Date: Tue, 20 Nov 2012 08:51:47 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Rear heater control
In-Reply-To: <50AB0C5E.9070504@turbovans.com>
Content-Type: text/plain; charset="us-ascii"
At this point I have yet to pull out a front heater core that didn't show
signs of leakage. They are deigned to be light and thin to transfer heat and
cost as little as possible, not last 20 years or more. I doubt that valve is
so tight that no coolant flows at all when closed. Next long trip feel the
hoses. I'll bet there is some heat on the feed line. Not all failures are
due to someone's fault. I think we see more rear heater core failures as
they are accessible and the leakers are obvious without outside air diluting
the smell.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Scott Daniel - Turbovans
Sent: Monday, November 19, 2012 11:52 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Rear heater control
Greetings all,
I am glad to see people thinking on a deep level about what goes on in a
rear heater core, especially when there isn't any coolant flow through it
for long periods of time.
and...no fighting or barking please !
fwiw, having seen many rotted out vanagon rear heater cores, I strongly
believe that coolant just sitting in the rear heater corecontributes to the
failure of them.
. Add in the factor that some vanagon owners don't even know that heater
core is there, or how to operate it intelligently,etc......and the end
result is leaking heater cores when coolant just sits in them for
yearswithout circulating............. in my experience.
I had not thought to much about how temperature affects degree of solubility
of solids in liquids ..
and it does turn out that temp is a factor. Generally ..higher temp allows
solids stay in solution. Found this in a quick search.
http://www.medicareconsumerguide.com/
I'm a bit like this myself ...I may not always know the pure 'why' of what
works well ....but I know 'what' a good solution ( pun not intended ) to a
problem is - such as keeping some fresh coolant flowing in the coreback
there.
Here's how I think about it ...
Anti-frz coolant mixtures have addtives and chemiicals in them to prevent
corrosion.
Those wear out over time.
Naturally,a heater core is disigned to have a lot of contact between the
coolant in it and the metal tubes and fins.
Since the corrosion-resistant properties decline over time...
there ya go ....coolant sitting in the core back there is rough on it.
Heck ..
we see 15 or even more leaking rear heater cores for every bad front on.
Of the whatever.....few hundred vanagons I've worked on ...I've replaced
one or two front heater cores..
and seen dozens of rear ones leaking.
I don't think particles falling out of solution has much if anything to do
with eating of metal, or the seal between the metal tubes and fins and the
body of the unit.
It's the decline in corrosion properties of the juice sitting in thereover
the years.
Particles that fall out of solution reduce how well you can get heat out of
the heater core of course..
my 41 year old Mercedes car front heater barely works compared to what it
once did ..
doesn't leak though.
All I can say is..
keep your vanagon rear heater valve at least partially open year round !
I will also say it's not so much 'what' you use for anti-frz ..it's 'how'
you use it ..
that you use a quality product...that you don't leave it in there forever (
you never get all of the old out anyway ) ..
( and I have mentioned my half cup of water soluble oil trick many times of
course. That flat works. I just do not get corrosion in any of the cooling
systems of my 15 or so cars and vans. )
no fighting or barking please .
scott
www.turbovans.com
On 11/19/2012 4:13 PM, Alistair Bell wrote:
> oh for goodness sake's Dave, you never get challenged at home? Does asking
you to explain your hypothesis constitute an insult?
>
> :)
>
> I'm not getting excited, just curious if you know what comes out of the
coolant when it it left standing.
>
> But how about a little thought expt, ok? Suppose stuff does fall out of
solution in the isolated, and now cool, rear heater. That stuff would be
limited to the amount in solution in the volume of the isolated coolant,
lets be generous and say 1 litre. And why does it fall out of solution?
Because it is cooler than it was when it picked up the solutes (whatever
they may be) in the first place.
>
> Now lets imagine the heater not being isolated, but rather it being used.
In this scenario all the engine coolant will at some time pass through the
heater. And because the heater works by transferring heat from the coolant
to the air in the van, we can conclude that the aluminum fin/coolant
interface will be cooler than the engine/coolant interface, right?
>
> So now we have 17 litres of coolant and its dissolved stuff passing
through a cooler region and this temp drop must cause some of the solute to
drop out of solution. It might not drop out at the same rate as it would if
the coolant were cooler (mind you ii does get cooler in the heater when the
van is not running) but on the other hand the entire coolant supply is
passing through the heater.
>
> So I would say you would see more ppt. in the heater that was in the loop
than a heater that was out of the loop.
