Bleeding Cooling System

[2RUNE34]

A better way to do this is to disconnect the small tub that runs from the reservoir to the radiator from the reservoir. Fill the reservoir with coolant and put the cap on. With the front of the car at least one 1' higher than the rear apply pressure to that tubing (blow into it) until coolant is flowing from the bleed screw and and the top of the radiator. It is important to have the front end of the car up in the air so that the radiator and bleed screw are the highest points.

Note that this won't clear ar from the heater core. To accomplish that you have to follow the normal bleed procedure (see below).

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.

Hey all I am a new member here on r3vlimited. I have a 1990 BMW 525i with the m20 engine. I have a question about bleeding...I have seen another forum member post the easy way to bleed the cooling system from a thread a long time ago. He says to open the thermostat bleed screw and add coolant until no air bubbles come out. Here is where I get confused, the engine is off but in step 3 he says to turn on max heat and when the engine gets warm start the car. So my question is, how does the engine get warm when it is off? Does he mean when the heater starts blowing hot air or what? I'd like to know because I'm not very good at bleeding the car and my indy said I need to use BMW coolant. He also said my radiator is cracked and is leaking coolant, but I see no signs of leakage and the coolant level has stayed the same for months.

[AndrewBird]

The engine needs to be running.

Why do you think you need to bleed the system? Is the car overheating?

[2RUNE34]

Well how would the engine be on if he says start the engine and allow it to warm up to operating temperature? No the car is not overheating it's just that I'm worried that it will since the mechanic said my radiator is cracked and that I should use BMW coolant. Also the engine temp goes over the middle mark by about a toothpick width but no where near the third line or the red area.

[xxx-Lost-Soul-xxx]

When he says "get to operating temp" thats the middle of the gauge 190-210' temp
If your car isnt getting over the middle then there is no reason to bleed it.

If your radiator is cracked, Go buy a new one. They are $170 shipped for a OEM one that will last 12 years.

This is a cheap stupid eazy fix,that is a no brainer,if you keep letting your radiator leak. You risk the chance of fucking your head up.

And someone from R3V coming to repo your car. IM NOT JOKING IT HAS HAPPENED.

[2RUNE34]

My Indy said it was cracked but I see no sign of leakage anywhere. Also my question is "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.
How does the engine heat up if it has not been started yet? That is my main question I understand all of the other steps!

[AndrewBird]

You are making this WAY more complicated that it needs to be. Do this:

Put the front of the car up on jack stands or ramps. Remove the coolant cap and fill the overflow with coolant if it is low. Leave the cap off and start the car. Let the car get up to normal operating temp (gauge at half way or so) and add coolant as needed. The engine may suck some coolant out of the overflow bottle as it warms up.

Another way to be sure the engine is fully warm is both radiator hoses will be warm/hot to the touch. One will be cold until the engine warms up and the thermostat opens.

Be sure to have the heater set to full hot. This allows coolant to flow through the heater core as well.

[2RUNE34]

Well that makes more sense now! Before I bled the car I would close the radiator cap so I guess that's why the temp always rose up quickly no matter how many times I opened the t-stat bleed screw. I made this thread so that in the future if I ever needed to bleed the car I would know what to do, other than that my car runs fine and doesn't need to be bled at all at this time. Thank you for clarifying. Also NitroRustlerDriver do you have your own method to bleed your car or do you use those steps that you told me?

[AndrewBird]

I use the steps I gave you. Never had a problem with air getting trapped, using this method on multiple different cars.

[2RUNE34]

Ok and as the engine temp rises, you occasionally open the bleed screw on the t-stat right?

[2RUNE34]

Ok so yesterday I finally had to re bleed my cooling system because the fan made a hole in the upper hose, and I tried the method but it didn't work and coolant would just pour out of the expansion tank.