Yet Another Clogged Heater Core

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Brewer

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Have the common heater core issue that I see many others have struggled with. This summer took my 2016 2500 (cummins) in for a coolant flush and replace. Come fall when goto use heater, it's only luke warm. Take it in and they flushed the core. Heat GTG for a few days before back to luke warm.

It sounds like it can take 3 or more flushes to clear these things. Before I spring for the full core replacement (they quoted 1600 bucks) I'm thinking I should probably have them flush it again.

Any special instructions/requests I should make regarding the flush in terms of how they go about doing it? How many times should I give the flushing a go before I just suck it up and pay for a core replacement.

Thanks!
 

Wild one

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TMyers

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I flushed mine three times. The first two times I did it with the water hose and an air compressor. The last time, I pulled both lines and rented a submersible pump and did a mixture of hot water and radiator cleaner in a tub. I put the pump in a pillowcase and ran it both directions for over 5 hours. Most of what I found was sand in the bottom of the tub. I assume it was casing sand from the block casting process. It helped tremendously and I had heat. That was last winter. This winter I smelled antifreeze in the cab and had to change out my heater core.
 

nlambert182

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Have the common heater core issue that I see many others have struggled with. This summer took my 2016 2500 (cummins) in for a coolant flush and replace. Come fall when goto use heater, it's only luke warm. Take it in and they flushed the core. Heat GTG for a few days before back to luke warm.

It sounds like it can take 3 or more flushes to clear these things. Before I spring for the full core replacement (they quoted 1600 bucks) I'm thinking I should probably have them flush it again.

Any special instructions/requests I should make regarding the flush in terms of how they go about doing it? How many times should I give the flushing a go before I just suck it up and pay for a core replacement.

Thanks!
Simple suggestion... do it yourself. It's really simple to do and you can control how long you flush it. If they get heat immediately they may stop but if there is still casting sand in there it will settle eventually. I flushed mine twice and the second time was for almost an hour straight. That seemed to do the trick. I also used CLR but there are some dangers with doing that and I won't recommend it unless you are prepared to buy a replacement core if it fails.
 

mtnrider

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I have flushed mine many time over the past couple of years. At the beginning of every winter I would have to do it a few times to get it working consistently, then not using it all summer it would clog up again and I would do the same the next year.
This year I did a full cooling system flush (it was time to change it out anyway), ran it a couple days with distilled water, flushed and repeated. Then tried to force all the water out through the radiator drain at the bottom (using air). It has been working great so far this winter so hopefully I got the last of the crap out of there.

Eventually I may have to drop the dash and replace it but at this point I've been able to keep it working and with the air assist gun and hose setup I made it doesn't take me long to flush the core again if needed.

The other option is to put a inline filter on the heater core input line which I may do as well. Try and trap the gunk before it get's in there.

.

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Brewer

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I have flushed mine many time over the past couple of years. At the beginning of every winter I would have to do it a few times to get it working consistently, then not using it all summer it would clog up again and I would do the same the next year.
This year I did a full cooling system flush (it was time to change it out anyway), ran it a couple days with distilled water, flushed and repeated. Then tried to force all the water out through the radiator drain at the bottom (using air). It has been working great so far this winter so hopefully I got the last of the crap out of there.

Eventually I may have to drop the dash and replace it but at this point I've been able to keep it working and with the air assist gun and hose setup I made it doesn't take me long to flush the core again if needed.

The other option is to put a inline filter on the heater core input line which I may do as well. Try and trap the gunk before it get's in there.

.

.
Can you share details on your air assist gun and hose setup?
 

mtnrider

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Can you share details on your air assist gun and hose setup?

Here is a great video showing pretty much what I do.


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Brewer

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Here is a great video showing pretty much what I do.


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so you bought that gun he's using then? sounded like you had made your own.
 

mtnrider

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so you bought that gun he's using then? sounded like you had made your own.

