Allroad no heat after overheat - flush heater core

[vtraudt]

Car froze up, overheated. All coolant gone.
New waterpump, fresh coolant. Engine bled. Several heat up cycles, driving.
No codes, no overheating.
No heat.

Suggestions?

a) air in heater core, hope it ill clear itself out
b) heater core plugged from overheat/dry. Flush to clear and restore flow. Is there an easy way to flush the core? Or does it have to be done through the 2 lines in the back of engine? IIRC, both lines connect to the block with the push/clip connector, so no easy way to hook up a 'flush hose'.

Assume a) is not an option (may not work or may take too long; no heat), looking for good ideas to tackle b)

[AustinAllroad]

Following

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[ruiz]

The heater core pipes that you connect hoses to are behind the firewall next to the battery under an accordion type of cover. Here's a video of the core being flushed: https://www.youtube.com/watch?v=M7MArQFs9Lc

[AustinAllroad]

Awesome

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[vtraudt]

The heater core pipes that you connect hoses to are behind the firewall next to the battery under an accordion type of cover. Here's a video of the core being flushed: https://www.youtube.com/watch?v=M7MArQFs9Lc

Thanks! Hah, never paid attention to it on the 2.7T. Will tackle later today (just a lot less fun to do in freezing temps).

[Nemesis2747]

I went into the drivers footwell and removed the core for my flush. I had to shake it hard to get all of that hardend gunk out. Not hard to do but a pain in the ass since u pretty much have to lay on your back with your head next to the pedals.

[vtraudt]

I went into the drivers footwell and removed the core for my flush. I had to shake it hard to get all of that hardend gunk out. Not hard to do but a pain in the ass since u pretty much have to lay on your back with your head next to the pedals.

You were able to remove the CORE that easy (driver side footwell?). Wow. Thought that is a MAJOR job. Just for reference: is there a good DIY you used?

[vtraudt]

[QUOTE=Nemesis2747;12089073]removed the core for my flush. I had to shake it hard to get all of that hardend gunk out./QUOTE]
This car has 180k miles (and 13 years old), so obviously no surprise if gunk now has plugged the passages. What is the general consensus on using chemicals? CLR is mentioned often.

[quattro16]

Change the heater core and be done with it. Not too hard to do....

[Nemesis2747]

You were able to remove the CORE that easy (driver side footwell?). Wow. Thought that is a MAJOR job. Just for reference: is there a good DIY you used?
Heres my thread.

http://www.audizine.com/forum/showthread.php/735482-Winter-is-Coming-and-heat-sucks

But if you would trade some money to save time, buying a new core is just remove and replace.

And i used CLR. but even soaking it for 20 min at a time and rinsing, very little came out. Had great results by filling it half way and shaking the crap out of it, literally.

[Grainreaper]

I'm planning on flushing my core next week when the shop will be pretty dead (fingers crossed) naturally I planned on doing it long before winter started but I got sidetracked with other projects, and work has kept me crazy busy with customer cars.... I hate it when I'm late for the last minute stuff.

[vtraudt]

If using CLR flush: how long should it stay in? I run circulation pump to flush. Keep it in/running for 30 min?
What concentration? 1/2 bottle in 5 gal pail?

[Nemesis2747]

If using CLR flush: how long should it stay in? I run circulation pump to flush. Keep it in/running for 30 min?
What concentration? 1/2 bottle in 5 gal pail?

Well thats the funny one. From what i read, the heater core is aluminum. And CLR eats aluminum. First time i did it with a pump back flushing the core with 50/50 hot water for 15 min, twice. Didnt do much but did clear out some gunk and improved heat a little. When i took the core out i filled it with with clr only for 30 min and that water turned BROWN. But still little improvement. Try high pressure ( like a hose NOT pressure washer) water and back flush it for a while.

[vtraudt]

Heres my thread.

http://www.audizine.com/forum/showthread.php/735482-Winter-is-Coming-and-heat-sucks

But if you would trade some money to save time, buying a new core is just remove and replace.

And i used CLR. but even soaking it for 20 min at a time and rinsing, very little came out. Had great results by filling it half way and shaking the crap out of it, literally.

So shake more effective that chemical aspect? I did flush forward/backward for about 10 min each with high volume submersible pump (closed loop), warm water. Not impressed with heat. In spring, maybe give CLR a try for 20 min. Not only soaking, but rather high volume flushing.

[Nemesis2747]

So shake more effective that chemical aspect? I did flush forward/backward for about 10 min each with high volume submersible pump (closed loop), warm water. Not impressed with heat. In spring, maybe give CLR a try for 20 min. Not only soaking, but rather high volume flushing.

Im always reading that sediment settles in the core. If u see my video in the thread u can see what that stuff looks like. I dont think chemicals alone will take care of that. Either fast hard plusing water to break it loose or shaking it up. Maybe flushing it and tapping the core lightly but firmly or vibrating it would work better i think.

[Grainreaper]

Ultrasonic cleaning would be ideal, I'd imagine... I have to see how big the tank we have at work is.