Heater Core Cleaning Options
- Thread starter geogixxer
- Start date
I would do the garden hose back flush first. Maybe do the radiator at the same time.
Not sure. Dealerships may be topping off with tap water?
I've tried to research this but haven't found anything. My guess is that G48 produces a protective film which plates out when the coolant ages and this residue builds up in the heater core. The heater cores also employ a parallel design which allows for build up to settle out in the section which experiences the lowest amount of circulation (furthest from the input/output). My wild guess. We'll see, I'm supposed to bring my car to a shop tomorrow. I fear they're not going to flush the core and end up recommending that I fire the parts cannon. 5yrs I'm trying to convince my wife that I need to get this done even though I haven't been driving the car as much.
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I did our 10 year old truck this winter. My fear was being TOO aggressive upfront and eating away unnecessarily at the heater core. Mine was not completely clogged. Better to progressively get more assertive. Don't start with drano or 6 hour hot pump sessions with straight CLR.
I had good luck with alternating between garden hose and compressed air in both directions. Then I poured CLR in using a funnel and let it sit for 15 minutes. Then thoroughly flushed with water and air before reconnecting. I didn't buy any fancy tools. I used a short segment of broken off garden hose and used a piece of 1/2" pex as a coupler to slide into one heater hose, then the other. Measurably greater heat output was the result. Greater than factory specification. Based on that I then (a month later) did a flush then citric acid clean of the entire system, multiple flushes, new water pump, new (better) coolant.
Starting out I had ~110 F degree register air (blower on full, engine at operating temp, 1000 RPM) with 35 degree outside ambient. After, it's more like 145 F.
To be clear, my core flowed water, so I do not believe either air hose or water hose produced significant pressure within the core. Yet, I believe some pressure (blasting the water out with compressed air) helped to break and clear any buildup.
I speculate that in general, 10 years is too much to ask of some of the modern miracle coolants. Incompatible coolant top-offs complicate this. Silicate fall-out complicates this. Nitrate-Borate-2EHA whatever complicates this. Controlled acid braising, etc. Better to be proactive. Easy DIY. If system hasn't been drained in 5 years (busted hose, radiator, water pump, etc) then it gets, at a minimum, a drain and fill. Not expensive. Not time consuming. Cars with unknown history get as much of a flush effort as I can manage.
I had good luck with alternating between garden hose and compressed air in both directions. Then I poured CLR in using a funnel and let it sit for 15 minutes. Then thoroughly flushed with water and air before reconnecting. I didn't buy any fancy tools. I used a short segment of broken off garden hose and used a piece of 1/2" pex as a coupler to slide into one heater hose, then the other. Measurably greater heat output was the result. Greater than factory specification. Based on that I then (a month later) did a flush then citric acid clean of the entire system, multiple flushes, new water pump, new (better) coolant.
Starting out I had ~110 F degree register air (blower on full, engine at operating temp, 1000 RPM) with 35 degree outside ambient. After, it's more like 145 F.
To be clear, my core flowed water, so I do not believe either air hose or water hose produced significant pressure within the core. Yet, I believe some pressure (blasting the water out with compressed air) helped to break and clear any buildup.
I speculate that in general, 10 years is too much to ask of some of the modern miracle coolants. Incompatible coolant top-offs complicate this. Silicate fall-out complicates this. Nitrate-Borate-2EHA whatever complicates this. Controlled acid braising, etc. Better to be proactive. Easy DIY. If system hasn't been drained in 5 years (busted hose, radiator, water pump, etc) then it gets, at a minimum, a drain and fill. Not expensive. Not time consuming. Cars with unknown history get as much of a flush effort as I can manage.
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Be careful with garden hose pressures. This method can cause leaks, as water pressure is generally higher than rated cooling system max designed pressures. I would recommend a funnel and gravity draining, or very low pressure electric pump usage.
A word of caution about the off the shelf cleaners - some have sodium hydroxide as an ingredient which would be corrosive to an aluminum heater core.
CLR Has a specific chemical for this now.
https://www.clrbrands.com/proline/products/clr-pro/clr-pro-heavy-duty-radiator-flush-and-cleaner/
https://www.clrbrands.com/proline/products/clr-pro/clr-pro-heavy-duty-radiator-flush-and-cleaner/
I once read somewhere that Honda tried some kind of inner lining to increase the life of those heater cores, but that lining comes off and cloggs the passages.
The CLR pumping does remove the problem material.
Keep in mind, that for most chemical reactions, the rate of reaction doubles for every increase of 10 degree C, ( or 18 degree F ). A cheep pump probably has a rubber impaller, so too hot CLR might damage the pump.
Ya want it hot, but not super hot.
The CLR pumping does remove the problem material.
Keep in mind, that for most chemical reactions, the rate of reaction doubles for every increase of 10 degree C, ( or 18 degree F ). A cheep pump probably has a rubber impaller, so too hot CLR might damage the pump.
Ya want it hot, but not super hot.
I take it the “ factory fix” is to establish a continuous circulation loop rather than a single pass? A high flow rate aquarium pump might work. JB Marine might be good to help seal hoses used to rig things up. You could dump into a large bucket to let things settle out and draw from the top of the bucket for the return pass. Going in the backflow direction might help. Let us know if it worked.
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