Got air in your heater core? Need help getting rid of it?

I recently have had the gurgling water noise under the dash and I again replaced my rad cap that for some reason failed again but I still was not getting the air out of the core.

You want to know how to get rid of it, here is the trick.

Have the front of the truck and radiator higher than the heater by using ramps or parking it on a steep hill. This will have the air being forced to the top spot it in the cooling system which is the rad now. Make sure that you have the rad cap side slightly higher as the rest of the rad as well. This will have you getting rid more of the air.

1.) Turn the heat to full and the directional controls to panel or floor. Turn the fan to medium speed.

2.) With a cold engine only, remove the rad cap, start the engine and hold the engine revs at 1500-2000rpms until the engine warms up and the thermostat opens. You will see the coolant quickly drop when the thermostat opens. This is the time to start adding your 50/50 mix of dexcool and distilled water. Add until it is right up to the top and you will see the air bubbles coming up as the coolant displaces the air in the heater core. Continue this for about 10 minutes or until no more air bubbles is coming out. Don't worry if small amounts of coolant is coming out of the rad fill neck, you want that.

When no more air bubbles are being seen or the coolant level is not dropping anymore, install a new stant rad cap and drop the engine back down to idle.

Now, be patient, there might be a little more air in the system for another day or two by right after doing this, take the truck for a god 50 mile run to make sure the coolant is getting everywhere it should be.

since I did this, nothing but slosh-free driving.

Enjoy guys! ;)

what will air in the heater core do?

Air in the heater core will allow partial evaporation of water out of the coolant. Over time, this very corrosive, concentrated coolant will eat its way through the aluminum where there is no solid stream of coolant flowing and perforate the heater core. Keeping your system topped up and air-free keeps you from having blown out heater cores or eaten out and leaky top passages in your radiator too. Keep the system totally topped up and air free as much as possible.

Great topic.
I had no idea this would happen.

Mine just started the gurgling recently.

Guess its off to the local auto parts store for a cap and some coolant.

Lt, do you think one drive on ramp on the passenger side would be high enough?

Air in the heater core will allow partial evaporation of water out of the coolant. Over time, this very corrosive, concentrated coolant will eat its way through the aluminum where there is no solid stream of coolant flowing and perforate the heater core. Keeping your system topped up and air-free keeps you from having blown out heater cores or eaten out and leaky top passages in your radiator too. Keep the system totally topped up and air free as much as possible.

Actually, it is not the concentrated coolant that eats heater cores, it is the acid formed when Dexcool is exposed to oxygen and heat that does the eating.

Most heater core failures are a result of electrolysis. These leak due to pin holes caused by electricity flowing through the cooling system to ground. There are two main causes of electrolysis..... faulty engine grounds, and non-maintained coolant getting acidic causing it to become ionized and produce voltage. (like a battery.)

You can test your system with a voltmeter, place the positive lead in the coolant and the negative lead on the negative post of the battery. Any reading above .3v can cause heater core failure.

Essentially wolfox and BlazerLT are both correct.... Dexcool uses OAT (Organic Acid Technology). Higher concentrations of dexcool means higher concentrations of acid. The higher concentrations of acid cause the coolant to become ionized and "eat" or "burn" through the core.

All the above would also apply to other parts of the system, such as the radiator.

So what if I dont use the infamous Dexcool and I just use regular antifreeze?

Is there still the same potential for disaster?

So what if I dont use the infamous Dexcool and I just use regular antifreeze?

Is there still the same potential for disaster?

Yes, if you mix them, you will make a hideous brown sludge that will essentially clog your whole cooling system.

great topic lt, very simple and kinda 'obveous' but then again no one thinks of it... and seince joules brought this up, if your system is designed for dex cool use it, it has a different base designed not to eat at that rubberband/plastic intake gasket you have, coolent is not just coolent, keep it green if its a green system, keep it dex if its a dex system

Would there be a real big problem with replacing the dexcool with the green stuff, i replaced the dexcool with the green stuff in my current 2000 blazer because the dexcool destroyed my well maintained 97 blazer in April, so when I got my 2000 blazer in april i immeditly flushed the system and replaced the dexcool with the green stuff and have not seen or heard any noises or tell tale signs of the crappy dexcool anti freeze, after doing a intake gasket job on my 97, I saw that all of the coolant ports going from the head to the intake were almost completely clogged, with the brown sludge, and I kept my 97 very well maintained and the dexcool still destoyed it, so i went with the green stuff, and havent seen or heard a problem since, but my question would be, what harmful effects does the green stuff have, let me rephrase, what "legitamate" effects will it have, i want to know proven problem, not what some will "think" might happen, thanks again!

