Best way to bleed cooling system 1.8T? Pressure or Vacuum?

[slcrobo]

I have been fighting what I assume is an air pocket for days? This all started with a coolant flange change. Upper hose on radiator hot, lower hose ambient temp. Temp spikes while driving. Changed thermostat thinking may be the problem, nope. Sucked it down twice and refilled via vacuum, now no heat. Did the best I could going systematically through the coolant system looking for a clog and there appears to be none. (I did get a small amount of debris out of the heater core). The water pump impeller seems to be intact and not free from the shaft, unless as water temp increases the impeller begins to slip on the shaft. Is there a way to ensure water pump is moving coolant? Any thoughts or suggestions?? Thanks in advance.

[sinistervii]

unscrew the coolant resivour and tilt up to where the coolant input hole is at the highest point.

take coolant cap off

start car and let warm up

After a few minutes you will see bubbles in the coolant return line. (the skinny top one)

the black coolant pipe that runs between the intake manifold and the valve cover there is an alan screw

open barely enough until you see coolant pouring out a little bit

wait maybe 30 seconds and close.

Turn heater one lowest setting

(this is how I do mine and it has worked every time. )

[sa_seahawker]

unscrew the coolant resivour and tilt up to where the coolant input hole is at the highest point.

take coolant cap off

start car and let warm up

After a few minutes you will see bubbles in the coolant return line. (the skinny top one)

the black coolant pipe that runs between the intake manifold and the valve cover there is an alan screw

open barely enough until you see coolant pouring out a little bit

wait maybe 30 seconds and close.

Turn heater one lowest setting

(this is how I do mine and it has worked every time. )

I did mine a little differently. I kept getting air into my system that way.

With cold system, unscrew bleeder valve, pour in coolant until it starts flowing out of bleeder valve.

Tight bleeder valve, cap coolant reservoir, turn on motor and rev at 2000 RPMs for a couple minutes with heat full blast.

Turn off. Let it cool down and top off as necessary.

[slcrobo]

I have done all this. I can fill it with vac. and it seems coolant wont circulate and pipe over intake is empty. I can add more coolant through the bleeder screw (which should get coolant to the pump, prime the pump) then I get hot water in and out of heater core, but it still seems that the thermostat is never opening. Could i have purchased a bunk themostat? seems a bit crazy but i guess it is possible.

[refueler]

This sounds a lot like the problem that I was having with my 1.8 B 6 did your problem start out with loosing a small amount of coolant. My car was loosing about 500 ml 0f coolant a week so I looked around for a leak, but never could find one that left a puddle any where or any evidence of a leak. So I changed the rear coolant flange and I could not bleed the air out of the system either. I tried everything there is a bleed hole on the hard pipe as well as the one on the heater core outlet hose I probably bled a gallon or more of coolant through those holes. I tried blowing air back through the heater core and I also got some junk out of the heater inlet but that didn't help. Then I was discouraged so I sent it to a local mechanic he looked at it for a couple of hours he sent it back saying either there was a blockage somewhere or the thermostat needed to be changed(no charge yeah). So I changed the thermostat still no heat. Next I sent it to another shop for a power flush of the heater core again no help. Diagnostigator suggested that I might have a head gasket/head problem so I made an adapter to pressurize the cylinders to see if air bubbles would appear in the coolant expansion tank. It didn't take long the # 2 cylinder had bubbles appear in the expansion tank when pressurized. So my next step is to remove the head and find out whats going on. Take a look and see if that's your problem because you described my problems. Good luck in solving your heat problems.

[slcrobo]

You nailed it refueler, #2 cyl pressurizing cooling system.

[monty2982]

What did you use to make an adapter to pressure test the cylinders?