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heater core flush success

18K views 16 replies 9 participants last post by  Tomvw 
#1 ·
Living in NJ with winter approaching , and "ok" heat ( I get like 118 degrees from vents at cruising speed, at idle gets very weak, and takes a long time to attain that) I decided to do a flush yesterday with outside temp around 65. I used the CLR & air / water gun tool. Poured in the CLR and let sit for about 45 minutes. Next I reversed flushed with the gun and intermittent bursts of air for about 8 - 5 gallon buckets full. Then forward flushed for a few, and went back to the back flush to finish up. Had a socked wrapped around the outlet hose to filter out stuff I was getting to see my results, got some pretty nasty junk and a good amount of it. So far so good, last night and this morning I'm getting 150 degrees at idle from the vents, last night outside temp was about 55, this morning about 38. Hope that it holds up when the temp really dips. I know in the past even with the "ok" heat when the temp really drops, it takes a long time to get to a tolerable temp in the cabin.

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#7 ·
I am doing mine right now. I've had success twice before and its been a couple of years since the last time, so I am hopeful.

I used water to flush in both directions, and air at low pressure, then let bleach sit in the core for 1/2 hour, followed by water flush both directions, then air, and now its full of CLR for an hour.

Then water again, followed by fresh Pentosin, and a test drive to Muchas Gracias. If I don't get heat out of the core, I'll get it from the burrito.

Cheers
 
#16 ·
Until I viewed TOMVW's write-up on bleeding the cooling system, I did not know that there are two other places to bleed the v-6. I wonder if that is correct for North American Passats or just peculiar to the engines sold elsewhere in world? I, too, have tried bleeding my system after a heater core flush, at the passenger side heater hose, and I am getting heat from the heater core, but only so so at idle. At cruising speed it warms up more but not to the degree that I would expect, ~ 120 to 150 fahrenheit. If we do have two other places to bleed the system, can someone post the pics of exactly which hoses this applies to? Thanks a million.
 
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