Ummm, how do I keep the engine at 1500-2000rpms and watch the coolant level at the same time?

you manually open the throttle under the hood. On my 00 jimmy there are 2 cables running up by the intake, the one on the right is the throttle

you manually open the throttle under the hood. On my 00 jimmy there are 2 cables running up by the intake, the one on the right is the throttle

No, you can't do that seeing you will need both hands and you will need to hold it open for 10-15 minutes sometimes.

I suggest a piece of wood under the gas pedal to keep it open and constant.

Would there be a real big problem with replacing the dexcool with the green stuff, i replaced the dexcool with the green stuff in my current 2000 blazer because the dexcool destroyed my well maintained 97 blazer in April, so when I got my 2000 blazer in april i immeditly flushed the system and replaced the dexcool with the green stuff and have not seen or heard any noises or tell tale signs of the crappy dexcool anti freeze, after doing a intake gasket job on my 97, I saw that all of the coolant ports going from the head to the intake were almost completely clogged, with the brown sludge, and I kept my 97 very well maintained and the dexcool still destoyed it, so i went with the green stuff, and havent seen or heard a problem since, but my question would be, what harmful effects does the green stuff have, let me rephrase, what "legitamate" effects will it have, i want to know proven problem, not what some will "think" might happen, thanks again!
ok, as i said in post number 9 i beleve, the green stuff has a different base from the Dex cool, the green likes to eat away at that plastic rubber intake gasket, and you will eat through the seal with green... and to get brown sludge in a Dex system, your 97 was not taken well care of, Dex cool sludges up when it is mixed with oxygen and exposed to heat (will do it in just oxy. but the heat speeds the process up) keep a good rad. cap (factory ones are shitty) on the dex cool and keep it toped off and you will have no problems with it

ok, as i said in post number 9 i beleve, the green stuff has a different base from the Dex cool, the green likes to eat away at that plastic rubber intake gasket, and you will eat through the seal with green... and to get brown sludge in a Dex system, your 97 was not taken well care of, Dex cool sludges up when it is mixed with oxygen and exposed to heat (will do it in just oxy. but the heat speeds the process up) keep a good rad. cap (factory ones are shitty) on the dex cool and keep it toped off and you will have no problems with it

Perfectly said.

if dexcool is more acidic than the green stuff then why would the green stuff eat the gaskets faster?

who said dex was more acidic?

who said dex was more acidic?

Yea, I don't think anyone said that.

I will have to check, but it wil become corrosive or acidic when exposed to air and heat.

Either of the conditions is damaging.

I beleive Blazee said it

"Essentially wolfox and BlazerLT are both correct.... Dexcool uses OAT (Organic Acid Technology). Higher concentrations of dexcool means higher concentrations of acid. The higher concentrations of acid cause the coolant to become ionized and "eat" or "burn" through the core."

And BlazerLT, i have read many of your posts in many topics and it seems that you are very negative about everything that is said on this forum, im sure that im not the only one that has noticed that.

I beleive Blazee said it

"Essentially wolfox and BlazerLT are both correct.... Dexcool uses OAT (Organic Acid Technology). Higher concentrations of dexcool means higher concentrations of acid. The higher concentrations of acid cause the coolant to become ionized and "eat" or "burn" through the core."

And BlazerLT, i have read many of your posts in many topics and it seems that you are very negative about everything that is said on this forum, im sure that im not the only one that has noticed that.

What? Negative what?

Yea, I am negative about everything aren't I ya tool.

Who made this thread arse? ME! And that is a positive contribution to this forum about how to bleed air out of your cooling system, not a thread for you to discuss your hate for Dexcool.

Besides, I am no the one who questioned you saying it was acidic, dmbrisket 51 was.

So go back to your 2 green coolant threads if you want to be a baby.

OK BlazerLT you had this to say about the quote

Quote:
--------------------------------------------------------------------------------
Originally Posted by dmbrisket 51
who said dex was more acidic?
--------------------------------------------------------------------------------

"Yea, I don't think anyone said that."

So yes you did!

