The best way to flush your heater core

[Garf]

Well, today was cold and just when I needed some heat , and it was blowing cold air.


What is the best solution to flush out the heater core?. Some say CLR , then some say it is not effective enough. One guy says Muriatic acid.

The upper hose has an air bleed hole in it. I am assuming that is the input line. And for me to flush the heater core, I need to pump the crude out through hose below it?????

What does a Audi dealer do to flush your heater core?

[seanf86]

I use a garden hose and alternate back and forth between inlet and outlet, mine was plugged up so bad I'd have heat for a little while and back to no heat, ended up just replacing the core.

[Preston_08]

Well, today was cold and just when I needed some heat , and it was blowing cold air.


What is the best solution to flush out the heater core?. Some say CLR , then some say it is not effective enough. One guy says Muriatic acid.

The upper hose has an air bleed hole in it. I am assuming that is the input line. And for me to flush the heater core, I need to pump the crude out through hose below it?????

What does a Audi dealer do to flush your heater core?

Bought a core for my previous and current B6 at autozone, easiest way to go IMO,


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[Tongpo]

I recommend you replace the core. I discovered my core was plugged last Fall. Had it flushed at an independent Audi shop and had good heat for a few months, then it plugged again. I lived with bad/no heat for the last month of the 2014/2015 winter - not pleasant. I replaced the core a few weeks ago and now have great heat.


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[SJorge3442]

Plenty of guys run CLR through the core using a pump. This is what I would do. I don't want to have to hang out upside down and do a heater core replacement if I dont need to!

[old guy]

Clicky click®

[Ian1006]

Just did mine a couple weeks ago using old guys post as a guide. Got hot heat back for maybe a month, just noticed two days ago it's only warm now :( going to back flush again and if it goes to warm after that I'll replace mine. It's easy to back flush though, and having hot hot heat was worth the effort but not if I have to do it every month or two.

[Johann2.7t]

just buy a new one, flushing mine was ineffective.

[Garf]

"Old Guy", thanks for your link. I will certainly do the flush and if the heat comes back I will be very happy. If it doesn't then I guess the heater core is toast. What is the "gph" rating on your pump? I found a few bilge pumps, 200gph, 1000gph and 2000gph. I heard the core can not take more than 10psi going into it.

I don't understand your issue "Ian1006". Flushing the heater core is a mechanical process. If it is cleaned and allows the coolant to flow through it giving you heat. If you loose it again in a few months, then debris or crude is clogging it again. That is a separate issue then.

Anyways, a heater core is cheap, but the paying a shop to do it for me is not cheap at all. I also don't want to do it myself after seeing how disassembling that has be done to your dash and surrounding interior components.

[Tongpo]

On a B6, you don't need to disassemble the dash to replace the heater core. Do a search here on AZ and you'll find a good thread on this.

[old guy]

Anyways, a heater core is cheap, but the paying a shop to do it for me is not cheap at all. I also don't want to do it myself after seeing how disassembling that has be done to your dash and surrounding interior components.

Flushing it is pretty easy. but if you do go to replace the heater core the procedure isn't too bad. I suspect you may have viewed a DIY for the B5. That is a horrendous process. The B6 is fairly straightforward. Clicky click®

[Garf]

Flushing it is pretty easy. but if you do go to replace the heater core the procedure isn't too bad. I suspect you may have viewed a DIY for the B5. That is a horrendous process. The B6 is fairly straightforward. Clicky click®

I rather not do any replacement if possible. I am surprised how much easier the B6 is to remove the heater core!

I did have heat a few weeks ago, so it may be savageable at this point with a flush.

[EuroxS4]

b6 heatercore slides right out.Cake an hour tops to do.Dont make a mess!!I remove hoses at the cowl plenum.Blow compressed air through the core.That way when you remove the lines inside the car you dont have coolant floating on your carpet.LOL.Hands down just replace the heater core they are cheap now.Maybe $60 for a oem one.


Ive heard of people using clr,white vinegar and cirtric acid at a high temp.I believe MB sells a jar or citric acid powder you mix with water then boil.

