tarpeyphoto

2003 a4 avant 1.8t quattro, 105k, owned since 87k.

Timing belt and waterpump done at 80k by dealership (I have the paperwork from the previous owner).

Tried flushing the heater core before any of this bleeding. Water flowed through, and came out clear after a bit of gunk came out. Made no difference in heat.

Temp gauge operates normally.

I've read around quite a bit trying to find an answer for this, but couldn't come up with a concrete answer, so I figured I'd ask. Thanks in advance for any help.

Basically my heat is not blowing hot, and I keep reading about air being in the system being a leading cause of that. If I turn the heat on high, but the fan on low, you can feel a bit of hot air kind of hovering around the vents. But if you turn the fan up higher, the air quickly goes to luke warm.

There is definitely a good chance that there is air in the system, as I replaced the coolant flange and the sensor that sits in the coolant flange sometime last summer, and I never bled the system after that, as I didn't realize I had to.

Here is what I've tried:

I bled it from the small hole in the hose that comes off of the heater core. With the car parked, I would hold the motor around 3500rpm for 3-5 minutes at a time to get the motor hot, then would slide the hose back to release a stream of hot coolant. Occasionally hot air would come out, and occasionally it seemed like nothing would come out? It would go back and forth between coolant, hot air, and nothing in no particular order. Did this probably 10-15 times, heat never got any better.

Next I read something about "burping" the coolant system by driving the car around to get the motor hot, and then stopping, and just turning the coolant reservoir cap enough to where it releases the pressure. At the same time I read about this, I read about the small allen head bolt you can loosen on the hard coolant line that runs across the top of the motor. So this time, I would drive the car for about 10 minutes, keeping the rpm's between 2500-4000 to get the motor hot. Then I would park, and turn that screw on the coolant line about a half turn, a lot of hot air was definitely being released from there. Then I would also "burp" the coolant system as I described in the beginning of this paragraph, which seemed to produce some gurgling in the system. This seemed like it was helping, but it was also around 55 degrees F outside.

So basically I'm asking if there is a tried and true method for bleeding the air out of these coolant systems, and what the heck is it?!

Again, thanks in advance for any help!

Howard

Prospeeder

If you have driven the car, hit high rpms a few times. Its bled. I work on these cars fora living and have yet to ever do anything specific to bleed the cooling system. Just fill and drive, then top off again. Its the heater core thats bad. They pack full of debris and flushing doesnt do anything, its full of what looks like pasta noodles to slow water flow down and it just causes it to block up. All the tubes run parallel so the flow your seeing is the 3-4 tubes that actually flow. I see this alot, A4's and Passats seem to be the only ones that do it, never had an A6 or any of the VW cars do it.

tarpeyphoto

Thanks for the reply! So all these other people blabbing about bleeding this and that are just out of their minds?

lyleswk

My experience doing my own maintenance twice on timing belts, twice on aft coolant flanges, and 1 heater core line is the same as Prospeeder's. It may not immediately work, but if you have driven it some, it is "bled".

tarpeyphoto

Check out the picture, that is what I used to blow all the crap out of my heater core, and now my heat is kicking ***.

My brother and I put together this rig to blast air/water through the heater core, and it worked great. All parts can be bought at a hardware store.

Used on:
1998 1.8t quattro sedan
2003 1.8t quattro avant

Remove the hoses from the heater core. Hook up the side with the water and air attachments to the "in", and then the extra piece of hose to the "out" of the heater core. Let some water in, turn the water off, then blast the water through with the air. If you put the other end of tube into a clear jug, you will be able to see all the crap coming out of your heater core. Repeat until the water that is coming out is free of any debris.

Again this worked for me, I can't guarantee it will work for you, but it's probably worth a shot!

Thanks,

Howard