How do you clean heater cores?

[whitedog]

We have a couple of buses, one with 780,000 miles and one with 817,000 miles and after all those miles, it seems that the heater cores in the passenger area have become plugged, or at least coated internally. I tried flushing the system with CLR and I got out a bit of scale, but not much.

Does anyone have any other suggestions on how to clean these out?

 

[El Dobro]

Have you tried this? It worked great on my Cadillacs where the pellets you use in them clogged the heater cores.
http://www.homedepot.com/p/Prestone-22-oz-Radiator-Flush-and-Cleaner-AS105Y/205011753

 

[Wankel7]

Interesting....CLR restored the heat on my 2000 Audi.

I disconnected both the inlet and the outlet. I filled the heater core wity hot water and a lot of CLR. Then I used a drill pump to circulate the solution for a few minutes.

 

[whitedog]

Maybe because this heater core has had 780,000 miles of coolant passing through it, it is more clogged up than the Audi? Maybe more calcified blockage?

 

[Honeydew]

You could try the citric acid powder flush, I got some at the local chain drug store. Here is a link the old Benz how-to: http://dieselgiant.com/mercedes_citrus_flush.htm

 

[whitedog]

Well, I have done the best I can with this one. I filled it with CLR and ran the drill pump one way then ran it the other way then let it sit for an hour or so and ran the pump again. I then used my big air gun and blew out the CLR then flushed it with water for awhile and blew it out again and flushed it and blew it.

I didn't get out hardly any solids so either it's clean or it can't be cleaned. The thing is that our water isn't very hard and it doesn't form much in the way of solid deposits. But it's as clean as I can get it right now. Now I'm waiting on tires so I can get it on the ground and take it for a good test drive.

 

[meerschm]

what does the plumbing loop look like?

are all the heater cores in series, or is there a branch someplace, perhaps with a control?

 

[whitedog]

It wasn't a plumbing problem since it's been plumbed this was since day one. I guess I got it cleaned out though. I took her for a drive and got her hot and now that heater puts out more heat with the fan off than it did before with the fan on. Seriously.

For reference though it is plumbed in series with a booster pump in there. The booster pump is good because I have to change them every 200,000 miles since they leak.

Thanks for everyone's suggestions. Now I have more ideas if I ever run into troubles.

 

[Fix_Until_Broke]

See if you can get ahold of a product called drycid.

https://www.chemetallna.com/products/by_app/cleanersInProcess.aspx

Scroll down about 2/3's of the way down, it's the first in the "Acid's". You may have to give an e-mail address to get the info (or PM me your e-mail and I'll send you some .pdf's).

It's a salfamic acid which specifically targets lime/scale buildup and not brass/copper/etc.

Works wonders on our process heat exchangers at work - we've got a 330 gallon plastic tote with a sump pump in it and circulate it overnight. Goes from a trickle to full sump pump flow in a few hours. The solution is all used up when the PH changes (specs in the data sheet)

CLR is similar stuff, but not as good. Part of the success is time and flow rate. You need to constantly flow the solution through the scaled up areas so it can be more effective and carry out the dissolved scale. It takes hours (overnight).

 

[whitedog]

Our water here isn't very hard, so we don't get alot of build-up so I don't think that we need to get out the big guns. On bus#2, I am going to try vinegar. That's what the guy at the radiator shop suggested.

 

[MPBsr]

I've used this in the past with other cars.

Forces the water to reverse the flow and you'd be shocked when you see the garbage come out of the core.

http://www.amazon.com/Prestone-AF-K...8414048&sr=8-1&keywords=heater+core+flush+kit

 

[whitedog]

I've used this in the past with other cars.

Forces the water to reverse the flow and you'd be shocked when you see the garbage come out of the core.

http://www.amazon.com/Prestone-AF-K...8414048&sr=8-1&keywords=heater+core+flush+kit

Thanks for the suggestion. I don't have a problem with hooking up to the heater core. I think that I was overly worried about getting the inside clean and breaking loose the scale inside. "Overly worried" because it's kickin' out the heat now.