Help ! purge air after coolant change

[Jack W.]

Hi group,

I have a 1993 mazda 323 1.6L. Have just put a new radiator and two new
heater hoses on it. I was told that I should purge air out of the
system after I fill it up with coolant again.

The problem is I couldn't find the valve or bolt for this purpose. I
looked around the thermostat housing and didn't see anything. Or is
the removal of the temperature sensor (which is attached to the
thermostat housing) during coolant refill going to do the trick ?

My buddy who is a shade tree mechanic warned me that I might have to
pay for a new head gasket if I don't purge the air properly. Is he
exagerrating ? I remembered I have done two coolant flush on this car
without purging air afterwards and never had a problem.

Appreciate if some knowledgable persons here can comment on this.

[Karl Kittler]

My only advice is to run the engine. That's what's always worked for me,
regardless of make, model or year.

"Jack W." wrote:

--
"WARNING: Armed with a dangerous mind"

[Nick]

Many cars have this difficulty, including many domestic models as well. A
couple of suggestions I can give:

1. Disconnect a high-mounted heater hose when filling, this will allow
you to add a large amount of new coolant rather quickly. When it overflows
that hose or engine outlet, reattach the hose. This will be more effective
on some designs than others, and I'm not familiar with the Mazda engine.

2. Fill the recovery bottle more than normal. Run until warmed, then
shut down the engine. The cooling system vacuum will draw coolant from the
recovery tank.

3. Make sure that both of the heater hoses are very hot, and if not,
purge air from a convienient location. Patience pays off.

Now, I'll tell you what is by far the best way to go, and it involves a
special tool. Several companies now are manufacturing an "air-lift" type
tool that is extremely effective in allowing for complete filling. When the
cooling system is empty, the adapter is attached to the coolant fill
opening, making a tight seal. Next, pressurized air is supplied to the tool
and a venturi vacuum generator will create a large amount of vacuum in the
entire cooling system.

If the cooling system has a vacuum on it, there will not be any air in the
engine at all!

Once vacuum is attained, the air supply is disconnected, and a valve with
hose allows for drawing new coolant into the engine until the vacuum is
depleted. At that point, the engine is totally full, and there is no
purging to be done.

I have recently used one of these a few times at work and it is great, a
real time saver. I guess that one was about $100 from Snap On (Blue Point)
and it is worth the money. People working on old engines won't find much
value in it, since trapped air is not so much a problem. You however, may
want to purchase one.

Nick

Jack W. <buyw...@hotmail.com> wrote in message
news:6de7f155.0201...@posting.google.com...

[Dave Ingersoll]

I've done many Coolant Flush's to many vehicles...Foreign and
Domestic....I've never really heard of purging air out of the coolant
system...but...i've heard of stranger things...and I've never had a
problem...so tell your buddy that he's just wasting precious time that could
be used joyriding... :)

Dave

"Jack W." <buyw...@hotmail.com> wrote in message
news:6de7f155.0201...@posting.google.com...

[Dean Dardwin]

Dave,

Well then I'll tell you about it! Most service manuals have a procedure for purging all the air out of the cooling system. This is required for a couple of reasons. First, air in the cooling system will overheat the engine. Second, air in the heater will render it inoperative, Third, on some vehicles, air gets trapped around the thermostat and will damage it. Follow the procedure in the manual.  If none is stated, use the old "burping" technique to get of the air.

Dean

[Dave Ingersoll]

I just don't understand that because the highest point on the cooling system is the outlet to the radiator...in which all of the air should be pushed out that way....the only way I can see something like that happening is if for some reason you don't put enough water in it....which you do have to fill it while it's running as the water pump pushes the water inside the vehicle...I went to school for 2 years to repair cars and we were never tought anything about this...and I've been a Mazda Mechanic for 2 yrs.... 

"Dean Dardwin" <d...@dxd.com> wrote in message news:3C481B26...@dxd.com...

[Jack W.]

Dean,

thanks very much for responding to my question. Can you explain a bit
about the "burping" technique that you were talking about ?

Thanks again,

J.

[Dean Dardwin]

Jack,

Sure. Park the vehicle with the radiator neck as high as safely
possible. Use ramps, hillside, etc. Turn heater controls to high heat
and select "heater". Remove the radiator cap when safe to do so. Fill
the coolant recovery jar about 1/2 full. Fill radiator. Start engine an
let idle until coolant starts to spit hard out the radiator neck.
Install cap. Let engine idle until upper radiator hose is hot indicating
the thermostat is open. Turn engine off and let vehicle sit 4-6 hours or
better yet overnight. Check recovery jar. If it is empty, repeat
procedure. If not, siphon off extra coolant in the jar and you're all done.

Dean

[bka...@snotmail.com]

In article <u4fq3q1...@corp.supernews.com>, "Dave Ingersoll"
<inge...@charter.net> wrote:

> I've done many Coolant Flush's to many vehicles...Foreign and
> Domestic....I've never really heard of purging air out of the coolant
> system...but...i've heard of stranger things...and I've never had a
> problem...so tell your buddy that he's just wasting precious time that could
> be used joyriding... :)
>
> Dave
>

Then why do Hondas have an air bleed screw near the thermostat?

