Having torn one apart, what would you say is the best way to clean it out without tearing the whole interior apart to remove it?? Do you think it is possible to clean it out with a product or are we stuck replacing??

 

We have not tried it but it does seem that using the CLR or BG cooling system cleaner and the bottles is a good way to do it. We found when just pooring cooling system cleaner into the car and letting it run does not seem work very well. The way the system is designed the coolant/cleaner can bypass the heater core. Clamping off the top radiator hose does seem to force more cleaner through the heater core, you just have to make sure the car does not overheat. The best way is to isolate the heater core and send the cleaner through it both ways, which the bottle system does. I have been kicking around the idea of building a heater core flush system with a higher pressure external electric pump that could be hooked up and flush the core both ways. Which is really what the bottles are doing, but in a more automated way.

 

Hello,

I recently just had the same problem fixed on my 2002 audi a4. I had my garage backflush the heater core and my heat is now good and hot. He also did a full engine coolant flush as he said the coolant was gunked up a good bit. Maybe this would help?

 

Wow...I just bought a B6 yesterday and found no problems, until I was headed home and the heater wouldn't get hot...Not much of a person for taking cars to shops, but hopefully I can get this fixed now that its winter!

 

Same problem on my B6. No heat. I will be attempting this heater core flush and share the results. Inlet and Outlet hoses are easily accessible so should not be a problem.

Will coolant start pouring out once i remove these hoses?

 

You will get a little coolant out but not too much when you remove the hoses. This is a high point in the system. The key is to keep forcing a cleaner through the heater core. You may get what appears to be good flow, but the coolant will not be flowing through enough of the heater core to get good heat.

 

Heat! Heater core flush works. Flushed water through inlet and outlet until clear. Initially, rusty flakes and brown water was flowing out. Used CLR and let sit for 30 mins. Flowed water again. Attached hoses back together and bled the system using the air hole method.

Hot air is blowing with big grin on my face although its 60 out in california.

Thanks again guys, once again, i saved some money. i'll click some ads for you guys..

 

Performed flush, got heat now intermittenly. I've also developed this wierd overheating issue. The car runs fine at idle. Under load though it begins to overheat, but once I pull over returns back to normal. I've also found the heat will come and go during these times. Any ideas????

 

I flushed the heater core and the key to bleeding the coolant system is to hold the RPM at 2000 and bleed at both the solid coolant line and at the return line from the heater core. Or at least that worked for me!