Burping

[scruffboy]

If the weather is nice this weekend I'd like to try to burp my car. I definitely hear water gurgling in the dash. Mr.Nickleye used ramps but I liked Supragirls poor mans solution of a steep hill. Can I drain the coolant out before I get to the hill, I don't want to do that in front of some strangers house. I have a really steep hill 2 short blocks from my house, which should definitely put the core below the rad cap. So I take the cap off and idle for 20 minutes. What exactly am I looking to see happen? How will I know when I'm done? Should I be pouring coolant in as this is happening? Any tips or tricks of the trade would be very welcome.

Thanks Guys and Gals

[j3pz]

you dont need a steep hill. just something the get the front end up; jack stands would work. my drive way is slightly sloped, so i used a set of ramps the increas the slope more. once its in the air, just let it idle for a while. if you want, you can fill it (the radiator) up before you start, and watch the bubbles come out the top of the radiator. once it stops it should have all the bubbles out. thats all i got to throw in

[Supra2NR]

Have 2 gallons of coolant ready cuz u don't know how much air is in there
And you will be losing coolant in the process as the bubbles come out of the radiator

And a pan underneath the car so you won't make too much of a mess

I never got to ask this when I was burping mine:
Is it necesarry to have the heat a full blast, when burping it?
If yes, what for?

[dcrusupra]

You need the heat on full blast. I'm not sure why but I think it's because it opens up a new path of hoses that the air would pass thru to get heated.

[j3pz]

oh ya what he said^^^


you have the heat on high because it opens up the lines through the heater core, or so ive read. this allows the air to be flushed

[IHateHacks]

You shouldn't have to burp your cooling system unless you just performed work on it and opened it up. If you are just getting the waterfall sound for no reason except for driving it, then you have a problem.

And I really think this crazy "burping" method is a crock, no disrespect to suprra girl or anyone else. I just replaced my head gasket and after 2 or 3 heat cycles (driving for an hour, let it sit overnight) my cooling system bled itself, just like any other water cooled engine would. When an engine gets hot it spits the overheated coolant into the coolant overflow bottle, then when it totally cools down it sucks it back into the engine from the overflow and thats when the system bleeds itself. Now if you have a leak somewhere either internal or external during this cool down, it won't suck the coolant from the overflow, it will suck air from where ever its leaking from. 9 times out of 10 (with a MK3 supra) it will be from a blown head gasket. I'm anal when it comes to cooling systems (actually Im pretty much anal about everything) and I've studied how cooling systems work first hand, and every single car/truck acts the same unless there is something wrong, like in my case a blown head gasket. I check my overflow everytime I heat the car up and get to my destination to make sure its at the same place the last time I drove it, its a bad habit and people are always wondering why I'm looking under the hood. And I always look at the overflow in the morning before I start it up, making sure its at the same place it was the morning before.

Have fun on that hill......

[mrnickleye]

Ihatehacks Quote: And I really think this crazy "burping" method is a crock, no disrespect to suprra girl or anyone else.

You were lucky with yours. Probably because air did not enter the heater core during the BHG repair.

I've been lucky on mine a couple of times during coolant drains (like radiator swap).

Most are NOT so lucky.

The problem with the MKIII Supra is that the top of the heater core is located higher than the radiator cap.

So, whenever the coolant has been drained, air gets trapped in the top of the heater core. The gurgle sound is the coolant and air bubbling around in the core. This is VERY BAD for the core, as it will cause it to corrode and leak.

To remove ALL the air, you must get the top of the heater core lower than the radiator cap to allow the trapped air out of the system.

MANY cars have places in the cooling system that are higher than the radiator cap, and have to be burped. MANY also have 'air-bleed' screws/valves on the high spot, to let out the air. Usually on the highest place on the engine that has coolant flowing thru.

I usually give mine a few revs (1500rpms) during the process to speed the coolant up a bit, and force the air on thru the plumbing.

NOTE: If you rev too much, it will 'whale spout' when you let back off.

I found that if you stick a piece of folded matchbook in the throttle stop (on the throttlebody), and set the idle to 1000rpm, it works best. This is because the water pump does not move very much coolant at 6-800rpm.

[IHateHacks]

Originally Posted by mrnickleye

Probably because air did not enter the heater core during the BHG repair.

Oh it most certainly did, I had all my heater hoses off and I watched coolant drain out of the the core. Sorry, not trying to prove you wrong, just stating what happened.

I do know that some, not all, engines use bleed screws, usually they are on the top of the thermostat housing. I still never use them, and I never had a problem bleeding the coolant with the "time" method I use. Yes, I know that there are quicker ways to bleed coolant, but my method is a fool proof way of getting every last air bubble out of the system. It may take 2 days but it works.