Heater Core Flush?

Does anyone know what could be used to disolve some of the Dexcool sludge out of the core on my 96? I flushed it back in November with just water and it worked great for about 2-weeks, then slowly lost temperature until no heat at all?

Buy a Prestone Flush N Fill kit, it is a "T" that you install in your heater hose so that you can connect your water hose straight up to it and back flush it. Then use the Prestone Radiator Cleaner. Not the "flush" get the "cleaner". The flush is used for twenty minutes while idling. The Cleaner is used for 3-6 hours while driving, you just drain your system add the cleaner, fill up with water, then drive a few days with your heater on (you don't have to have the fan on, just the temperature control all the way up), then when you drain it all the sludge comes out leaving your radiator and heater core spotless. Then connect your hose to the "T" again and back flush one more time, this will get everything out.
After that Fill with a 50/50 mix of DEXCOOL ( or the green if you prefer, at this point your system is clean enough to convert) and distilled water. NEVER MIX THE TWO! You will have to keep topping it off over the next few days as the air is worked out of the system.

AND THE ABSOLUTE MOST IMPORTANT THING IS TO REPLACE YOUR RADIATOR CAP, WITH ONE NOT MADE BY AC DELCO. THE AC DELCO ONES THAT CAME ON THESE VEHICLES ARE DEFECTIVE. THAT IS WHAT CAUSED YOUR PROBLEMS IN THE FIRST PLACE. THE BEST ONE TO BUY IS THE "STANT" BRAND YOU CAN PICK THEM UP AT ADVANCE AUTO FOR ABOUT 5 OR 6 BUCKS.

The Prestone Flush N Fill ($4) and the Prestone Radiator Cleaner ($6) can be bought at any parts store and walmart.

Thanks,

I did the flush kit already, apparrently the cleaner works better. I already switched to the new Prestone green, I will NEVER be using Dexsludge again! Unfortunately it is about-6 deg. here, so I guess I will be without heat until it warms up this spring.

If you follow the procedure above there is a very good chance that you will have heat again. Have you replaced you radiator cap? even though you have gotten rid of the DEATH-COOL your cooling system will still work better with the proper cap.

Thanks,

I did the flush kit already, apparrently the cleaner works better. I already switched to the new Prestone green, I will NEVER be using Dexsludge again! Unfortunately it is about-6 deg. here, so I guess I will be without heat until it warms up this spring.

Chances are you didn't get all the dexcool out and the green and orange mixed to create gray sludge.

There is nothing wrong with Dexcool. The only problem is the rad cap and people not doing the proper maintanence like waiting almostt 10 years to replace the coolant when it was supposed to be done in 5.

I ran it for 20 minutes with the garden hose hooked up to the tee, so I know there was no dex left in it. There are no signs of grey sludge in the radiator, and the cross tubes are still clean and flowing. I did put a Stant cap on too before all of this just to be safe. I am noticing brown chunkies in the heater hoses again and the outlet hose is not as hot as the inlet so I guess some more worked loose from the motor.

The water can only clean where it can circulate. If there are sections clogged up. The water won't help that much, you need to use a chemical to disolve the sludge before those area will be cleaned.

Very true, water dissolves nothing.

I just did my own heatercore flush a few days ago and now I have burning hot heat in subzero temperatures-> success! Cost: $1.50 (in quarters)

I went to a "diy" car wash and disconncted the 2 heatercore hoses and blasted it with the high pressure hose. There was definetely residue and "clay" in there, but it was whitish mud (maybe just mixed with water). It worked great, no mess, and ony took 5 minutes. The high pressure of the hose was more than that of a garden hose, and I think that did the trick.

*Note you have to let your vehicle cool down before disconnecting heatercore hoses. I didn't do this because my hoses weren't hot (because of blockage), but the block was still hot. Coolant was everywhere. Thank goodness it wasn't on my driveway.

I just did my own heatercore flush a few days ago and now I have burning hot heat in subzero temperatures-> success! Cost: $1.50 (in quarters)

I went to a "diy" car wash and disconncted the 2 heatercore hoses and blasted it with the high pressure hose. There was definetely residue and "clay" in there, but it was whitish mud (maybe just mixed with water). It worked great, no mess, and ony took 5 minutes. The high pressure of the hose was more than that of a garden hose, and I think that did the trick.