Yes, bought the gun. I just have a system (routine) for how I flush it. Got hose's all setup and everything ready so it's a easy job.
 

stevewithavision

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Have the common heater core issue that I see many others have struggled with. This summer took my 2016 2500 (cummins) in for a coolant flush and replace. Come fall when goto use heater, it's only luke warm. Take it in and they flushed the core. Heat GTG for a few days before back to luke warm.

It sounds like it can take 3 or more flushes to clear these things. Before I spring for the full core replacement (they quoted 1600 bucks) I'm thinking I should probably have them flush it again.

Any special instructions/requests I should make regarding the flush in terms of how they go about doing it? How many times should I give the flushing a go before I just suck it up and pay for a core replacement.

Thanks!
I had a lukewarm heater also on mine, I replaced the damper motor door controller, helped a lot. It is behind the glove box with one plug held in place by two Phillips screws. I bought a doorman product for just under $20 delivered on Amazon. Hope this helps.
 

slbenz600

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Have the common heater core issue that I see many others have struggled with. This summer took my 2016 2500 (cummins) in for a coolant flush and replace. Come fall when goto use heater, it's only luke warm. Take it in and they flushed the core. Heat GTG for a few days before back to luke warm.

It sounds like it can take 3 or more flushes to clear these things. Before I spring for the full core replacement (they quoted 1600 bucks) I'm thinking I should probably have them flush it again.

Any special instructions/requests I should make regarding the flush in terms of how they go about doing it? How many times should I give the flushing a go before I just suck it up and pay for a core replacement.

Thanks!
I am unsure why the coolant system needs to be flushed more than once if it's done right ? My 2015 had no heat I took to a machanic that deals with all kinds gas and diesel. It sounds like for some reason RAM never flushed out the block before assembly may take a little extra work. I would suggest taking your cummins to a diesel shop they deal with cummins in big rigs all the time, they may have to pop out freeze plugs and flush the block. I have a friend that owns a diesel shop he told me one of the problems with antifreeze is people allow the PH level to drop that will allow corosion in the block and radiator. Diesel shops sell PH supplement plus the test strips to test annually that is the cheapest maintenance that anyone can do to prevent thousands of dollars in repairs. Just food for thought not saying this will fix your truck but it fixed mine. If you can get RAM to fix your truck thats great but if your stuck with repairing take it to someone that works on them every day. Good luck?
 

nlambert182

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It can be difficult to get the casting sand out of the core on the first attempt, but with some patience it can be done. I think a lot of folks fail on the first try (like me) because they try to rush the process.

There's no reason to take it to a dealer and spend $500-$1000 to flush the core when you can do it at home for almost free. This is not an antifreeze problem and not a complete cooling system problem... it's a casting sand problem specific to the heater core. Yes, it's wise to flush the cooling system periodically, but assuming the coolant still meets the spec it's much more economical to just flush the heater core.
 

Joseph Godvin

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Bad heater core design, they operate like a radiator, tank on top and bottom. hard to back flush. Old design used a continuous tube that winded from inlet pipe to outlet pipe, whereas it could be back flushed easily. tubes in the new one get clogged farthest from the inlet and outlet, next to impossible to fully remove debris in those tubes. I have changed several and cut them in half to see what has plugged.
 

truck2569

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Have the common heater core issue that I see many others have struggled with. This summer took my 2016 2500 (cummins) in for a coolant flush and replace. Come fall when goto use heater, it's only luke warm. Take it in and they flushed the core. Heat GTG for a few days before back to luke warm.

It sounds like it can take 3 or more flushes to clear these things. Before I spring for the full core replacement (they quoted 1600 bucks) I'm thinking I should probably have them flush it again.

Any special instructions/requests I should make regarding the flush in terms of how they go about doing it? How many times should I give the flushing a go before I just suck it up and pay for a core replacement.

Thanks!
It should only take one flush sometimes two depending how dirty it was the first time. What I did was disconnect my heater hoses and flush it from there till I got clean water running. I usually flush my system every 3 years and add new coolant. I have a 2013 1 ton some people think I'm nuts but I don't have a large repair bill either and I have 587,000 miles on my truck.
 
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