Flushing heater core over winter break
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From: Ft. Wayne, IN
Flushing heater core over winter break I've got a 2 week winter break coming up starting next week and I've decided to flush out my heater core as I'll be doing nothing with those weeks off. As of right now, heat takes about 4 minutes to get lukewarm and about 6 minutes to get warm. This is right after I start it in the morning at about 28°. It still defrosts my windshield and I don't have any leaks so I'm just going to try to flush it hoping it'll help it warm up faster and hotter. I'm going to take the core out of the car and run a hose through it and see what I can get out of it. I'm doing this mainly for experience and something to just take up time, but hopefully I'll get something good out of it too. Car is a 95 with 165k on it.
Was wondering if fluid will be in the heater core when I take it out, I'm hoping I don't have to drain the coolant first but I will drain if I have to.
And what coolant would be good to top it off with?
Was wondering if fluid will be in the heater core when I take it out, I'm hoping I don't have to drain the coolant first but I will drain if I have to.
And what coolant would be good to top it off with?
I've got a 2 week winter break coming up starting next week and I've decided to flush out my heater core as I'll be doing nothing with those weeks off. As of right now, heat takes about 4 minutes to get lukewarm and about 6 minutes to get warm. This is right after I start it in the morning at about 28°. It still defrosts my windshield and I don't have any leaks so I'm just going to try to flush it hoping it'll help it warm up faster and hotter. I'm going to take the core out of the car and run a hose through it and see what I can get out of it. I'm doing this mainly for experience and something to just take up time, but hopefully I'll get something good out of it too. Car is a 95 with 165k on it.
Was wondering if fluid will be in the heater core when I take it out, I'm hoping I don't have to drain the coolant first but I will drain if I have to.
And what coolant would be good to top it off with?
Was wondering if fluid will be in the heater core when I take it out, I'm hoping I don't have to drain the coolant first but I will drain if I have to.
And what coolant would be good to top it off with?
If you are not overheating the engine....the heater core is probably as clean as it can be.
But....if you want to flush the heater core....just do a complete coolant system flush using a degreaser/water mix.
Easy way to clean the heater core:
Just pop BOTH heater core hoses off.....stick a hose in one of them and blast water through the heater core. Takes 5 minutes and the core is clean. You can also pour degreaser into one of the hoses to fill the heater core....let it sit for awhile....then blast it out with the hose.
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From: Schiller Park, ILL Member: #317
Wow, I would never go to the hassle of heater core removal on a 4th gen just to clean it. That's a lot of work for no reason (if it's not leaking). If you want to flush it, do as LS6427 suggested above.
PS. Sounds like it's giving heat just about as quick as I would expect in those outside temps on a cold start.
PS. Sounds like it's giving heat just about as quick as I would expect in those outside temps on a cold start.
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Vinegar will do a great job cleaning a heater core. Just drain the rad and add a gal of vinegar, run for about 15 then add baking soda. Run for another 15 to neutralize the acids then dump and flush everything. Replace with new coolant, system should look like new again.
Vinegar is very mild acid and works great to clean the cooling system without harming anything. Baking soda is great for cleaning and neutralizing the system. I've done a bunch of very mucked up systems this way and it always works nice. If the heater core is really blocked you may need to let it sit for a few hrs after you put the vinegar in.
The heater core is the bypass in these systems so its the place all crap builds up.
Vinegar is very mild acid and works great to clean the cooling system without harming anything. Baking soda is great for cleaning and neutralizing the system. I've done a bunch of very mucked up systems this way and it always works nice. If the heater core is really blocked you may need to let it sit for a few hrs after you put the vinegar in.
The heater core is the bypass in these systems so its the place all crap builds up.
Last edited by RockinWs6; Dec 19, 2014 at 04:14 PM.
honestly man, that time sounds about right, thats what it takes mine, at these temps the simple act of driving makes the engine take that long just to get up to temp, you don't really start getting heat till the thermostat opens up (atleast thats what I've noticed) you could go to a lower temp thermostat to get heat coming a little bit sooner but it will take a LOT longer to get the level of heat you want, trust me I know, switching to a 180* from a 195* was proven to be a bad idea when winter came around.
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From: Schiller Park, ILL Member: #317
Not sure what car you did this on, and I know the OP mentioned having a '95, but just for future reference all the LS1 F-bodies came with 86°C (187°F) t-stats stock. So the move to a 180° would only be a 7° difference.
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Before doing the flush you might want to be sure that you actually have a problem and that it's the heater core. They rarely get plugged and the problem is usually just the fact that the engine just doesn't come up to temperature fast enough, If that's the case a even a new heater core won't fix it. If your thermostat is stuck open it can take longer to warm up.
Keep in mind that even putting a higher temp thermostat will not make it warm up faster, It doesn't matter if you have a 180* or a 195* both will be closed until the water temperature reaches the preset temp and that usually doesn't happen until you drive the car for a little bit.
If the temp gauge is showing that it's up to operating temperature and you still don't have heat then I would say you could have a problem with the heater core but if you let it run for 5-10 minutes and the temperature gauge is still reading low then it's probably not the heater core.
I would start by pulling the thermostat and test it, If it's stuck open you see that as soon as you remove it. If it's not open when you pull it you can test it by putting it and a thermometer in a pan of cold water on the stove and crank up the heat and watch for it to open. If it opens before the thermostats rating then it's bad. If it open at or near it's rating then you can eliminate that as a the problem.
Keep in mind that even putting a higher temp thermostat will not make it warm up faster, It doesn't matter if you have a 180* or a 195* both will be closed until the water temperature reaches the preset temp and that usually doesn't happen until you drive the car for a little bit.
