As some of u guys know I changed last month my thermostat with success. But ive been having some problems.
1st. when the coolant expands it wont expand like stock the flow is intermitent like comes and goes continuous i thought bleeding the system might do the trick? i tried finding a bleed screw on the coolant hose that is on top of the engine under the engine cover but there is no screw? i proceeded with the heater core hole in the tube by removing it until its clear from the nipple and turning the engine with the heater at full blast. nothing comes out though no coolant. But as soon as i rev the engine coolant squirts from the little hole. Ive try milking the upper radiator hose and you can see coolant squirts a bit. THe thing with all this is that the temperature in the cluster acts weird sometimes it warms to the middle and sometimes drop cold. I changed the thermostat because i was having this problem with the one it had. oil temp gets normal though. Oh and no codes coming up on vag com. My car is an AWM engine a4 1.8t 2001

Need help guys!!! Im upgrading the turbo this month

here's a vid sorry for crappy iphone cam

http://qik.com/video/10298013

 

Bump?

 

When I bleed my system using the hole at the top of one of the heater hoses, at the start I got a few air bubbles like soapy bubbles, then a stream, then nothing. If I rev it, once you go back to idle, you get a stream of water coming out, then nothing, no coolant, no air. Does that sound right?

 

manual says to turn the heater to high first. then rev motor @ 1200 for 2 minutes. Pull open hose with hole until there is steady stream then close. Let cool a few minutes then just open the fluid cap for a half a second just until you hear a swoosh. Then let car cool. Then top off fluid. The swoosh is the vacume created by the fluid cool down will force the air blocks our of fluid levels and eliminate the gurgling sound on cooler days...
There should be no air in the system other wise there is a gurgling sound when heater is on. the air hole works to bring the fluld up to that level like a syphon. The swoosh will flush the rest of the air out of the heater core area. to complete the air free process.

 

I have a theory I would like to pose to this thread, as I have a 2001 A4, 1.8T also. I am about to change out my thermostat as I get tendencies from my car to gravitate towards overheating mostly when driving around town, but not so much on the highway. I am thinking that after I change out the thermostat that I can probably bleed my coolant system by unscrewing the reservoir and lifting it up ABOVE the level of the heater core while the car is running. Being that the reservoir will be the NEW highest point in the system, the air SHOULD rush to IT and finally escape. Anyone ever try this method before?

 

Interesting theory. Maybe it will work. But just on your point about the thermostat, my understanding is that if / when the thermostat fails in these cars (AEB), it fails in the open position.

 

Keeping the coolant reservoir above everything else is a good idea (which is why it's almost there already) but the problem lies in coolant/hoses that go up then come back down, like an upside-down 'U'. The air can get caught in there and won't rush out because it's already at the highest point it can get to without going down.

That's when you need to utilize the little bleeder screws OR some sort of force, like suction to get it he air out of those little pockets. And yes, if the air bubbles in those little areas are small enough, the force of the moving coolant will push them out naturally, but not if the air bubbles are too big.