Thread: How to bleed the cooling system?

Guys, I'm kinda confused on how to do this.
Accoring to my understanding, with the car running and radiator cap off, I open the bleeder valve and expect something to come out of it. But when I do this, water comes gushing out of the radiator.

So just what is the process of bleeding the system?

Really, you want to remove the radiator cap and run the engine to operating temp, rev it a few times from under the hood, and make sure no bubbles are coming out of the radiator fill. When the bubbles are done, so are you. Just make sure to keep adding coolant as the bubbles work themselves out, and refill the overflow.

That's my method.

Yeah, basically i'd open the overfill reservoir cap and get the motor stupid hot. Then shut it off right before she boils over.. coolant gets sucked into the motor when you turn it off.

Do it again and again until coolant no longer dissapears into the motor.

This was necessary on my BMW. It sucked down about an entire gallon this way. If i wolda not completely bled it.. the car would have had maybe 10% coolant actually in the engine and 90% air bubble.. lol

The nissan service manual has the absolute best way. A summary :

With the bleed bolt removed from the thermostat housing and the heater set to full hot on the dial (identified by the bolt with the copper washer under the head, also sometimes there is a stick with an arrow, but these can come off...) fill the cooling system slowly and progressively until a constant stream of coolant comes out (i use a thick rag to catch it).
Re-install the bleed screw quickly and tighten to the appropriate torque.
Continue to fill the cooling system until the coolant rises in the neck. Gently squeeze each of the hoses a little to push some more bubbles out and top up.

Fill the coolant bottle to the max line.

Using a paper clip or the end of a cable tie (about 1/2" long piece) lift the metal centre valve on the radiator cap that usually opens to allow cooalnt to flow back into the cooling system during cool down and put the clip or piece of cable tie or other bit in there to jam it open slightly.

Install the cap back on and start to squeeze and hold the radiator hoses. you will note that LOTS of bubbles will flow out and bubble up in the coolant tank. When you release the hose (after holding it squeezed for a second or two) it will suck *only* coolant back into the cooling system. I do this to each hose a few times to get the majority of the bubbles out. I then start the car, let it rise to thermostat temp and during warm up continue to squeeze the hose and push the bubbles out.

You'll notice the level on the coolant bottle will drop as the air blown out and the coolant is sucked in.

Once you're happy that a majority of the bubbles are out, remove the cap, remove the shim/paperclip/cable tie piece, reinstall the cap and warm the motor right by taking it for a drive. You should notice that on the next cooldown cycle the level will drop even futher and the coolant tank might need to be topped up.

Hope that helps you guys out. I've used this method for YEARS and i've never, ever had an issue (plus it can't be all bad as its how the FSM says to do it!)

interesting ways. I never really got the car hot so maybe I'll try that.

Cozzmo's way is rather overcomplicated, but works just as well. Personally I'd run it with the cap off so I can better monitor the coolant and fill it quicker. Does the same thing but generally saves time. The bleed screw is something I forgot to mention, though, and is ridiculously handy.

i want to do that for use my water wetter

The way I found best is with the car off, take the bleeder off, dump in coolant until it comes pouring out the bleeder, cap off the bleeder, fire it up, get it nice and hot and watch for bubbles. I've done it that way many times and very rarely do I get any bubbles.

Doing it with the reservoir cap off is a hell of a lot less potentially messy.

May take a little longer to do though.

The service manual description of it is far better, and with the aid of pictures cuts down what i've explain to a couple of pics and about 10 lines of text.