*Note you have to let your vehicle cool down before disconnecting heatercore hoses. I didn't do this because my hoses weren't hot (because of blockage), but the block was still hot. Coolant was everywhere. Thank goodness it wasn't on my driveway.

Although it did help, you need to have your cooling system flushed and refilled with fresh coolant or the problem will quickly come back.

Don't start being cheap, get the job done properly.

Although it did help, you need to have your cooling system flushed and refilled with fresh coolant or the problem will quickly come back.

Don't start being cheap, get the job done properly.


somewhere along the line i was told that if you use dexcool then switch to standard green it has a reaction with the residue possibly causing permanent damage to some components,not sure if its true or not.just thought i would mention it


fllatire

somewhere along the line i was told that if you use dexcool then switch to standard green it has a reaction with the residue possibly causing permanent damage to some components,not sure if its true or not.just thought i would mention it


fllatire

What you heard is right.

Dexcool is used in our engines because it is non corrosive.

Although it did help, you need to have your cooling system flushed and refilled with fresh coolant or the problem will quickly come back.

Don't start being cheap, get the job done properly.

It wasn't my goal to be cheap, but to get the job done as well and as fast as possible. It was way too cold to spend an hour (or an afternoon) trying to fix this problem as I have no garage. Aside from that the nearest autoparts store that has those flush products is a half hour away, and I don't have time for that either. For now the heatercore heats up fast and keeps me warm better than I ever imagined it could.

BlazerLT has this under control fairly well, but let me add a note or two to this concern.
The problem is the heater core clogging up...the cause is the buildup of sludge in the engine cooling passages that are getting stuck in the heater core.
if you flush just the core, you are masking the problem not solving it.

Go ahead and spend the time to completely flush the cooling system..its better to do something right once than wrong a bunch of times.

Just a reminder when I say "Green" I am referring to the new Prestone "Geen" that is compatible with Dex-Cool. If you don't completely eliminate the Dex and add the "old" green Prestone, you will get a sludge problem after time.

Just my $.02

From a chemistry standpoint Dexcool is propylene glycol and is mixable with water at all concentrations. Old green antifreeze is ethylene glycol and is also mixable with water at all concentrations.

Dexcool (propylene glycol) apparently polymerizes under certain conditions *my guess is a small amount of engine oil mixed with iron oxides* (which is the sludge observed in the heater core).

They switched to propylene glycol (Dexcool) from ethylene glycol (old green), primarily for environmental concerns (cats like the taste and it crystalized their kidneys... it also harms dogs and humans in high enough concentrations).

Ethylene glycol has better properties (regarding raising boiling point and lowering the freezing point of the coolant) than propylene glycol at the same concentrations.

So to make Dexcool sound better, they increased the concentration of the rust inhibitors and pH buffer and gave it a longer listed operating value (ie. 150, 000 miles vs. 30,000 miles for old green).

This is all my opinion as a chemist and I am willing to debate my conclusions.

Just a reminder when I say "Green" I am referring to the new Prestone "Geen" that is compatible with Dex-Cool. If you don't completely eliminate the Dex and add the "old" green Prestone, you will get a sludge problem after time.

Just my $.02

From my knowledge, the compatible stuff is yellow.

Anything green is non compatible and has a silca based formulation.

Yeah, the new prestone that is compatible with everything is yellow.

You guys are right, it is yellow... I know I read Dex compatible and the stuff was $9.50 a gal!! I guess the $3.99 days are long gone..

Yeah I bought a gallon of the yellow for 8.99 when I flushed out my heatercore. I didn't need it though, because I had more than enough in my reservoir. Now I can't find the reciept.

Yea, stick to the proper coolant for your truack and don't experiment with the new stuff.

96 blazer...same deal...heater blows cold and engine runs hot, now i seem to have a pinhole leak just under the a.c. motor in the engine compart.(drivers side). sometimes i hear a gurgling under the dash and the temp goes down for a while,but pegs quickly after. flushing my heater core will fix it long enough to get it to the shop(in a couple days)
right?

96 blazer...same deal...heater blows cold and engine runs hot, now i seem to have a pinhole leak just under the a.c. motor in the engine compart.(drivers side). sometimes i hear a gurgling under the dash and the temp goes down for a while,but pegs quickly after. flushing my heater core will fix it long enough to get it to the shop(in a couple days)
right?