And another thing it doesnt look like you have much of a life outside of you "awesome" 95 blazer, because if you look down the list of threads, all I see is your name on every thread, so when your done living online on the blazer forums, why dont you get a real job and grow up not worry about what every little thing anyone posts or throws out there. Ok, so who is the tool now, LOSER!

I wish I had nothing to do all day but sit around and read the Blazer Forums and tell everyone what a bad job they are doing with their car and how they should be posting threads on this stupid forum.

And another thing it doesnt look like you have much of a life outside of you "awesome" 95 blazer, because if you look down the list of threads, all I see is your name on every thread, so when your done living online on the blazer forums, why dont you get a real job and grow up not worry about what every little thing anyone posts or throws out there. Ok, so who is the tool now, LOSER!

I wish I had nothing to do all day but sit around and read the Blazer Forums and tell everyone what a bad job they are doing with their car and how they should be posting threads on this stupid forum.

http://x10.putfile.com/10/27916575470.jpg (http://www.putfile.com)

It is called owning your own business and I am sorry I like helping nice Blazer owners, not childish posters like yourself.

BlazerLT, i sent you a private message, please read

BlazerLT, i sent you a private message, please read

Ok, we are kewl.

to everyone, xjcamaro89 and I have buried the hatchet and both have straightened this out.

I beleive Blazee said it

"Essentially wolfox and BlazerLT are both correct.... Dexcool uses OAT (Organic Acid Technology). Higher concentrations of dexcool means higher concentrations of acid. The higher concentrations of acid cause the coolant to become ionized and "eat" or "burn" through the core."

And BlazerLT, i have read many of your posts in many topics and it seems that you are very negative about everything that is said on this forum, im sure that im not the only one that has noticed that.
and they are correct if you think about what they said, the higher concentration of DEX COOL means higher acid levels.... meaning if your not at your 50/50 water to dex if you are 75/25, there is more acid there then if the mix is correct, the green stuff is accually more corrosive then dex, dex just has a problem with air, which unfortunetly, is all around us

thank you

and they are correct if you think about what they said, the higher concentration of DEX COOL means higher acid levels.... meaning if your not at your 50/50 water to dex if you are 75/25, there is more acid there then if the mix is correct, the green stuff is accually more corrosive then dex, dex just has a problem with air, which unfortunetly, is all around us
The green isn't more acidic or corrosive than Dexcool. The green contains silicates, borates, and phosphates which make it more alkaline not acidic. These corrosion inhibitors do, however, make the antifreeze very abrasive. The abrasive (not corrosive) properties of the green antifreeze is what causes wear to the system. Dexcool uses OAT and not the abrasive corrosion inhibitors, which would make it much better at protecting cooling system componets, IF it weren't for Dexcool's one weakness .... it is easily contaminated and once contaminated, it becomes destructive.

Under perfect conditions, Dexcool would be far superior to the old standard green antifreeze. However, your engine is not a lab, and conditions aren't always perfect. I use the green stuff, knowing that the abrasive additives that it contains are slowly wearing the cooling system componets, because in my opinion, it is safer. I consider it safer, because you don't have to worry about it sludging up and plugging your system. Another concern with dexcool is that it has less of an "alkaline reserve" due to it's acidic properties, because it has less of an alkaline reserve it can become acidic to the point that it becomes ionized, and electrolysis damages your system without you even knowing, until it's too late. It takes the silicates in the green antifreeze years to wear through the system, extreme cases of electrolysis can eat through system componets in a matter of days.

If the green stuff has all of these abrasives in them, then why dont cars that take the green stuff have the problems that you are talking about in the dexcool cars. This is what Im saying, in the cars that take the green stuff, the coolant is in contact with the same type of rubber and plastic conponents as the dexcool cars, now maybe not in the same location, but somewhere in the coolant system both types of cars coolant parts are exposed to the coolant one way or the other, so if I use the green in my dexcool car wont i run the risk of the problems everyone else faces with the green coolant cars? You get what im saying? Just to me in my mind all cars coolant systems are basically the same and your going to have the same problems with the green stuff in either type of car. i think thats what im trying to say.

A newer car with the green stuff will have the same problems with the green stuff that the older ones do. (which is not much) The wear caused by the abrasives is minimal when compared to the time it takes to cause problems.

Changing older cars over to Dexcool will not yield much of a benefit, because it doesn't protect the old lead soldered copper and brass componets as well as it does newer aluminum systems.