[Ian1006]

I have drained coolant twice completely and back flushed my heater core until I got hot heat. I still have heat but not the same as before so that is why I am doing it again. If it fades again I'll replace it

[Garf]

b6 heatercore slides right out.Cake an hour tops to do.Dont make a mess!!I remove hoses at the cowl plenum.Blow compressed air through the core.That way when you remove the lines inside the car you dont have coolant floating on your carpet.LOL.Hands down just replace the heater core they are cheap now.Maybe $60 for a oem one.


Ive heard of people using clr,white vinegar and cirtric acid at a high temp.I believe MB sells a jar or citric acid powder you mix with water then boil.

Which is the most effective, .... CLR, citric acid or Prestone?

Hey, "Old Guy", I am picking up the bilge pump tomorrow. Should I get a 500GPH, 800GPH, 1000GPH or higher?

[A4orce84]

What's ballpark for a replacement heater core?

Thanks,
Asif

[old guy]

Which is the most effective, .... CLR, citric acid or Prestone?

Hey, "Old Guy", I am picking up the bilge pump tomorrow. Should I get a 500GPH, 800GPH, 1000GPH or higher?

500 GPH should be more than adequate. I have had good luck with the Prestone flush. That is what it's made for. Why not use it?

[old guy]

What's ballpark for a replacement heater core?

Thanks,
Asif

Aftermarket 50 to $75. OEM $185.

[jacobsen]

I guess I'm mr. Danger. The muriatic acid in my opinion is the way to go. It's a bit intimidating but if you have the hoses hooked up right and you circulate it back and forth 10 minutes in either direction your core will be brand-new inside. Folks who have recurrence of clogging probably have a lot of crap built up in your cooling system which is getting trapped in the centrifugal inserts of the heater core. So flushing the coolant multiple times over the course of the week can give you a good idea just how much crap you're getting out by simply draining it. I used a 1/4 horsepower sump pump. Afterwards I flushed it like crazy with like 10 gallons of distilled water. What's better distilled or deionized? If you did replace your heater core make sure you replace it with a metal end cap core not plastic end cap. My heat blows two years after doing the muriatic acid flush at 180 degrees. It's downright uncomfortable, the way it should be. True Minnesota just don't like the Heat.

And as always never tried to burp air out of the cooling system with the motor running. You must absolutely make sure that the motor is cold and not under any thermal pressure at all. All you have to do is fill the expansion tank and you can lift it up high if you choose to Kama that can make it go a little bit faster. Open the top heater core hose with a little hole on it until it works out its air and run study coolant. Same procedure for the coolant hard pipe bleeder.
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[Ian1006]

I have used radiator flush treatment, simple green, a degreaser and did about 3-4 water flushes this weekend. Funny is that each time I drained and refilled my bucket there was about 1/2 tablespoon to a teaspoon of grit each time, I did this until no grit came out. I need to bleed air another time or two still and see where I end up with the heat. If this doesn't do it I'm doing a heater core soon and a flush of the entire engine. I have seen inline heater core filters for about 50 bucks which might be nice to protect the investment...

[jacobsen]

I have used radiator flush treatment, simple green, a degreaser and did about 3-4 water flushes this weekend. Funny is that each time I drained and refilled my bucket there was about 1/2 tablespoon to a teaspoon of grit each time, I did this until no grit came out. I need to bleed air another time or two still and see where I end up with the heat. If this doesn't do it I'm doing a heater core soon and a flush of the entire engine. I have seen inline heater core filters for about 50 bucks which might be nice to protect the investment...

The inline filter is a good idea. I looked into this as well. You will need to plumb it right. Which will take a little bit of effort... But it is doable. Degreasers will not remove any of the silt, mineral scale or dried up crusty stuff. You really should use something like Zep drain cleaner at the very least. It has the acidic power to do the trick if you let it sit long enough. But like I said the acid and gets the job done there and then. You just want to make sure that you flush the system several times before you do it and make sure you're just flushing the heater core not the entire cooling system with the acid.

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[customa4]

Looks like Europa has OEM on sale. Click