--
To Email me, change snot to hot

[Nick]

Dave,

 

Sounds like this is not a concern for the Mazda line of vehicles, but it sure is for some others.  It is not true that the radiator is always the highest point.  I am mostly familiar with GM products, and there are millions on the road that really require special attention to ensure correct filling or risk serious engine damage. 

 

The whole 2.8 liter and 3100/3400 line of engines all are this way, installed in millions of "W" and "A" cars.  So is the 3800 to a certain extent depending upon what year and model it is in.  Those are very common engines that require special collant filling procedures, but more elaborate systems are in use on vehicles using an "expansion tank" that do not have any filler cap on the radiator at all.  That not only includes many Cadillacs, but also the common "N" cars with 4 or 6 cylinder engines.

 

So Dave, please be advised of these methods, and take them into consideration when working on a car you aren't familiar with.  I also have an associate degree in Auto Service from a local college, and these procedures were certainly covered in some of the classes I had.  It suprizes me that you weren't exposed to this issue in your training, but since you don't encounter it at your job, I can understand how you might have placed greater importance on learning other things.

 

Just keep this in mind if you ever work on a GM (and likely many others, like Ford's 2.5l) car at work or otherwise.  I have worked on a few imports from time to time at the GM dealership, and I'm sure you might get a GM sooner or later.  (Unless you are writing from Japan).

 

Good Luck,

 

Nick

 

P.S.:    This issue has been covered recently in many of the tech magazines, check out www.underhoodservice.com and "Search Back Issues" of Underhood Service. 

"Dave Ingersoll" <inge...@charter.net> wrote in message news:u4gu4q1...@corp.supernews.com...

[Death]

In article <u4gu4q1...@corp.supernews.com>, "Dave Ingersoll"
<inge...@charter.net> wrote:
>This is a multi-part message in MIME format.
>
>------=_NextPart_000_0050_01C1A024.C85A1C20
>Content-Type: text/plain;
> charset="iso-8859-1"
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>
>I just don't understand that because the highest point on the cooling =
>system is the outlet to the radiator...in which all of the air should be =
>pushed out that way....the only way I can see something like that =
>happening is if for some reason you don't put enough water in =
>it....which you do have to fill it while it's running as the water pump =
>pushes the water inside the vehicle...I went to school for 2 years to =
>repair cars and we were never tought anything about this...and I've been =
>a Mazda Mechanic for 2 yrs....=20

You must not have worked on many of the newer model cars. Mercedes Benz, BMW,
Volkswagen, Audi, Porsche, GM, Chrysler, Honda, Acura, Toyota, Lexus and Ford
all have a few models that have a specific coolant bleed procedure.

And I looked, and behold a pale horse: and his name that sat on him was Death, and Hell followed with him...

[RWatson767]

>Help ! purge air after coolant change

My Chrysler 3.5 V6 has a port to do this.
Bob AZ

[Gordon Wedman]

Heck, my old '69 Alfa Romeo had a specific procedure for bleeding air out of
the system. First you removed a bleed screw on the water pump until water
came out and then you opened a petcock on the cylinder head. Then I think
you filled the overflow reservoir and ran the engine till hot and then
topped up the reservoir after it was cool again. Can't remember if you did
anything with the heater controls.

"RWatson767" <rwats...@aol.com> wrote in message
news:20020120200427...@mb-ba.aol.com...

[George]

This is a problem for a lot of cars today. Honda recommends raising the
right side of the car as far as possible to help purge the air out of
the system. Even though the radiator cap is the highest point there are
many areas in the engine that will trap air and air will not dissipate
the heat and can cause super heated areas. There are now tools available
that create a vacuum in the cooling and heater system. You then close a
valve and insert the hose in your coolant mix. When you open the valve
coolant is drawn in to the entire cooling system. Since you sucked out
all the air with a vacuum the system is completely filled with no worry
of hot spots. Most toyotas will overheat before the thermostat will open
if this or another way of purging air is not used.
George

[Death]

I've never read in any printed Honda factory service manual that says to raise
right side of vehicle. Can you be a little more specific on year, model,
engine? Again which Toyota models are you speaking of? Tell me in which manual
it says this.

[hugh...@bigpond.com]

Mate I have been a mechanic for 50 years, And the best advise anyone will give you is: "READ THE MANUAL" Thats why they make the manuals! And same goes for all cars bikes planes. If in doubt read he manual. Hope you get it sorted out. Have a good day. :)

[Sanity Clause]

<hugh...@bigpond.com> wrote:

> On Friday, January 18, 2002 at 9:26:24 AM UTC+10, Jack wrote:
>> Hi group,
>>
>> I have a 1993 mazda 323 1.6L. Have just put a new radiator and two new
>> heater hoses on it. I was told that I should purge air out of the
>> system after I fill it up with coolant again.

> Mate I have been a mechanic for 50 years

Should I point out that the original post was over 15 years ago, and "Jack"
has probably sold that car, and bought and sold 5 others in the meantime?
Nah, I won't bother. That would be silly. :)