Filling and bleeding coolant DIY (BMW E46 generic) doityourself

[billschusteriv]

You should fill coolant before starting the car or running the car for an extended period of time (where the car temperature gage indicates the temperature has risen to normal operating).

If the car has been running and is at normal operating temperature, turn off the car and let the car cool for a few hours.

Open the hood and locate the coolant fill cap near the front of the engine compartment.

Slowly remove the fill cap.

There is a float that should provide indication of your level. An attached indicating plate tells you how to read the float (see pictures below).

If needed, you have a screwdriver in your toolkit in the trunk. Use the phillips end to open the bleed screw near the fill cap. Just a few turns should be necessary to create a path for the air to escape.

Slowly commence filling the system with the appropriate mix and type of coolant*. Do not overfill. Remaining air should leave through the path created by the bleed screw.

*Note: BMW Coolant is recommended as it is appropriately formulated for our aluminum block engines to minimize electrolysis and wear of the aluminum block. BMW coolant is concentrated and requires dilution with distilled water to a 50/50 mix. Distilled water is recommended as it removes any impurities from the water that may promote electrolysis.


Once the float indicates full and coolant emits from the bleed screw, replace the cap and close the bleed screw. Be sure not to overtighten or strip out the bleed screw.

According to the E46 Owner’s manual “The coolant level is correct when the upper end of red float is at least even with the upper edge of the filler neck. The end of the float may stick out a maximum of ¾” inch" – that is, up to the second mark on the float.

Start the car and crank the heat. Let the car run for about ten minutes. Watch for indication of leakage from the cap or bleed screw. If the low coolant light comes on while the car is running, turn off the car and check the level.

Turn off the car and repeat fill and bleed procedure as described above to verify the system is full.

[ryankokesh]

I think I'm doing it wrong... when I'm pouring the coolant in, nothing is coming out of the bleed screw (even thought I totally removed it) until the coolant is almost to the top of the expansion tank. As in I was careful putting the cap back on for fear of coolant leaking out. So I poured in a lot more coolant than was necessary to get the second ball to the top of the neck. My Bentley just says to keep adding until fluid comes out of the bleed screw. But then I'm past "max".

[ryankokesh]

So I sucked some coolant out after I tightened the bleed screw. I got the stick to be at the right ball, and tightened it up. The car still didn't get up to temp, so I'm guessing the thermostat is actually stuck open. I was fairly certain this was the case, so not a big surprise. Only thing was the the hose from the thermostat to the expansion tank was fairly squeezable after I let the car run for a min or so. I thought it was supposed to be really hard to squeeze, as if it were pressurized?

[kayger12]

You were doing the right thing.

Keep pouring in coolant until it comes out of the bleed screw. It will look like you're over-filling the exp tank.

Start the car when you're done and let it run for a couple of minutes, then check the coolant level and adjust as necessary.



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[ryankokesh]

Thanks for the info! Do I ever open the bleed screw with the car running?


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