Date: Mon, 7 Sep 2015 09:29:14 -1000
Reply-To: "SDF ( aka ;jim lahey' - Scott )" <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "SDF ( aka ;jim lahey' - Scott )" <scottdaniel@TURBOVANS.COM>
Organization: Cosmic Reminders
Subject: Re: Where is temperature sensor & why does needle drop when
heater is on?
In-Reply-To: <55EDDF1E.70300@williamsitconsulting.com>
Content-Type: text/plain; charset=utf-8; format=flowed
if things are working right ..
turning on the heater ..and thus cooling the engine more, will not
create a drop in the coolant temp gaude indication.
if the t-stat is working right, and the heater removes some engine
coolant heat, the t-stat will close a tiny bit to compensate.
it's job is to only let coolant that is up to temp flow out of the engine.
I'm sure if it's say a 87C stat ...it starts to open a bit before that.
German waterboxer stats come in ..I forget exactly ..I think 77 and 87 C ...
for winter you want the warmer one.
a common misconception for summer ambient temps and load..and value of
t-stat.
putting in a cooler stat doesn't increase cooling ability,
it just lowers the temp at which coolant starts to flow.
If load and conditions dictate that it wants to run at say 105C ..it
doesn't matter if it has a 60 or a 70 or an 80C stat or whatever.
I'd say you are well overdue for a new german t-stat.
also ..I imagine this is an 86 or later waterboxer..2WD with plastic
t-stat housing.
it's not good to let the t-stat cover screws sit untouched for eons ..
it's not hard for corrosion to build up ...
when that happens....or someone made those 4 screws much too tight long ago,
you get a situation where the brass insert/s can just spin in the plastic ..
then you need to grind or somehow cut off the screw hex head ..can get
into a real deleicate project.
those plastic t-stat housings don't last forever, at all.
scott
On 9/7/2015 9:01 AM, Steve Williams wrote:
> Hi,
>
> The problem is that the temperature drop doesn't happen "briefly"... the
> temperature guage stays reading low until I turn off the heater again.
>
> If the thermostat starts opening @ 85C (approx) and is fully open @
> 105C, I'd assume that the 105 is where the "normal" spot on the
> temperature guage. Add the extra cooling of the front heater core, the
> temperature drops and the thermostat should start to close & reduce the
> amount of water flowing to the front radiator, thus increasing the
> temperature of the water circulating in the engine & keeping the
> temperature guage at the "normal" level.
>
> I'm leaning towards the list wisdom about a malfunctioning thermostat.
>
> Thanks for the feedback!
>
> Cheers,
> Steve W.
>
>
>
> On 07/09/2015 10:16 AM, Dan N wrote:
>> I think it's normal behavior. When you open the front heater, cold
>> coolant in the heater core flows to the radiator, warm coolant from
>> the radiator flows to the heater core - an exchange - and you see
>> small dip on the coolant gauge. This will happen briefly until the
>> warm coolant in the heater core reach the same temp. as the coolant in
>> the radiator.
>
