A few years ago my Jeep Wrangler heating was luke warm during the winter. I poked around under the hood, and replaced the thermostat since it was easy to do, but no joy.
I just put up with shivering, but then one day the temperature gauge climbed a bit and it smelled “hot”, so I stopped at my car guy’s place. He said my heater core was blocked. He flushed it and I had heat again!!! IIRC he charged me $80.
Thing is, I’d never heard of a heater core.
Maybe 9 months later the problem returned. I can do simple repairs (brakes, oil changes, even ball joints back in the day), so I looked on YouTube and flushing the heater core seemed simple. I bought hose and fittings and did a quick flush. The bucket I used had stuff in it, so I couldn’t tell if anything was dislodged.
Everything was back to normal for a few months, then the problem returned. This time I spent more time flushing, and did it through both hoses several times. All has been well since then.
What can I expect now? Can I just flush every time this recurs? Heater core replacement is out of my league and the Jeep has 120,000 miles. Time to trade?
Heater core problems can be potenitally catastrophic. Well, maybe thats a bit extreme. But they can develop leaks that can cause the vehicle to lose its coolant very quickly. I had one that had a sudden “leak” that poured coolant out and emptied the engine completely in less than 30 seconds. Adding to the fun was the fact that the heater core was tucked into the dash above the glove box, so alllllll that coolant ended up in the passenger compartment footwell. Fun times! Good thing I had an upholstery shampooer at home.
Usually they either a) get gummed up like yours is doing or b) develop a pinhole leak and you’ll start finding puddles of coolant in weird places (like inside the cab) or the windshield will fog up even with the defroster on – sometimes especially with the defroster on.
So my recommendation, from someone who’s not in any way a mechanic but who’s been there, is to replace the heater core. I couldn’t tell you if that’s a DIY job although it’s something I would pay to have done just because they’re usually buried behind the firewall somewhere and are a PITA to remove. If you go that route, have the radiator flushed at the same time.
As you’ve also learned a failing heater core can cause your engine to overheat which is always a bad situation. Best to get that taken care of sooner rather than later especially if you’re driving in the summer.
Finally, assuming you take good care of your rig and don’t abuse it and have done all the recommended maintenance on it, 120K miles is barely middle-aged. A failing heater core is common and personally would not be a reason to trade in the vehicle.
This is odd, I spent nearly my entire life as a mechanic and never flushed a heater core. I have to wonder if some kind of chemical reaction may be producing a sludge?? Did you flush the entire system and use the recommended coolant?
I am surprised you never had heard of a heater core, or that others have not heard of them getting clogged. They are a crucial item for Canadian drivers, and this is a common problem.
The typical mechanics approach is to replace it if you really want to fix it. Every now and then we have to replace one on one of the trucks at work. It can be pretty labour intensive. Flushing may not clean it out sufficiently, especially if it is due to scale.
There was a descaling product I ran through one of my old beaters when I was young thay sermed to fix the problem.
What year? There was a run of Jeeps that had issues with rust in the cooling system then those flakes blocking the core. Guess how I know. If it is that, then you would need to flush the whole system which is an expensive pain.
Your whole cooling system needs a flush, not just the heater core. I would also perform coolant changes much more often if your cooling system plugs the heater core that quick.
The heater core is like a little radiator. Coolant flows in from the engine, through the core, then back out to the engine. The core is behind the dash and can be quite a bugger to change and may need to remove the dash. The more common failure is for it to spring a leak and put coolant inside the car, fogging up the windows. The Jeep may be easier to change.
Not really a job that I would do myself without a lot of pateince and available vehicle down time. And I do almost everything myself on my car.
I have a 2000 F150 that the previous owner abused by not fixing a coolant leak, and simply adding water to the radiator. That rusted the coolant jacket, and clogged the radiator and the heater core. I was able to unclog the heater core by flushing it backwards. And I replaced the radiator. I ended up using Evapo-rust, which probably helped get rid of some of the rust, but the only thing that really worked was an in-line filter, which catches all the tiny rust flakes that otherwise would end up clogging something.
It is part of the whole coolant system flow, not separate from the engine. The same coolant flowing through the main radiator and the engine also flows through the heater core. No flow, no cooling the engine. If the heater core is plugged it is like a radiator hose being pinched.
If you have some kind of over-heating problem with an engine, and the heater core is working fine, you can turn the heater on high and the fan up and that will help cool the engine while you try to get home. Like an extra little radiator. Good to know in an emergency.
I once owned a 1997 GMC Safari van. The heater core started leaking. I didn’t want to tear apart the dash (which I believe is the proper procedure), so I cut away the plastic panel from inside the engine compartment. The heater core was then easy to get to. I replaced the heater core and epoxied the panel back in.
