from that hole?
also is it ok if i overfilled my reservoir a little bit i figured the excess will flow out of the bleeder screw.  am i correct?

Title: Best way to properly bleed cooling system
Post by: KenC on September 19, 2008, 01:37:21 AM

1 Let the car completely cool down.
2 Loosen the bleeder valve (the little round on in the picture). Note the level of the coolant in the reservoir.  You want it right at the cold level.  Take some out if it's above, add if it's below.  Retighten the bleeder valve and put the radiator cap back on.
3 Turn the car on and turn the temp and blowers on high (you want to get the coolant going through the heater core).
4 Drive it around for a few minutes and really heat it up.
5 Make sure the coolant return line (the one on the left of the radiator if you're looking at the car) is completely heated up.  You will know then that your thermostat is open.  It is possible to still blow hot air and have the bleeder valve shoot coolant with the thermostat closed.  It is IMPERATIVE that the car is completely heated up and coolant is flowing through the block all the way through the radiator.  When the return hose is hot, you know you're heated up all the way.
6 Park the car on an incline or elevate the front end.
7 Slowly unscrew the bleeder valve.  You will most likely hear a hiss of air followed by a squirt of coolant.  Tighten it back up and you're done.

Title: Best way to properly bleed cooling system
Post by: johnwoo on September 19, 2008, 01:44:39 AM

great so step 7 i just unscrew? don't actually take it off?  thanks for all of your help.  

so i got the bleeder screw right?  its the one i arrowed?

Title: Best way to properly bleed cooling system
Post by: el_gringo on September 19, 2008, 09:18:27 AM

yes

Title: Best way to properly bleed cooling system
Post by: TomO2UT on June 23, 2009, 11:02:25 AM

Ken: Nice summary; just to clarify, is the engine shut off during step 7?

Title: Best way to properly bleed cooling system
Post by: DesktopDave on June 23, 2009, 11:38:51 AM

This isn't BMW specific, so YMMV, but here's my technique:
1. I fill the top coolant hose until I can't get any more coolant in...make sure the heater is set to full hot too.
2. After reconnecting that, I fill the overflow tank to the normal cold mark.
3. Then I just point the nose of the car up my steep driveway and turn the car on.
4. I put the heater on high, open a bleeder (or whatever pressurized connection is highest) until the bubbling stops, make sure the hoses & cabin both get hot and then close off the bleeder or button up the system...
5. I take the extra coolant in a jug, set off on a drive and verify that it's still full.
6. I also check the level monthly, just for kicks.  This car seems more sensitive to coolant system problems, IMHO.

Title: Best way to properly bleed cooling system
Post by: B318M42W on June 23, 2009, 11:52:45 AM

if you don't want to drive around, i read (and tested...) that if you rev the engine above 4500 RPM there will be a coolant circulation. it's easier to do if you have a buddy take care of the rpm. but yeah, basicly just fill to the cold line and then start her up and as the reservoir empties, add some more. when it won't take anymore, time to rev. hope this helps

Title: Best way to properly bleed cooling system
Post by: Balkanac on January 14, 2010, 10:11:43 PM

sorry about digging up and old thread but i had to change the thermo in my car today and i just wanna say that this thread helped a lot. Thanks everyone