Pump/strategy for heater core flush?

[Formerjeeper]

Need to thoroughly flush heater core on my 2005 truck that has seen some neglect (before I bought it). Had a shop do water pump, thermostat, etc. and they flushed radiator thoroughly but still seeing little or no heater core functionality.

First will run Thermocure through system: https://www.amazon.com/dp/B00R74I5UY/?tag=atomicindus08-20

Plan is to use this flush tool or something similar: https://www.jbtools.com/otc-6043-tool-multi-purpose-cleaning/

Would like to use distilled water only so I don't introduce any city water to system. Wondering if there's a way to get enough distilled water flow to make this work? If I fill a large bucket/small trashcan with distilled water, is there a submersible or electric transfer pump that will provide enough flow?

Guessing drill pump like this is insufficient: https://www.amazon.com/gp/product/B00F1ZJG5E/?tag=atomicindus08-20

Could also use gravity by putting the water tank on top of the truck?

Definitely open to better ideas for pump or method/process. Thanks.

 

[paulsomlo]

I don't know that vehicle, so pardon my ignorance - if you access the heater core connections at the firewall, can you pour in your flush liquid (funnel, gravity feed, etc.), then use a wet/dry vac to **** it out? I know that's not the same as blasting it out under pressure, but it might get the job done.

 

[FMB4]

You don't mention the miles on your truck. That said, first make double sure that the heater control valve is operating properly (I'm sure you've done so, but I wanted to mention it anyway). If control valve checks out OK, then try the above. That said, if your trk has over 200K on it then a replacement heater core might be the only answer.

 

[yatg]

Are your blend doors working properly? Known problem on 3rd gens.

 

[TobeyA]

I did this to my XJ Cherokee last year. A one way flush won't cut it. I had to flush one direction until it flowed clean. Then the other. Then repeat about a dozen times until it towed clean both ways. I used a radiator flush kit connection on both sides of the heater core.

I'd use the water hose to get it clean, then a final flush with distilled water if that concerns you.

 

[bayseven]

I have had good luck with running a long hose from core into a bucket of water and using wet vacuum on other hose gently sucking ( not air tight connection) it up and repeating in other direction.

 

[RTM]

Something like this may do the job. Not cheap to buy new, I got mine used. Put one end in your bucket of clean water, and pump away. Several GPM flow rate, can be slowed with smaller ID hoses. Very useful to have around during heavy rain.

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[PoorUB]

Many times I have just turned on the garden hose and held it to the heater core fittingss and blasted them out, flush from both sides. I don't think city water would be an issure, just blow it out with compressed air afterwards. The tiny bit of water left over won't amount to anything.

 

[2ndGearRubber]

I flush through either hose 5-6 times - put the nozzle in there and go wide open, alternating directions. 9/10 it's still clogged, but people get lucky from time to time. Just blast the hose until it pushes clear water out, then the other direction, etc.

 

[kelpaso1]

Many core plugs are caused by calcium build up inside the tubes. No amount of flushing works that great.

 

[Alienbaby17]

I see a lot of this type of work at this shop starting this time of year. In fact I just flushed a heater core a few days ago.

As others have suggested, first make sure the heater core is the culprit. You’ll want to check the temperature of the inlet and outlet hoses for the heater core. I use an infrared thermometer for this. (On the one I did earlier this week one hose was at 160 and the other was only at 90.)

I usually remove both hoses right at the heater core. I have a pair of three foot long bulk heater hose sections that I put onto the heater core. Then I grab the shop hose and jam it into the end of one and squeeze the trigger full blast for 10-30 seconds. I do this half a dozen times and then switch the shop hose to the other short section of hose and repeat the blasting process. I’ll probably do it two dozen times each way.

Once that’s done I repeat but with a slight change. After I blast the water through I give a blast of compressed air to push out the water. I repeat this many times both ways.

I’ve never seen any leakage or damage to a heater core from flushing like this and it almost always yields very successful results. I’ve never been afraid to flush one like this because it‘s usually a last attempt to fix something that would otherwise have to be replaced so there’s nothing to lose.

In one very plugged case we tried something I read about on a mechanic’s forum. It had us remove both heater hoses and pour some CLR directly into the heater core and let it sit in there overnight. We flushed it with water thoroughly the next day and it worked.

 

[TobeyA]

In one very plugged case we tried something I read about on a mechanic’s forum. It had us remove both heater hoses and pour some CLR directly into the heater core and let it sit in there overnight. We flushed it with water thoroughly the next day and it worked.

CLR is what I used in my Jeep. It was clogged with mostly rust. Let it sit a couple hours, then did the flushing as in my first post above. Very similar to how you did it.

 

[Ign]

I agree with the garden hose. Flushing in reverse of how coolant would flow in normal use seems to be key to why this works.....but yeah, ya gotta go both directions repeatedly for best results.

In the past when I haven't been aggressive enough I've seen heat reappear for a day or so, but then whatever you dislodged with reverse flow settles back and heat output diminishes.

 

[lilredex]

Disconect at the fire wall and hook up your garden hose (with fittings). It will come clean, done this many times on my old Dodge trucks. Blow out any leftover water if it bothers you.

 

[joshmodelskidoo]

Flush the coolant and run a system cleaner in it for a week or so then re flush. If it’s a dodge or jeep check your flap doors. I have a 3rd gen(2003) ram I got used and i have flushed, replaced the heater core twice and radiator several times for expansion. After a quality radiator and redoing the head gaskets this summer it finally seems to make good heat. It would get better for a couple weeks or a year then have issues. I also used dexcool since i had some and some Chryslers use dexcool I figured it was ok. It is NOT!! I now use the stuff that it calls for. There was also a rag stuffed into the heater box that I found the first time I started to mess with the heat

 

[mopar4u]

Try your chemicals if you wish. Get as much loose crud out as you can. After that ive had luck with driving with the input output hoses reversed for a while. Eventually switch them back.

 

[Wrench97]

Pull the heater hoses off fill the core with CLR and let it sit for an hour then flush using a normal water hose, not need for a pump.
This will work 25% of the time, the other 75% will need a core replacement.

 

[American Locomotive]

Just use a garden hose hooked directly to the core and flow it backwards. That's what I did on my LandCruiser, and it worked perfectly. Huge plug of nasty rusty water shot out. Reversed direction a few times and it was fixed after that.

All of those cooling system cleaners are caustic and will harm the aluminum most modern heater cores are made out of.

 

[BDT/NWMN]

I built a flushing system using a Simmer M40 utility pump, a coupe 10' heater hoses, and a shorter heater hose. Garden hose fittings were added to one end of each hose, and the pump. I use a regular bucket to draw flush solution from, and put the return hose in the same bucket. I "favor" flushing a heater core separately. On some vehicles where the heater hoses on the firewall are difficult to access; you may have to use the return hose near the water pump to flush the entire system at once. IF doing so; when finished using the pump to recirculate the flushing solution; open all the drain plugs on the engine and radiator. Uncouple the 10' hose from the utility pump outlet, and connect your garden hose those 10' heater hoses; first one, then the other. At this point: If you disfavor the city water; rather than rinse with the garden hose; close the system drain plugs, fill the bucket with distilled water, and reconnect the utility pump to rinse the system.. It may take a few rinse cycles, after which the system drain plugs are again opened.

 

[demarpaint]

I have had great luck with problematic heater cores doing a citric acid flush of the cooling system, then disconnecting the heater hoses and flushing the heater core with a garden hose. Lots of good info on the web on citric acid flushing a cooling system. I found it to work very well.