Front & Rear Heater Core Flush

[cmatt]

I’m changing fluids in my new to me 135k mile 2012 Suburban and the coolant is next. While doing so, I thought it might make sense to flush both heater cores. I haven’t seen much info on flushing the rear one. Is there anything I need to be mindful of?


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[Derick]

Curious to know too. I plan on doing a cooling system hardening myself within a few months. I know I'm going to backwash the heater core.. But curious to hear the word on the rear unit as well.

 

[gooffeyguy]

I've never really heard of anyone having problems with a clogged rear heater core. I guess it wouldn't hurt anything to do it.

I had a problem with my 2001 about a year ago with the front not putting out heat and I back flushed it and it fixed it. Never had a problem with the rear. The truck has 215k on it and original cores

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[Fless]

Just watch the water pressure, keep it fairly low to start with until you are sure you have good flow. Full house water pressure (60+ psi) could be too much for the system (15 psi), since water doesn't compress easily and that can be ******* connections. Have an extra short hose to redirect the outflow.

 

[gooffeyguy]

Good point.

When I did mine, I have a ball valve type of fitting on the end of my garden hose and I only cracked it open a bit, not even half way.

Looks like this, Lowes, Home Depot, etc about $7

 

[cmatt]

Kind of related, but it makes me want to disassemble and clean my rear HVAC box.

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[exp500]

Good call on the water pressure Fless! That could turn into a whole nother can o worms.