No, you need to do a complete flush. I sounds like you neglected your cooling system and your dexcool has turned to sludge. Judging by the problems you described the problem is larger than just your heater core your entire system is affected. I usually recommend doing the flush yourself, but in your case I would recommend a shop if your intake gasket is leaking, ( the leak near tha A/C) connecting a water hose to backflush could cause lots of damage. (you system leaks with 16 psi, usually a water hose has around 40 pounds of pressure just think of the damage....water in the cylinders, water in the oil. You will also need to change out your Radiator Cap with one not made by AC Delco, perferably a Stant (sold at Advance Auto for $5-$6).

You need to investigate to see where the leak is first, if it's not the intake gasket (maybe the water pump) you can safely fix this yourself without a shop.

FYI the gurgling in the dash is air in your heater core...a sign of a bad cap.

Yes, take it into the shop and have them perform a heater core and engine cooling system flush.

Also, are you saying the heater core is leaking in the passenger compartment?

Took it to the shop to get a complete system flush, said they couldnt do it because I had a leak. Needless to say I was quite "PO'd", because I just spent $1200 getting it registered...,new cat, tune up...etc, anyway I get it home tonite thinking I'll take it to the car wash and do it myself and I fill the radiator with water and notice now that it leaks ALOT underneath by the tranny but I cant find the actual leak. Me thinks I may have blown it!?

.... by the way, I've always loved the blazer post 93 body style and I just got this about two months ago....I'm getting slightly discouraged, but remain optomistic that my initial cost of purchase, $0, and the $1200 I spent to make it legal, I figure I'll go another $1500 or $2000, after that its not such a good deal anymore

excellent forum you guys have here. im having the same problem as most above on my 99 ZR2. Think i may bring it to jiffylube for a full system reverse flush.

Heater is blowing cold air, and gets luke warm at high idle. Im thinking it just needs a good flush. 56k miles. Any comments on bringing it to jiffylube? I'd do it myself, but i havent picked up a Haynes yet for the truck and i dont really have any place to dispose of the used antifreeze. Thanks for any help in advance.

The procedure is easy enough that you don't need a haynes book I can give you step by step directions and tell you what to get, it is cheaper to do it yourself and you can do a better job, but it is messy.

Although doing it yourself is ideal, changing coolant and doing the flush on your own in the winter is just messy as hell.

Seeing you only do it every 3-5 years, I recommend having a shop do it since they will collect the mess, and they have all the proper fitting and proper cleaners.

took it to jiffylube.... they did the full flush for 54 bucks... heat was still blowing cold air... made "buddy buddy" with the mechanic... showed him how to flush out the heater core.... we pulled both hoses off the block.... did reverse flush and forward flush a few mins each....heat is hot as ever.. .all fixed.... gave him a nice tip....

Im grateful to this forum for its insight.... thanks everyone...

remember, new rad cap

10-4 on the new cap. I know this is not the proper way, but I did the carwash trick on the core to back flush and it worked. I wish I had a heated garage so I can run cleaner through it with straight water, I'm to nervous with these cold temps to try and run it for 3-6 hrs. with h2o.

10-4 on the new cap. I know this is not the proper way, but I did the carwash trick on the core to back flush and it worked. I wish I had a heated garage so I can run cleaner through it with straight water, I'm to nervous with these cold temps to try and run it for 3-6 hrs. with h2o.

Take it to a shop and have it done properly.

I went to the parts store (Autozone) to get a new rad cap and they didn't have a 15 psi cap. The guy told me that anything between 13 and 17 psi would be fine. Is that true? I figure that if the system is made to be 15, it should stay 15, or is there a safety margin? Any help will be appreciated.

You can get a 16psi Stant from Advance Auto. The Stant brand are high quality and will last a long time.

My 2000 Jimmy had the same issue with little to no heat, gurgling sound on passenger side of truck. A quick inspection of the fluid level showed a little low but the coolant was still clear and orange. I did a self flush at home by removing both heater hoses completely from the heater core fittings and connecting a garden hose (with the end cut off) with a hose clamp directly to the smaller heater core hose fitting after running the Prestone "Flush" (not Cleaner) through it. I also flushed the engine block using the heater hose that goes into the top of the block. Everything seems to be working fine, plenty of heat and no more gurgling. But nothing beats a properly performed reverse flush. If your system was neglected it is the only sure way to get all of the crud out of you system. I also recommend that you never put tap water into your radiator. ALWAYS, ALWAYS, ALWAYs use DISTILLED Water. NOT bottled drinking water, go to the grocery store and buy DISTILLED WATER. It costs about $.50 a gal and is well worth the trouble.

don't get one that is less than 15psi.

