LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Heater Core Flush

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Old Nov 2, 2008 | 02:11 PM
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Default Heater Core Flush

A few weeks back when the weather turned cold I noticed that my heat wasn't blowing like it should so I figured I'd flush the heater core.

I never honestly knew it would make that big of a difference and it's so easy. It's amazing what that little amount of gunk can do to the cooling system.

If anybody is having this problem don't hesitate to try and flush your heater core -- its simple and makes a huge difference.

Figured I'd just post this for the guys who are scratching their heads about their heating problems. Try this first!!
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Old Nov 2, 2008 | 02:45 PM
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Yeah it does make a big differance!!!!
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Old Nov 2, 2008 | 02:51 PM
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Originally Posted by TDavanzo
A few weeks back when the weather turned cold I noticed that my heat wasn't blowing like it should so I figured I'd flush the heater core.

I never honestly knew it would make that big of a difference and it's so easy. It's amazing what that little amount of gunk can do to the cooling system.

If anybody is having this problem don't hesitate to try and flush your heater core -- its simple and makes a huge difference.

Figured I'd just post this for the guys who are scratching their heads about their heating problems. Try this first!!

Hey mine does the same lol help how do you flush the heater core lol please...
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Old Nov 2, 2008 | 04:54 PM
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ya how do you do it....im about to swap my 160* tstat for a 180 for these winter months also
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Old Nov 2, 2008 | 06:04 PM
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All I ever do is take the heater hoses off at the water pump and run water through it with the garden hose in both directions. I did it to my car last week and it brought all my heat back.
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Old Nov 2, 2008 | 07:07 PM
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The way I did it today was take the hoses off the firewall. It's a good idea to have some spare heater hose laying around so you can re-direct coolant.

Fergymotos way eliminates the need for re-direct hoses.

I took my lines off at the firewall (to the right of your a/c hookups)

One is bigger then the other but basically you take both hoses off, put your extra hose on the opposite connection your going to blow through. Then take your garden hose and put it directly onto the open connection and flush! You should see dirty coolant and possibly some gunk come out.

Now in my situation I was lucky enough to have two extra hoses so I put the garden hose nozzle into an additional hose which eliminated any and all coolant/water getting onto the motor or wiring.

This brought the heat back immediately. It's just a band aid though, if your core got gunked up then that **** is still circulating in your coolant system. Its a good idea to have it flushed whenever you have to 70-100 bucks laying around but this will work short-term and is an easy free fix.
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Old Nov 2, 2008 | 11:52 PM
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good to know doin this on tues
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Old Nov 3, 2008 | 12:52 AM
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when my heat doesnt work i sure as hell wont be flushing my system!!! haha...im puttin a new damn heater core in because my luck in the middle of the winter the thing will go out on me on one of those cold *** indiana days where its like 10 degrees and im 4 hours from home...haha....good luck though guys!!
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Old Nov 3, 2008 | 04:33 AM
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pics if u could .....that way i dont mess up
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Old Nov 3, 2008 | 04:24 PM
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To the kid who replaces his heater core instead of flushing it. Hopefully you are flushing the system when you're replacing the core otherwise you're going to gunk your new one right back up.

I don't have my digital camera at my apartment. If you take a picture of your engine compartment focusing on your air conditioning hookups towards the firewall I can use photo editing software to show you right where it's all at.
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Old Nov 4, 2008 | 12:13 AM
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of course ill flush my system, but not flush it to trust my heater core the rest of the winter....a once clogged heater core is never good to trust...and plus its not that hard to change it anyways...

on another note!! when you change your heater core its not a bad idea to change your hoses...
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Old Jul 19, 2021 | 06:03 PM
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Originally Posted by TDavanzo
A few weeks back when the weather turned cold I noticed that my heat wasn't blowing like it should so I figured I'd flush the heater core.

I never honestly knew it would make that big of a difference and it's so easy. It's amazing what that little amount of gunk can do to the cooling system.

If anybody is having this problem don't hesitate to try and flush your heater core -- its simple and makes a huge difference.

Figured I'd just post this for the guys who are scratching their heads about their heating problems. Try this first!!
Just did a heater core flush and got a little bit of gunk out, but just thought I'd make a note for anyone else who has this issue.

Initially I tried to flush and got instant pressure back, I figured it was just REALLY badly clogged. Turns out some halfwit had installed two heater taps in series on the return heater hose. One was mechanically operated but the cable wasn't even connected and doesn't move anyway, and the other one is vacuum operated. I got some new hose and cut out the mechanical one and put a new vacuum one in and it works like a charm now!
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