>
>
> Look at the radiator, I have. It gets clogged up over time with stuff
> and it doesn't get turned off in the summer does it? :)
>
> alistair
>
>
> On 2012-11-19, at 2:28 PM, <mcneely4@cox.net> wrote:
>
>> ---- Alistair Bell <albell@SHAW.CA> wrote:
>>> what the heck exactly do you believe is suspended or dissolved in the
coolant that will drop out of solution, or settle, or what ever, upon
standing?
>> Corrosion products? Not all coolant is created equal, and certainly not
all water is chemically pure. I use distilled water, but it is not reagent
grade. Many people use tap water, which in some parts of the country is
pretty rough stuff. We all know that the waterboxer cooling system is
corrosion prone. Some folks just use whatever coolant is on the shelf and
cheapest.
>>
>> Good grief, Alistair, there is no need to get excited. If I am wrong, I
am wrong. A little politeness rather than insults thrown at me because you
perceive me to be more ignorant than you would be appreciated. Does it do
any harm if someone leaves the valve set in "winter" position in summer? I
actually don't have a rear heater, so maybe your complaint is with those who
do and advocate the winter setting in summer.
>>
>> I was just trying to offer a rationale, one that I am still not convinced
is wrong, given all the possible variables in the mixture present and
operating conditions. If chemical processes were not possible in the
cooling system, manufacturers of vehicles and coolants would not go to all
the trouble they do to minimize the possibility. For example, VW recommends
a phosphate free coolant, but many coolants sold in the market are simply
labeled as being compatible with all vehicle makes and all coolant types.
Whether they are phosphate free or not is a part of "let the buyer beware."
Yet I have seen advocated on this list that any ethylene glycol based
coolant is suitable for the waterboxer.
>>
>> mcneely
>>
>>> alistair
>>>
>>>
>>> On 2012-11-19, at 1:05 PM, <mcneely4@cox.net> <mcneely4@cox.net> wrote:
>>>
>>>> Alistair, I do not mean such suspended materials as the silt in a
sample of river water, but rather chemical suspension including solution.
My term was precipitate, not settle. In a perfect world, I would not expect
the dissolved materials in coolant to precipitate out, but since they
interact with several different materials in the coolant system, I am not
convinced that precipitation will not take place. I do know that that was
one of the problems some folks had with early generations of the coolant
sold by GM and the brands intended to substitute for it. Maybe you are
correct, that this would never be a problem. Certainly, fresh, clean
coolant solution should behave better than old, contaminated coolant
solution. And maybe flow would not matter. In my system, I have obviated
any problem of static coolant in the rear heater by removing the thing. If
it is a problem, it should apply to the front heater as well, of course.
>>>>
>>>> BTW, when I mentioned to my mechanic recently that I intended to
>>>> flush the cooling system and replace the coolant this winter, he
>>>> asked me why. I said that the coolant was more than two years old.
>>>> He said if I do it, save the coolant and give it to him, that he
>>>> would run it in his vehicles if it looks clean. It does look
>>>> clean, in fact, quite clear. mcneely
>>>>
>>>> ---- Alistair Bell <albell@SHAW.CA> wrote:
>>>>> Dave,
>>>>>
>>>>> my point it that I can't see, or have seen proof, that closing the
rear heater valve will cause any harm to the heater, given that the van has
a good charge of coolant. There is no proof that anything will precipitate
out as you think it would. What suspended matter is there in the coolant? If
you can tell me that then we can have a discussion. Perhaps take a sample of
your coolant and let it sit for a while and see what drops out?
>>>>>
>>>>> alistair
>>>>>
>>>>>
>>>>> On 2012-11-19, at 12:38 PM, <mcneely4@cox.net> wrote:
>>>>>
>>>>>> Alistair, while I agree that chemical environment matters to
>>>>>> chemical processes, I am not sure that the facts you cite would
>>>>>> prevent precipitation of suspended matter in a static setting
>>>>>> with tiny passages. But, I (like others) have been wrong before.
>>>>>> mcneely
>>>>>>
>>>>>> ---- Alistair Bell <albell@SHAW.CA> wrote:
>>>>>>> Dave,
>>>>>>>
>>>>>>> the comparison you make between a car's cooling system:
>>>>>>> - closed loop, low O2 (if not anoxic), water, ethylene glycol,
>>>>>>> corrosion inhibitors
>>>>>>>
>>>>>>> and a dishwasher:
>>>>>>> - open loop, O2 rich, water, caustic cleaning solution
>>>>>>>
>>>>>>> doesn't warrant much more thought than just how bad an analogy you
made .
>>>>>>>
>>>>>>> :)
>>>>>>>
>>>>>>> alistair
>>>> --
>>>> David McNeely
>> --
>> David McNeely
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