16psi is fine.

Hey guys, I drive a 1997 grand prix GT ( I know it is different) but i also experience the same problems above. Mechanics performed a flush but that did not solve the problem and perhaps made it worse. Should i perform the flush myself? Any suggestions?

Hey guys, I drive a 1997 grand prix GT ( I know it is different) but i also experience the same problems above. Mechanics performed a flush but that did not solve the problem and perhaps made it worse. Should i perform the flush myself? Any suggestions?

They probably did a half ass job. If the system is clogged it needs to be backflushed well and cleaned with a chemical flush. You can do a lot better job than most shops will do, but it is a little messy.

Replace the cap as well.

All GM's with the stick cap are being affected by the poor cap.

Hey guys, I drive a 1997 grand prix GT ( I know it is different) but i also experience the same problems above. Mechanics performed a flush but that did not solve the problem and perhaps made it worse. Should i perform the flush myself? Any suggestions?

They might have done the flush incorrectly, but chances are you have airlock. I agree that you shouldn't use "ghetto flushes" to make up for neglecting your cooling system, but if you have maintained your fluids well or even payed a shop to flush and fill, more flushes might not get the air out of there.

If you want to do it yourself, follow one of these methods;

For system with Sludge:

Buy the following:
2 gallons of distilled water $1
2 gallons of Dexcool $20
Prestone Flush 'N Fill kit $4
Prestone Radiator "Flush" $4

Turn your heater on and leave it on for the entire process

Drain the anitfreeze from the system.

Install the "T" from the Flush 'N Fill kit and follow the directions that came with it.

Disconnect the water hose, close all the drains, add the Prestone Flush, fill with water, get engine up to operating temperature and run for 20 minutes, allow to cool then, drain the system.

Connect your water hose to the Flush 'N Fill "T" and flush one more time. Drain.

Fill the system with a 50/50 mix of DexCool and distilled water. Continue to fill the system over the next few days as the air is worked out of the system.








For clogged, neglicted, or extremely dirty systems:

Buy the following:

2 gallons of distilled water $1
2 gallons of Dexcool $20
Prestone Flush 'N Fill kit $4
Prestone Radiator "cleaner" not "flush" $6

Turn your heater on and leave it on for the entire process

Drain the anitfreeze from the system.

Install the "T" from the Flush 'N Fill kit and follow the directions that came with it.

Disconnect the water hose, close all the drains, add the Prestone Cleaner, fill with water, run the engine 3-6 hours (you can leave it in for a few days if neccessary), drain the system.

Connect your water hose to the Flush 'N Fill "T" and flush one more time. Drain.

Fill the system with a 50/50 mix of DexCool and distilled water. Continue to fill the system over the next few days as the air is worked out of the system.

BlazerLT,

How about putting my last post on a sticky for radiator maintenance, you should probably add to change the rad cap though.

Will consider it when the condensing commenses.

This airlock you speak of, is there a good chance i can solve it by the methods you listed? Mechanics tell me that the heater core typically needs to be replaced? Is this usually the case or does a thourough flushing/cleansing take care of it most of the time?

This airlock you speak of, is there a good chance i can solve it by the methods you listed? Mechanics tell me that the heater core typically needs to be replaced? Is this usually the case or does a thourough flushing/cleansing take care of it most of the time?

Needs to be replaced when?

This airlock you speak of, is there a good chance i can solve it by the methods you listed? Mechanics tell me that the heater core typically needs to be replaced? Is this usually the case or does a thourough flushing/cleansing take care of it most of the time?

Sounds like they are trying to screw you, it should only be replaced if leaking. I haven't seen one yet that couldn't be unclogged. They will probably back flush and tell you they replaced it.

They might have done the flush incorrectly, but chances are you have airlock. I agree that you shouldn't use "ghetto flushes" to make up for neglecting your cooling system, but if you have maintained your fluids well or even payed a shop to flush and fill, more flushes might not get the air out of there.

Any air in the system will be removed by a properly working rad cap:

As the coolant circulates the air moves to the radiator (the highest point). As the temperature increases the coolant expands, this expansion causes pressure when the pressure reaches 16psi the air pushes past the cap and goes into the overflow which is vented allowing the air to escape. When the system cools back down it draws coolant back in from the overflow. After repeating this process several times all the air will be evacuated from the system.