If the temp gauge is showing that it's up to operating temperature and you still don't have heat then I would say you could have a problem with the heater core but if you let it run for 5-10 minutes and the temperature gauge is still reading low then it's probably not the heater core.
I would start by pulling the thermostat and test it, If it's stuck open you see that as soon as you remove it. If it's not open when you pull it you can test it by putting it and a thermometer in a pan of cold water on the stove and crank up the heat and watch for it to open. If it opens before the thermostats rating then it's bad. If it open at or near it's rating then you can eliminate that as a the problem.
Last edited by LLLosingit; Dec 19, 2014 at 10:59 PM.
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Its actually just the opposite, the heater core is the 1st thing that gets plugged in a system because coolant is ALWAYS flowing through it. Its also the coldest point in the cooling system so crap wants to settle there.
I have never even heard of a cooling system actually getting so dirty or contaminated with power steering fluid.....that there was actually a clog that stopped the flow or even slowed it down enough to make a difference.
I mean think about how thick or how gummy the coolant would have to get. Im sure its happened where the flow was slowed down.....but to stop the flow.....Id like to see what caused that to happen.
The worst Ive seen was a radiator where if you put your fingers down in there it had maybe 2mm's thick of black/brown sludge......because PS fluid was leaking into it for a very long time. But there was no overheating issue. We just opened it up to check after my friend said he keeps having to top off his PS fluid but he sees no leaks on the ground or under the hood. He said he probably poured 2-3 bottles in to top it off over about one year. He never checked his coolant. The overflow tank was also FULL of black crap. But is coolant flow was always sufficient to do its job.
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I mean think about how thick or how gummy the coolant would have to get. Im sure its happened where the flow was slowed down.....but to stop the flow.....Id like to see what caused that to happen.
The worst Ive seen was a radiator where if you put your fingers down in there it had maybe 2mm's thick of black/brown sludge......because PS fluid was leaking into it for a very long time. But there was no overheating issue. We just opened it up to check after my friend said he keeps having to top off his PS fluid but he sees no leaks on the ground or under the hood. He said he probably poured 2-3 bottles in to top it off over about one year. He never checked his coolant. The overflow tank was also FULL of black crap. But is coolant flow was always sufficient to do its job.
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From: Bucks County, Pa.
Yes, like most stated above, I could only WISH that my heater gave heat that quickly in the cold winter ambient temps!! 
True, I have a 180* stat to slow things a little, and no AC condenser blocking the LT1 replacement radiator (IF that has any bearing at all?), but I am lucky if I see even luke warm air after 15 minutes of highway driving!
Still, that quick core flush that LS6427 suggested above sounds like a good idea if you are not doing a complete system flush.
True, I have a 180* stat to slow things a little, and no AC condenser blocking the LT1 replacement radiator (IF that has any bearing at all?), but I am lucky if I see even luke warm air after 15 minutes of highway driving!
Still, that quick core flush that LS6427 suggested above sounds like a good idea if you are not doing a complete system flush.
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From: Ft. Wayne, IN
Hmm there's a lot of mixed views on this it seems like, but almost all of you say that warm air starts about after 5-8 minutes after you run the engine, or at least until the thermostat opens and coolant starts flowing through. The main thing that sparked my thoughts on this is that I was in a truck that started from a cold start and warm air started pouring through the vents roughly 30 seconds after starting the vehicle...?
I wouldn't pull out the entire heater core out either, it's just because I want to hah. I'm a very hands on, visual learner + I have ample time to do it and I want to say I did it
I'll pull it Monday, I'll keep you guys updated on the before and after
I wouldn't pull out the entire heater core out either, it's just because I want to hah. I'm a very hands on, visual learner + I have ample time to do it and I want to say I did it
I'll pull it Monday, I'll keep you guys updated on the before and after
I'm not sure where you heard that but considering the heater core is always seeing high flow they rarely clog and almost never get deposits. I've replaced quite a few in my lifetime and most are due to leakage due to corrosion and the few that were clogged were because someone thought it was a good idea to use stop leak.
Most heater cores are not on the thermostat side of the system so as soon as you start it the water if flowing thru the core, This is to help get heat to the cabin faster.
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From: Ft. Wayne, IN
This was one of my thoughts, but wasn't 100% sure on it. That clears up some confusion for me, thanks.
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The heater core circuit IS THE BYPASS for most all engines. It keeps the coolant circulating in the engine without having the thermostat open. It is the point in the system where crap collects 1st because its the coolest point besides the overflow bottle. The overflow will collect crap too because it cool. How do I know all this you ask? I've been doing this for about 45 years.....................
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I'm not sure where you heard that but considering the heater core is always seeing high flow they rarely clog and almost never get deposits. I've replaced quite a few in my lifetime and most are due to leakage due to corrosion and the few that were clogged were because someone thought it was a good idea to use stop leak.
Last edited by RockinWs6; Dec 21, 2014 at 07:52 AM.
The heater core circuit IS THE BYPASS for most all engines. It keeps the coolant circulating in the engine without having the thermostat open. It is the point in the system where crap collects 1st because its the coolest point besides the overflow bottle. The overflow will collect crap too because it cool. How do I know all this you ask? I've been doing this for about 45 years.....................
I guess you didn't know that the major cause of corrosion in a cooling system is Electrolysis due to worn out acidic coolant. Some manufacturers even added ground straps to core to help alleviate the problem.
Thats why I also always carry one of these in my car.....just cut the ends even with a razor knife and put it in with the spare tire. If you ever spring a heater core leak, pop it on and keep going.
http://www.summitracing.com/parts/da...XYBhoC1u7w_wcB
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