Bleed system...Yeah right... Need Some Help Here Please

[frecon931]

89 325i, has never overheated but gets hot!!!
Replaced: Water Pump, Lower Temp TStat, Timing Belt, Tensioner, Coolant temp sensor low temp, Radiator, Coolant w/water wetter, Took out old fan w/clutch and replaced it with spal fan 1300 rpm electric fan. I've bled the system several times, had the head gasket checked and is good, Car Only has 67,000 orig miles, When I drive the car it will heat up and as long as I turn the heat on full blast the temp will stay around the half mark or slightly above, if i turn the heat off it will heat up and once it gets close to the red... the heat will start to go cold and I shut off the car. The car does not run rough or sluggish in any way when it heats up? Also the lower temp coolant sensor never kicks the aux fan even though I can hit the A/C button and it comes on right away??????Please someone help me with this Thanx in advance Cory in South Bend, Indiana

[thejlevie]

Sounds like you have air in the cooling system. The bleed procedure I use is below.

As an FYI, I think you'll find that the 1300cfm fan is going to be less than adequate in summer weather. I found that it required a 16" fan rated for at least 2000cfm.

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500 for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

[lordofthewaters]

I also squeeze the hoses (with a towel) during this process, as air can collect in the top hose particularly.

[1988 325ix]

Same problem with my '88 "ix". I had to bleed the system for like 15 minutes if not longer to get all the air out and like the person before aid make sure you squeeze the hoses, they're above the bleed screw so air WILL get traped up there and it has to be pushed out by hand, if you don't do that it will just cavitate up there. Just keep bleeding it even if you think it's good because there will still be air in the system.