Water temp gauge

[drew at scirocco.cs.uoguelph.ca (Drew MacPherson)]

I installed an oil temp sender in the coolant outlet at the end of the 
head and wired it in to my MFA on the turbo diesel to monitor coolant 
temperature.  Normal operating temperature is at or around 87 C, this is 
the usual "1/8-1/2 needle width above the LED"  I have seen temps as high 
as 94C, fully loaded, with post-turbine EGT's in excess of 900F, but 
generally it does not exceed 90-92C on moderate load, and usually runs 
around 86-88.

There are (at least) 2 versions of the temperature guage that have 
integrated warning LEDs and I have found them to read differently at 
higher temperatures.  The guage that was originally in my 84, as well as 
several other 84-87 gauges that I tested tended to read higher on the 
scale than temperature guages from later clusters.  The earlier guages had 
no distinguishing markings, but the later guages had a temperature printed 
on them (down near the bottom wehre the needle pivots) that was around 
125C (don't remember the exact number.)  Although these later guages would 
read the same at normal operating temps (ie 87 C - thermostat opening 
temp) they would not read as high as the temperature increased moderately 
as the earlier ones would.

Instrument cluster, engine or chassis ground issues will cause higher than 
normal temperature (both coolant and oil) readings.  On the later A2's 
that use plastic coolant manifolds, the senders are all two prong, and the 
ground sides are all grounded at the same point as the instrument cluster 
(under the dash.)  This tends to keep the readings more consistent, and 
less prone to voltage drop when you turn on your headlights etc.

Drew

On Wed, 29 Oct 2003, Chris M Cougill wrote:

> 
> I second the call for a ballpark guide to what the VW temp gauge is
> indicating at its various positions.  Mine rides at 2/3 of the way up on
> the highway, which seems quite high, but my oil temp rarely indicates
> above 105 degrees or so.  
> 
> I, too, wish VW hadn't cheaped out on the temp gauge.  Has anyone added
> an aftermarket gauge w/o eliminating the sender for the dash gauge?  That
> ought to give us an idea of what the factory dash gauge reads, though I'll
> bet there's quite a varaince in the accuracy of the factory units...
> 
> Tks,
> 
> Chris
> cscmc1@eiu.edu
> 
> 
> 
> 
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