Blazee is dead on. A properly balanced and maintained Dexcool based system using the Havoline "Dexcool" product will not experience much trouble. The key is VIGILANCE. There are abrasive, suspended components in the "Green" anti-freeze mix that will wear on parts much, much faster than a maintained Dexcool system. When I got my truck's Radiator, pump, hoses and other miscellany taken care of (including a leaking lower intake seal) I had completely dumped, flushed, and re-flushed the green stuff out and put Dexcool back in. She's happier than ever with a Stant cap topping off the radiator neck.

Blazee is dead on. A properly balanced and maintained Dexcool based system using the Havoline "Dexcool" product will not experience much trouble. The key is VIGILANCE. There are abrasive, suspended components in the "Green" anti-freeze mix that will wear on parts much, much faster than a maintained Dexcool system. When I got my truck's Radiator, pump, hoses and other miscellany taken care of (including a leaking lower intake seal) I had completely dumped, flushed, and re-flushed the green stuff out and put Dexcool back in. She's happier than ever with a Stant cap topping off the radiator neck.

What about using the Prestone Dexcool? :(

The Prestone Dexcool is very similar to the Chevron/Texaco/Havoline. They have different corrsion inhibitors, but I haven't seen any research showing one to be better than the other.

God mercy jesus I hope not. I just completely redid my cooling system with it, a new thread is in the works talking about it.

I found some discussion about the different corrosion inhibitors at bitog, it seems that most of those guys agree that it shouldn't make a difference in performance, and that the difference was probably to get around Texaco's patents:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=37;t=000161;p=1#000 010

Texaco/Havoline are the folks that made the original factory fill fluid for "Dextron" when the trucks rolled off the lot. With the additive chemistries havin been changed and made a litle more tollerant in recent years, I doubt that Mixing Prestone's "Dexcool" compatible fluids with Havoline/Texaco's going to make one bit of difference. If you're that paranoid about it (like I am) drain the stuff out to be recylced in two, three year intervals and refill with fresh pre-mix or distalled water/straight Dexcool in your usual 50-50 mix ratios.

I am currently using a slightly higher concentration seeing it gets to -40f here in the winter.

I am currently using a slightly higher concentration seeing it gets to -40f here in the winter.

Yeah, a 50-50 mix of Dexcool protects down to about -36 degrees according to the charts I looked for on the web just a minute ago. It can go as low as -80 degrees or so at 60-40 ratios, but I would not go that "deep" with it. I do not know if Dexcool is the same as the old green glycol based stuff - but concentrations over a certain percentage in green is actually flammable! :newburn:

Yea, better to go at a higher concentration than take a risk.

God mercy jesus I hope not. I just completely redid my cooling system with it, a new thread is in the works talking about it.
your perfectly fine, shop im at, we only use the prestone...
If the green stuff has all of these abrasives in them, then why dont cars that take the green stuff have the problems that you are talking about in the dexcool cars. This is what Im saying, in the cars that take the green stuff, the coolant is in contact with the same type of rubber and plastic conponents as the dexcool cars, now maybe not in the same location, but somewhere in the coolant system both types of cars coolant parts are exposed to the coolant one way or the other, so if I use the green in my dexcool car wont i run the risk of the problems everyone else faces with the green coolant cars? You get what im saying? Just to me in my mind all cars coolant systems are basically the same and your going to have the same problems with the green stuff in either type of car. i think thats what im trying to say.
ahhh young grass hopper, take a 96 3800 (3.8l v 6)apart, and take a 94 3.8l apart... whats the difference?? the plastic and rubber im talking about, the old style (3.8) lower intake has a graphite gasket... the 3800 (new 3.8l) has a plastic and rubber intake gasket that doesnt get along with the green stuff... that is your difference...

I am amazed. Lets see, DEXCOOL has a problem with oxygen? Then waht is water? Don't we need water for the right mix here? What is water? 1 atom and 2 atoms of hydrogen. If this be the case how do you stop DEX COOL from mixing with oxygen? And heat,isn't that what we are dealing with here? And it makes no difference what the heat is set on. Unless you have a heater control valve in the system the water flows thru heater core at the time. When you have heater control valve it closess only during AC request. Your heat blend air door isn't doing anything to the flow of water. A proper maintain coolant system always work the best. Water that we put into car has other elements in it such as iron. Keeping systems service every year will save you lots of problems.

