since we are on the thermostat topic, I have a question..

some thermostats have a tiny hole on the top, some don't have it.. so some
people drill a hole about 1/16"...

what's the purpose of the hole and is it a good thing to have it?

thanks

On Sat, Jun 27, 2020 at 9:19 AM Dennis Haynes <d23haynes57@hotmail.com>
wrote:

> Very good. A major problem with cooling system diagnoses is the variables
> of components especially new stuff. You just don’t know what to trust! Is
> the gauge, sensor, t-stat, fan switch whatever? The aftermarket sensors
> especially are always suspect. For infrared scanners there are also
> variables, especially the emissivity of what you are looking at and the
> spot distance-focus of the sensor. Having experience with it when all is
> good is very helpful when diagnosing when something is wrong.
>
> For thermostats keep in mind the primary purpose is to ensure a minimum
> temperature. Then hopefully the response is sensitive enough to maintain a
> given range. At some point the cooling system will be saturated where the
> stat is fully open no more can be done. A cooling system with proper mix
> and pressure should be able to handle temps up to 240F briefly without
> failure.
>
> The next test of that stat is how it does in cold weather. The latest stat
> spec (the F version) addresses the poor warm up performance with the seal
> on the top disk and the delayed opening and then fast response. This was
> needed due to the very large cooling capacity of the cooling system both in
> volume and the radiator capacity along with the heat removal of the two
> heater cores.
>
> Dennis
>
>
>
>
>
> -----Original Message-----
> From: Vanagon Mailing List <vanagon@gerry.vanagon.com> On Behalf Of
> Gabriel Hourtouat
> Sent: Friday, June 26, 2020 11:08 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Coolant Hoses, Complete Set -- Remove and Replace
>
> Problem solved.
> New Tstat removed;
> Old Tstat re-installed;
> (coolant temp gauge needle stays middle of the LED; ECU readout 0.15 V;
> thermoscan of coolant pipe around 85C)
>
>
> On Fri, Jun 26, 2020 at 1:05 AM Gabriel Hourtouat <ghourtouat@gmail.com>
> wrote:
>
> > Mark, Dennis,
> > -Thanks for your comments.
> > -Got some data!
> > -comments and guidance?
> >
> > I think my thermostat wants to keep the engine temp at whatever
> > temperature corresponds to 0.12V on the temp sender!
> > Tomorrow I will change the Tstat using Dennis procedure form 2018.
> > (pasted below the data for reference)
> >
> > Didn't scan the rubber hoses on this go around; but monitored two temps:
> > -"Coolant Temp" signal (using the Shoebox Electronix Monitor, a gadget
> > which outputs the signals seen by the ECU to an LCD screen)
> > -un-calibrated junky thermo scanner aimed carefully at the same range,
> > same spot on steel pipe (scanner resting against the wires in that
> > area, about 1 inch off the pipe)
> >
> > ECU / Pipe / state
> > 0.43 / 56C / just started engine
> > 0.21 / 75
> > 0.18 / 86
> > 0.16 / 91
> > 0.14 / 94 / rad reads 34C
> > 0.13 / 96 / needle on the dashboard is middle of LED
> > 0.13 / 97 / needle at top of LED
> > 0.13 / 99 / needle above LED
> > 0.12 / 98 / needle stable
> > 0.12 / 100 / rad reads 50
> > 0.12 / 100 / rad 73
> > 0.12 / 99 / rad 85
> > 0.12 / 100 / rad 86, fan is ON
> > 0.12 / 98 / rad 84 fan is still ON
> > 0.12 / 98 / rad 83, fan is OFF
> > 0.12 / 101 / rad 83, fan ON
> > 0.12 / 100 / rad 82, fan OFF
> >
> > Driving:
> > ECU stays at 0.12 at all speeds with little variation -bumps to 0.13
> > when the heater goes to full blast, 0.11 when getting off the highway;
> > -In all cases, the readout soon gets controlled back to 0.12.
> >
> > Shoebox Electronix instructions gives some specifications for the
> > coolant
> > temp:
> > above 0.95V when cold
> > 0.17 at Warm idle
> > 0.18 at 30 mph
> > 0.21 at 60 mph
> >
> >
> > changing the Tstat procedure:
> > Do this with engine cold. With system tight you should lose only a
> > small amount of coolant removing the t-stat cover. After you put it
> > back together open the bypass valve on the cover, start the engine,
> > remove the pressure cap, hold engine at 2,000 rpm and top off pressure
> > tank. Replace pressure cap, let engine return to idle and you should
> > be good to go. If the system is working properly it will finish any
> > other air purging on its own.
> >
> > Dennis
> >
> >
> >
> > On Thu, Jun 25, 2020 at 10:48 PM vw_van_fan_Mark <madvws@cox.net> wrote:
> >
> >> If the coolant returning to the waterpump is really 225F then the
> >> radiator fan should be running constantly since that is above the rad
> >> fan temp switch shut-off temp. If the thermostat is working then the
> >> radiator itself should measure hotter than the coolant returning to
> >> the water pump.
> >>
> >> So I would question whether the thermostat is fully working.
> >> If bypass disc isn't closing off the bypass path then some coolant
> >> would be able to skip the radiator and just keep recirculating back
> >> to the pump. Some coolant would still go to the radiator if the main
> >> thermostat disc was opening.
> >>
> >> If you can measure the temp of the large rubber hose to the top of
> >> the thermostat housing and compare it to the temp of the large rubber
> >> hose connecting the lower housing to the waterpump feed pipe the
> >> results should help determine what is happening. Measure the rubber in
> both cases.
> >>
> >> Mark
> >>
> >> Gabriel Hourtouat wrote:
> >> > Celebrations cut short.  Violins start to play...
> >> >
> >> > Is it possible I have a bad Tstat?
> >> > -any opinions and suggestions are MOST welcome...
> >> >
> >> > after more extensive driving around, engine temp is controlled well
> >> above
> >> > what I am used to (IE (bottom 1/3 of the LED)...
> >> > -temperature gauge:  centreline of the needle is about 1 full LED
> >> > diameter above the centre of the LED -temperature scanner reads
> >> > 225F on the return pipe to the water pump
> >> >
> >> > At idle, the coolant fan comes on and controls the temperature at
> >> > this elevated temperature.
> >> >
> >> >
> >>
> >
>