84-85 Trucks & 4Runners 2nd gen pickups and 1st gen 4Runners with solid front axles

heater core flush?

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Old 12-06-2008, 01:18 PM
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heater core flush?

Can someone confirm this is all correct before I start tearing things apart?

I'm guessing this is the outlet of the heater core



This must be the inlet and the metal piece in between the hoses is the heat valve?



I'm also guessing this where I should disconnect the outlet hose for the flush



And this where I disconnect the inlet hose for the flush



I must have the heat valve open to do the flush and use low pressure when doing it and alternate sides inlet outlet until the water flows clear and fluently though.

Is there anything else I should need to know?
Old 12-06-2008, 03:08 PM
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Well. I went ahead and did it... To my surprise there wasn't anything clogging the heater core. there are no leaks or smell of anti freeze in the cab. Any ideas on how to improve my heater? or fix it
Old 12-06-2008, 09:03 PM
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Wow, sorry to hear that that didn't do anything for your heat. I just flushed mine today, very fun in December in Colorado playing with water outside, and I now have the hottest heat ever. Did you flush it like 4 times in each direction? Did you use enough pressure?
Old 12-07-2008, 12:10 AM
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I just pulled the inlet and outlets off... at the valve and at the firewall as you have you in your pictures..

took the garden hose with an oldschool spray nozzle. Full blast, blasted the effer clean. worked flawlessly, heat went from 0% to 100%.

you mentioned low pressure, why? Just blast water through the son of a gun
Old 12-07-2008, 04:22 PM
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I had read somewhere that the low pressure was recommended because it could cause the core to spring a leak if you used a higher pressure.

I also have another guy say that he used lime a way and let it sit in there for about ten minutes and then flushed her clean and all sorts of stuff came out. Any suggestions on this. I bought some and am going to give it a try in about an hour or so.
Old 12-17-2008, 12:45 PM
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So now I'm confused...I was always under the impression the heater core was in the engine bay.

I've seen a writeup on removing the heater core, and it involved tearing apart the dash. This, along with seeing various other posts here on the forums refer to the core being under the dash.

Was I thinking of the wrong part the entire time? Is the heater core in the engine bay? The little egg shaped ball with the hoses going into the top and out of the bottom?
Old 12-17-2008, 12:51 PM
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The heater core is inside the cab under the dash. The hoses go through the firewall
Old 12-17-2008, 06:58 PM
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is it possible to flush the core with it still in the dash? hook a garden hose to one hose going to the core?
Old 12-17-2008, 07:28 PM
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that's exactly it. You disconnect both sides and flush the heck outta it. Use decent pressure. If that doesn't work then you can use some lime a way and let it sit for 10-20 minutes in the heater core and then flush it w/some decent pressure.

Also make sure it isn't your heater valve that's causing your heater to not work.

If that doesn't work, make sure it isn't your thermostat too.

If after those three things it still doesn't work then you are outta luck and need a new heater core. Best of luck to ya and if you have any questions about it go ahead and post and I will help ya out more.
Old 12-17-2008, 07:38 PM
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want to be totally sure its flushed, flush it and back flush it, flush one end til the water runs clear, then do the other side til it runs clear, then back to the first side, and so on, do that for half an hour. i almost guarentee that will fix it. thats what i did with mine, and i did that a year ago and its still blowin super hot. not as hot as then, but still pretty hot.
Old 12-18-2008, 10:24 AM
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Originally Posted by live4soccer7
I had read somewhere that the low pressure was recommended because it could cause the core to spring a leak if you used a higher pressure.

I also have another guy say that he used lime a way and let it sit in there for about ten minutes and then flushed her clean and all sorts of stuff came out. Any suggestions on this. I bought some and am going to give it a try in about an hour or so.
Yeah, I used very high pressure and had a pool of water in my passenger floor area. Be careful. No leaks with normal running pressure, luckilly.
Old 12-18-2008, 01:18 PM
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I flushed mine with the hose on full blast. Although I wouldnt suggest using a pressure washer or anything like that
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