Dexcool doesn't have a problem with oxygen directly, the problems lies within the way that the system acts when oxygen is introduced. The standard green antifreeze is affected by air getting in the system as well, the difference being that it doesn't have the sludging problem.

All antifreezes must be an alkaline mixture to protect the system from electrolysis, the additives are what makes the coolant alkaline. The coolant is much more alkaline than what is needed to protect the system, this is because as the corrosion inhibitors neutralize acids formed anytime that something "attacks" the cooling system, the alkalinity of the coolant is reduced. The extra alkalinity, there to expand the useful life of the coolant, is called reserve alkalinity.

When air is introduced in to a cooling system, the air and water mix with metal, and causes corrosion in the form of rust.

Wikipedia defintion of rust:
"Rust is the substance formed when iron compounds corrode in the presence of water and oxygen. It is a mixture of iron oxides and hydroxides. Rusting is a common term for corrosion, and usually corrosion of steel.

Iron is found naturally in the ore hematite as iron oxide, and metallic iron tends to return to a similar state when exposed to air, (hydrogen, oxygen, nitrogen, etc) and water. This corrosion is due to the oxidation reaction when iron metal returns to an energetically favourable state. Energy is given off when rust forms. The process of rusting can be summarized as three basic stages: The formation of iron(II) ions from the metal; the formation of hydroxide ions; and their reaction together, with the addition of oxygen, to create rust.

Iron is the main component of steel and the corrosion of steel is observed more frequently, since iron is rarely used without alloying in the present day.

When steel contacts water, an electrochemical process starts. On the surface of the metal, iron is oxidised to iron(II):

Fe → Fe2+ + 2e-

The electrons released travel to the edges of the water droplet, where there is plenty of dissolved oxygen. They reduce the oxygen and water to hydroxide ions:

4e- + O2 + 2H2O → 4OH-

The hydroxide ions react with the iron(II) ions and more dissolved oxygen to form iron oxide. The hydration is variable, however in its most general form:

Fe2+ + 2OH- → Fe(OH)2
4Fe(OH)2 + O2 → 2(Fe2O3.xH2O) + 2H2O

Hence, rust is hydrated iron(III) oxide. Corrosion tends to progress faster in seawater than fresh water due to higher concentration of sodium chloride ions, making the solution more conductive. Rusting is also accelerated in the presence of acids, but inhibited by alkalis. Rust can often be removed through electrolysis, however the base metal object can not be restored through this method."


In a cooling system this rust is neutralized by the corrosion inhibitors, reducing the system's reserve alkalinity, which in turn shortens it's life. (This is why in real world applications, Dexcool doesn't last 150,000 miles) The degradation of coolant in constantly being accelerated as new things are introduced into the system. The suspended rust particles, increase the conductivity of the coolant, accelerating electrolysis. Not only does electrolysis remove particles from the aluminum componets of the system, but it also removes some of the rust from the componets containing iron. The suspended particles have an additionial negative effect in dexcool systems due to the OAT attacking, and clinging to the suspended particles, causing a thick, rust colored sludge. As the OAT is drawn to the sludgy masses, it offers less protection to the system componets, allowing more rust to form, further accelerating the process. All this is why it is crucial to maintain your system and keep the coolant fresh.

also I find city driving shortens the life as well.

I think what blazee is saying is, dont try to be smart not here, you wont win.

Go Blazee, I couldnt have said it better myself, thankfully theres wikipedia

I am amazed. Lets see, DEXCOOL has a problem with oxygen? Then waht is water? Don't we need water for the right mix here? What is water? 1 atom and 2 atoms of hydrogen. If this be the case how do you stop DEX COOL from mixing with oxygen? And heat,isn't that what we are dealing with here? And it makes no difference what the heat is set on. Unless you have a heater control valve in the system the water flows thru heater core at the time. When you have heater control valve it closess only during AC request. Your heat blend air door isn't doing anything to the flow of water. A proper maintain coolant system always work the best. Water that we put into car has other elements in it such as iron. Keeping systems service every year will save you lots of problems.
think about exactly what your argument is... what is water? you are correct, 2 hydrogen and 1 oxygen, if i toss a match into the water (or hold it just above the surface, because its the fumes of the liquids that are flammible not the liquids themselfes) thers no raging infurno of hell, even though oxygen supports fire, and hydrogen makes one hell of a boom if contained, thats because when you have an element, the proporties change from the original chemicals

I think what blazee is saying is, dont try to be smart not here, you wont win.

