Question of cooling system design theory,I-5 engine

Tue Apr 12 12:07:25 PDT 2011

Here is an example of the valve I'm thinking of:
http://cgi.ebay.com.au/Heater-Valve-Tap-Holden-V6-Ute-Statesman-Monaro-1991-06_W0QQitemZ130491090171QQihZ003QQcategoryZ33548QQcmdZViewItem

I google imaged "GM four way heater valve" and got a bunch of hits. Looks 
like it is vacuum controled, so it will go right in to most Audi's as long 
as you don't have the old/base model A/C panel with cables.

http://www.ls1tech.com/forums/conversions-hybrids/1319726-bypass-type-heater-valve.html

In the above link the one shaped like an H is the one I've seen before.

-Cody

--------------------------------------------------
From: "Cody Forbes" <cody at 5000tq.com>
Sent: Tuesday, April 12, 2011 3:01 PM
To: "Andrew Dickinson" <amdickinson at rogers.com>
Cc: <quattro at audifans.com>
Subject: Re: Question of cooling system design theory,I-5 engine

> I don't have anything too useful to add other than a note that GM made a 
> 4-way heater valve in the mid 90's used on the LT1/LT4 and LQ (truck) 
> equipped vehicles. Picture four hose fittings and a 2 way valve (forget if 
> it's cable or electric). In position one the coolant flow was routed 
> through the heater core and the bypass blocked. In position 2 the bypass 
> is opened and the heater flow is completely blocked off. Would be an 
> elegant solution to impliment.
>
> -Cody (mobile)
>
> On Apr 12, 2011, at 1:20 PM, Andrew Dickinson <amdickinson at rogers.com> 
> wrote:
>
>> Hi Tony:
>>
>> I have experienced similar issues on the 5k/2c cars.  I have thought of
>> installing a set of valves to (A) Isolate the heater core, and (B) 
>> connect a
>> by-pass when the core is shut off.
>>
>> I have also pondered the constant flow.  I can't see a German engineer 
>> allowing
>> hot to flow when it should not UNLESS the idea is to keep some small 
>> amount
>> flowing to prevent corrosion.  I discounted that idea and actually plan 
>> to
>> install the multi-valve set up.  I have even thought of ddraining the 
>> core
>> during summer months but I am not sure that would be more or less 
>> beneficial.
>>
>> That's my $0.02.
>>
>> cheers;
>>
>> Andrew
>>
>>
>>
>> ________________________________
>> From: Tony Hoffman <auditony at gmail.com>
>> To: quattro at audifans.com
>> Sent: Tue, April 12, 2011 1:02:26 PM
>> Subject: Question of cooling system design theory,I-5 engine
>>
>> Fellow Q-heads,
>>
>> I have a question of theory as I'm working on the A/C system of my '86 
>> 4000
>> Quattro.
>>
>> Firts, a little background. I live in Houston, where we already are 
>> seeing
>> 90 degree highs :( So, since my A/C compressor dies at the end of last
>> summer, I've decided to upgrade while I'm in there. I have installed the
>> rotary compressor from a 90Q, which also requires the lines, brackets, 
>> and
>> Oil filter adapter. All said and done, the system is putting out 44 
>> degrees
>> from the vents at 80 degree outside temps. Pretty good, for what I've 
>> seen
>> so far. I've never been able to get it below 40 with the old setup. If I 
>> had
>> the old setup just as it is now(I'll go over those details in a minute) 
>> it
>> would be putting out somewhere around 52-55 degrees. So, I'm pretty 
>> pleased.
>>
>> However, in every 4000Q I've owned or driven recently, even with the 
>> heater
>> all the way off (verified under the hood against the stop) the heater 
>> never
>> quits giving out slightly heated air. I've replaced the heater valve on
>> several of them as well. This current one will be replaced, as I have a 
>> new
>> one here, but hasn't yet.
>>
>> Looking at the coolant routing, it appears that the heater core runs are
>> sort of a "bypass" of sorts for the thremostat. So, if that's the case,
>> maybe it isn't designed to ever shut off completely?
>>
>> So, here's the question, if I completely shut off that coolant flow, does
>> that create hot spots in the cooling system or engine. I really can't see
>> how it could, but I want to make sure.
>>
>> With the old system, I did have a set of pinch pliers designed to stop 
>> flow
>> through rubber lines when you are working on them. Examples would be when
>> you take a fuel hose off the pump, but don't want to drain the tank. I 
>> did
>> that all last year, as that was the only way to get the temp from the 
>> vents
>> below about 55degrees on hot days. I did not experience any sort of
>> overheating, nor was anything damaged that I know of. But, I've got a 
>> valve
>> setup that I'll be adding to permenantly shut off the heat during the
>> summers, and I just want to make sure I'm not going to stop the flow that
>> may be engineered into the cooling system.
>>
>> As always, TIA,
>> Tony Hoffman
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