Can I blow out my heater core with air?

[NSTDI]

My passenger side is pumping cool air, is there an in and out connection that is accessible that I can try to blow out the core with very gentle air pressure? Disconnect the in and out and blow air through, say 1-5 lbs?

I’ve tested heater cores this way to see if they hold about 10-12lbs overnight. But I’d rather not mess with removing the core and I will have nice clean distilled water in the whole system so thought I may be able to flush my core. I’m doing a flush and fill with new G13.
Thanks for any help.
Don

 

[AverageAndy]

I don't think blowing air through the core would help. Some have suggested disconnecting heater core at the firewall side connections, then back filling it with something like Permatex 80030 Heavy Duty Radiator Cleaner. After letting that sit, then one would flush with water in the reverse of normal coolant flow to get out all the blockages. See this post for more description:

Mixed/contaminated coolant can clog up cores on the gassers, too. I just flushed one on a 2015 2.slo Jetta that had been previously messed up by morons. So yeah, it can happen on those.

I have been reasonably successful with flushing them the opposite direction of flow with a garden hose after soaking them with Permatex Heavy Duty radiator cleaner.

Amazon.com

That stuff is powerful, and it works. I *JUST* put it in the heater core/pipes, and not anywhere else. Yes, I know it says not safe for aluminum, and yes I know the pipes and core are made out of aluminum. I don't leave it in there for very long, and if it messed something up (never has, but if) you'd be back to replacing it anyway, so what is the harm in trying?

Here is how I do it:

Disconnect both quick couplers at the heater core pipes on the firewall, and move them out of the way and secure them so nothing else gets in them.

Get two lengths of bulk hose, about a foot or so long, 3/4"/19mm ID, and slip them on to each pipe, and angle them UP.

Pour the cleaner down both hoses until they are both full. If the core is not completely clogged shut, which they usually are not, just pouring it in one hose is enough, as liquid seeks its own level and it will come back up the other. Try not to spill any. One quart bottle is enough to do it a couple times at least.

Let it soak for about 20 minutes. You may see some bubbles and foam come up as it dissolves the solids inside. Pull the hose off from the TOP pipe connection, leave the lower one in place.

Rig up a garden hose to fit in the hose that is still attached to the BOTTOM pipe, then turn it on full while watching what comes out of that top connection. You'll see a black/brown slurry of filth come pouring out... keep the hose running until it comes out clean and clear.

Turn the water off, remove the hose, reconnect the quick couplers, refill the system with G12 mix, put anything back together you had to remove to get at the firewall, take the car for a drive and make sure the system is full.

 

[NSTDI]

Thanks Andy. I was thinking air would create a path through the core and then a good flush with water. I’m assuming this clog is not something that is rock hard but obviously that is a big guess/hope.

 

[Lightflyer1]

Air will easily go around things and water won't so much. Spraying air into it will more than likely do nothing unless it is completely blocked off and builds some pressure. Not exactly what you want to do to much. Soaking it in vinegar and cleaning it out over and over might help. Acetic acid in it might do the job. Just be careful and have a plan.

 

[x1800MODMY360x]

Also G13 coolant isn't a great choice for these cars. Bought my car from a small TDI shop and he uses G12. I owned it for 9 months so far, no issues.

 

[Jaytechqu]

Also G13 coolant isn't a great choice for these cars. Bought my car from a small TDI shop and he uses G12. I owned it for 9 months so far, no issues.

Doesn't matter what coolant you use, the coolant system in these late model TDIs was TERRIBLE!! The passages in the heater core are just too narrow n will need to be replaced every couple years or sooner!

 

[Mongler98]

better to just use a hose and funnel and dour in distilled to flush it clean... air does very little to move liquids around compared to another liquid.