Go Blazee, I couldnt have said it better myself, thankfully theres wikipedia

Who is being smart?

Who is being smart?
I think that he was talking about rksnc's post and my response to it.

I think what blazee is saying is, dont try to be smart not here, you wont win.

Go Blazee, I couldnt have said it better myself, thankfully theres wikipedia

He doesn't have to "try" to be smart, he "is". I've read a lot of his posts and know for a fact that the man knows his shit. All the facts that he posted were true. He was simply questioning some things that didn't seem to make sense. So, I tried to explain it in a little more detail, because the information in a lot of other posts on this subject is a little general, and not very specific.

And I agree. With all the facts that are out there, the bottom line comes to, how well you maintain your cooling system. Yes what I was reading in other replies was so much about air in the system. And my point is air is a part of water which is require in the coolant system. While I have a shop and work on theses cars every day I don't always understand all the agruments on the subject. But I can say without a doubt, a properly maintain cooling system will bless you with less problems. I am sure iron in water varys from town to town. Other elements in the water will vary too. But everyone can maintain there cooling systems and prevent problems just the same way you would change your oil. It is not that I am trying to be smart,I just think people forgot what the first question was all about and got off topic kinda.

LT, I just read an 04 post about replacing the radiator cap to solve the sloshing noise and did that, but it didn't do anything... actually it may even be noisier. I also flushed the system and replaced the thermistat because it's a 96 I bought used and has 130K miles on it now and I want to preserve the cooling system if I can. Anyway, my real question is.... how sure of a thing is this thread about parking on a hill and basically bleeding the air out of the heater core by having the air flow to the highest point?

Perfectly said.

Best to use ramps and get a good difference in height.

Allw the engine to warm up with the rad cap off and keep the rpms around 2000 so the air can be forced out.

Thanks to those who posted about air being in the system. I had a sloshing noise and never knew what it was. I had a cracked radiator, but never put the two together. filled it full and noise is gone. Ok to my question.

Does it matter which way the coolant flows thru the heater core? thanks

ok, as i said in post number 9 i beleve, the green stuff has a different base from the Dex cool, the green likes to eat away at that plastic rubber intake gasket, and you will eat through the seal with green... and to get brown sludge in a Dex system, your 97 was not taken well care of, Dex cool sludges up when it is mixed with oxygen and exposed to heat (will do it in just oxy. but the heat speeds the process up) keep a good rad. cap (factory ones are shitty) on the dex cool and keep it toped off and you will have no problems with it

I too replaced dex-cool with the green stuff in my 96 blazer, and now have a leaking intake manifold. Should I go back to dex-cool (which I hate) or specify a green anti-freeze friendly gasket? It has a 130K miles on it, should I replace the CPI, while I'm at it?

After 130k I would not be suprised at the leak. Replace gasket, you will find the gasket failure and be able to see what happens to them over time. As for the antifreeze put what ever you want. Change it every year and keep mixture correct with water and antifreeze. I would not change CPI until the time comes that it is needed. And yes they do have better gaskets sets available theses days, wouldn't hurt to ask.

Ok. I'm new at this so forgive me, I found this thread closest to my problem, I have a 94 S-10 Blazer that needs the heater core replaced, need to know how to take the dash out to get to the heater core...can you help please???:banghead:

Geez, after reading the initial couple of posts (as I have heard the 'sloshing' noise, I decided to read the rest......whew.....chemistry...lol......
Thanks for the tip. I live in WV, so I know there just might be a hill I can park on :cwm27:

Well even though this thread is over two years old.......

I simply used a floor jack to lift the front of my truck and it worked just fine. Still use the same method whenever I open the coolant system.

Ummm, how do I keep the engine at 1500-2000rpms and watch the coolant level at the same time?

A penny placed between the throttle stop bolt and throttle plate linkage will set it at about 1200rpm

I know this is late but I am gona throw my two cents in. The reason air is the bad guy in a cooling system is that air pockets are areas in the system where there is no coolant next to bare metal and thus less heat transfer and higher engine temps. Of course this also accelerates corrosion due to introducing air into the chemical equation. Correct me if I am wrong, just my thoughts.

No, you can't do that seeing you will need both hands and you will need to hold it open for 10-15 minutes sometimes.

I suggest a piece of wood under the gas pedal to keep it open and constant.

Hmmm... try to get someone to help you? The piece of wood is a good push! :cool: