Date:         Tue, 19 May 1998 14:51:03 -0700
Reply-To:     "harald.nancy" <harald.nancy@MCI2000.COM>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         "harald.nancy" <harald.nancy@MCI2000.COM>
Subject:      Re: Lowering Coolant Pressure for Headgaskets
Comments: To: Vanagon@VANAGON.COM
Content-type: text/plain; charset=ISO-8859-1

Mark B. Magee wrote:
>  Running a cooler temp thermostat can work against you. Remember, the
entire
> Digifant system is reliant upon 195 deg F water temp for proper (ops
normal)
> feedback to the ECU. Anything lower than this and the ECU would try to
> compensate by for instance changing ignition timing to achieve the
desired or
> anticipated O2 temp.
> Now there should be some window of float that are acceptable to the ECU,
I
> don't know what those are, but I would be careful changing thermostat
temp
> ratings in any Electronic Fuel Injected engine, for it has a potential to
> introduce a "feedback mechanism" of correction back to what the ECU knows
to
> be the norm.
> Additionally, lowering coolant temps and pressures would have little
bearing
> on the head gasket issue. The issue is the corrosion, not pressure. And
the
> pressure comes from the other side in a failure, that is the combustion
side.
> ><>     ><>     ><>     ><>     ><>     ><>     ><>     ><>     ><

Yes, lower temperature definitely can work against you.
But the change here is pretty minimal.
The original thermostat opens at    87 degr. cels. or 188.6 degr.fahrenheit
experimental thermostat opens at  80 degr. cels.  or 176.0 degr.fahrenheit
Those numbers are taken from the parts .
cooling fan cut-in temp for 1st stage = 89 deg cels. or 192 degr.fahrenheit
cooling fan cut-out temp   1st stage = 81 deg cels. or 178 degr.fahrenheit

the 80 deg.cels opening temp of the experimental thermo. matches
the cooling fan cut-out temp. of 81 deg.cels.
Those temperatures are all pretty close.

I am hoping the "Master Brain" doesn't notice the lower thermostat temp.
I haven't noticed any change in driveability.

My reason for the change is longevity of all the plastic and rubber parts
in the cooling system, or maybe just some leftover phobia
from my air-cooled days.
Harald
'90 westy