Date:         Fri, 26 Jun 2020 01:05:47 -0400
Reply-To:     Gabriel Hourtouat <ghourtouat@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Gabriel Hourtouat <ghourtouat@GMAIL.COM>
Subject:      Re: Coolant Hoses, Complete Set -- Remove and Replace
In-Reply-To:  <f451c504-072c-0b9c-bd56-0df76875b3ba@cox.net>
Content-Type: text/plain; charset="UTF-8"

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.
> >
> >
>