"burping" cooling system on 83 944

[nathan944]

Could someone be so kind as to tell me how this phenomena is performed. Thanks.

[CT944]

basically: run car with heat on full blast, wait until fans come on. once fans come on and you feel the heat blowing from the dash, open the upper radiator bleeder valve (it's red). keep the coolant reservoir full. when there is a steady stream of coolant coming out of the bleeder valve, close it and that's it. fill the reservoir.

[unclebilly]

On my 87, there was a bleeder screw on top of the thermostat housing.

[Macfreak007]

best way is to go to autozone and rent a radiator pressure testor, free rental. Pump it up to 10psi on a cold engine and open that valve. easy as can be...

[sayporsha]

once fans come on and you feel the heat blowing from the dash, open the upper radiator bleeder valve

If you wait for the fans to come on you risk cracking your cylinder head. An air pocket will prevent coolant from reaching the passages in the cylinder head and it will overheat.

This procedure should be done whenever the cooling system is refilled (after repair, flushing, etc.). In my experience bleeding my 968 and 951, I have found that it requires several bleedings to get all the air out. It can be accomplished in 1 warmup cycle, though. Small bubbles throughout the cooling system slowly make their way to the highest point on the engine: the cylinder head. They accumulate there, forming an air pocket. The air pocket must be bled occasionally during warmup to prevent it from getting too large. Coolant must be added during the process to displace the air.

Here's the process I found to work best:
Turn the heater control to full hot. Make sure the rear of the car is not higher than the front. Open the bleeder valve while refilling (or topping off) the cooling system. The valve looks like a bolt going into the coolant elbow that attaches to the head. Close the valve when what comes out of it is more coolant than bubbles. Start the car with the reservoir cap off. Every few minutes, open the valve to let more air out. Close it when clear coolant runs out. Top off the reservoir to keep the level up. Repeat this process until no more air comes out. If you raise the engine speed it makes foam in the air pocket. Be sure any foam settles before the final bleed. The air is usually gone by the time the radiator fans come on.

Next time the car is stone cold, top off the reservoir one last time because the coolant level drops slightly after cooling. Now you're good to go.

[Brian J]

After using the procedure in the owners manual and the procedure in the Hayes manual (both did not work) I was given this much easier and effective way.

1. make sure the rear is not higher than the front
2. set the heater controls to hot
3. open the bleeder valve
4. fill the resevoir to the "Maximum level"
5. replace the resevoir cap.
6. pull out the overlfow tube and blow on the tube
7. when all the bubbles quit and a steady stream of coolant comes out of the bleeder valve. close the valve while keeping the presssure on the overflow tube.
8. Run the car until hot.
9 Let cool.
10. Repeat if necessary

[bjenkins]

I used a vaccuum pump at the bleeder valve to suck the air out until coolant started coming out. Worked perfectly for me.

[TCMdocs944]

Originally posted by unclebilly
On my 87, there was a bleeder screw on top of the thermostat housing.

That appears to be the thermostat housing but it is not...your thermostat is at the bottom of the head near the oil cooler

[TCMdocs944]

Originally posted by CT944
basically: open the upper radiator bleeder valve (it's red).

Yours was painted red by a PO.

The screw will either be in the upper housing on the head (if updated by a po) or in the actual upper radiator hose...You can still get that part but most have been updated.

[TCMdocs944]

Another tip on the earlies...If you are not getting proper cooling after following the above 'burp' sequences, jack up the pass. side of the car when warm. This has alleviated a rather large bubble for me 2x.

[todd84944]

My way...
On early cars, turn the heater control to hot. (valve opens without car running on early cars)
take bleeder screw off
fill jug till it can't take anymore.
squeeze upper hose tight, place finger over bleeder hole, let go of hose. Hold finger over bleeder hole till level in jug stops dropping.
Do this several times.
I can get all of 2 gallons in without having to start the car. Each time you squeeze the hose and hold your finger on top of the bleeder hole, keep it on there till the level in the jug stops dropping. What you are doing is forcing the coolant into the head and the rest of the motor. You might have to bleed it one more time, but that will be it.

[bearone2]

by jug do you mean the coolant tank or a jug/hose filling the coolant tank.

[TCMdocs944]

Probably coolant tank.

I am a squeezer too. Really helps to draw the fluid into the top of the head. I still want to come up with at valve system that screws into the bleeder that is easy to fill.

[nathan944]

I think I have got it now. Runs on highway around 150-160. Jumps to 180 if it idles for awhile and the fans kick in at 180. This sound OK?

[todd84944]

Sounds like we have a winner!!!!

[nathan944]

yay