If the cap is defective instead of drawing coolant in from the overflow it will leak around the cap pulling air back in to the system. That is why a properly working cap is crucial for a healthy system.

Phoenix69, First, I think you need to give us a few more symptoms of what exactly your problems are.

Second, If you are living in an area known for its hard water (like Phoenix), Radiator corrosion and plugged radiator/heater cores are much higher. If you perform a good thorough clean/flush as described by Blazee and install a new CLOSED LOOP Rad cap you should see improvement. Don't buy the AC Delco Cap! A new cap will force the air out automatically. You can easily verify this in the morning when the engine is cold. Open the rad cap and the observe the coolant level. It should be full to the very top of the radiator.

I would not just run out and drop $200-$300 for a new heater core. This is just a hungry mechanic trying to make a fast buck by screwing you.

Try disconnecting both heater hoses and attaching a garden hose directly to one of the heater core fittings, you might need a hose clamp. Turn the water on full force and see how much water is flowing through your heater core. This will blow any loose crud out of the core and might solve your problem. If you observe limited flow, or if you're having still having problems after the flush, Then it may be time for a new core.

I have read that if you turn it on full force you risk a chance of blowing a line, and also that if you run your engine while running cold water through it you run the risk of warping internal aluminum components from the great difference in temperatures.
Before i bought my car i saw that the coolant was in poor condition and thought that a good flush would fix it. When i did the test drives i didnt notice the sloshing noise. After i brought it home a few days later i noticed the noise. When my dad brought the car back for the flush that the manager had agreed to my car thermostat/thermometer blew out. I'm not sure if that has anything to do with the flushing or if it was just already dead. But anyways the flushing seemed to possibly have made it worse. I talked to another mechanic about the problem and he said that he's seen it several times with all makes of cars and that he flushed a mans system 7 times and it did not solve the problem, and that the system had to be replaced. He said that this may be the case with me, he told me this not looking for work (didn't say come back here or anything, seemed honest).

****The symtoms my car has are as follows:*******

1.) When the heat it turned fully up I get luke warm air from my blower even when the engine is fully warmed up (told that a clean system should almost burn your hand).

2.) Whenever I accelerate or take a turn/accerlate I can hear a sloshing noise, as if alot of water is going through tubes, sounds like a good gallon+ worth of water in front of the dash, perhaps moreso on the passengerside of my car.

I originally thought that the water noise i was hearing was a drain that had become blocked up or possibly a water filled cowl and started to retain rain water. Another thing that made me think this possible was a hole in the weatherstripping around my windshield at the bottom/passenger side. It seemed that after a rain storm the sloshing became louder (perhaps imagination). Mechanics said that they checked and did not find any blockages. I too checked the HAVOC box and other drains and have not found a blockage. All mechanics and other people on forums have directed me towards the conclusion that I have a clogged up heater core. It seems as if my 1997 Grand Prix has never been flushed. The car has 50,000 miles on it if that has any importance.

O.K. let me clarify. The actual flushing is done with the engine turned OFF. I kinda doubt the part about cold water warping engine components. How cold do you think the water is when you start the car in the morning when it is freezing outside? The worst that would happen is that the engine would probably run rich. However, to the point, make sure the engine is not running when you perform the flush.

If you diconnect BOTH heater hoses and connect a garden hose, you should get some flow through the core, and very little pressure build up. If you don't get any flow through the heater core, it won't matter as the core is plugged solid and probably shot.

Have you replaced the Radiator cap yet?

Your core is probably not even clogged if you have been through all those flushes. Airlock in the heatercore is very common. While you car is cold do the heatercore flush that has been outlined.

Sounds like the rad cap is leaking in air.

Replace with anything other than a AC Delco, Stant is the right brand at Autozone.

Also, did they reverse flush the heater core?

I'm not sure if they did reverse flush on my heater core. Can you help me pick of the exact rad cap that i need?

Go to autozone and use their application guide to get the right stat for you.

The Autozone in my area doesn't sell Stant. Around here you have to go to Advance Auto. Autozone doesn't sell them online either.

Would Pepboys have it?

Probably. Any other brand name except AC Delco will do just fine. I'm running whatever the generic brand name is that Autozone sells. The AC Delco's leak air, that's why you don't want them.

i had the problem of cold heat, i flushed my radiator today and its awesome, try that see how it works

97blazr2, did you get the radiator or the heater core flushed?