________________________________
 > From: mark drillock <mdrillock@COX.NET>
> I wanted to test some more but my wife was headed home and used car
> parts are not welcomed in the kitchen when she is there too.
�
I set up my experiment in the kitchen after dinner when wife and kids are in bed. I spent the evening measuring the VDO dash gauge accuracy compared to the resistance calibration table published by VDO. Instead of a temp sender I used a variable resistor set to different values. Result below is given separately for a rising and falling temp, since they differ substantially.

VDO Vision gauge Part#310 220 002

True�� Gauge Reading
���������� Rise� Fall
�� 180�� 161�� 167
�� 220�� 210�� 219
�� 260�� 246�� 252
�� 300�� 279�� 294

As can be seen this particular gauge reads 10-20F below actual temps when temp is rising (the most relevant case we want to watch for). That seems unacceptably inaccurate to me. Combine this gauge error with sender error and readings can easily be 30F off as I experienced when comparing gauge+sender readings to lab thermometer readings.

Another fault is that the damping of the gauge needle seems to make it stick, so readings on rising and falling temps are quite different. Has anyone else noted this needle sticking?

Dennis Haynes wrote:
> In dash gauges are not high precision devices. I have found that the for the
> VDO gauges the senders for the aftermarket gauges often do not match what is
> used for OEM gauges. Get the correct sender that would be sold with/for the
> gauge you are using.

I agree that achieving one degree precision is not usually that important. In my case I wanted to measure how well the stock VW Diesel oil cooler works at different coolant flows (as reported in another post), so for this experiment accuracy matters.

I also think it is a bit arrogant of the auto parts mfg to sell oil temp kits for typically $40-100 that have reading errors of 10-20F when I can buy a digital BBQ thermometer for $10 that is accurate to a degree or two.

Printed label on the package says: "VDO strives to ensure that every product we sell provides accurate and dependable performance... Every instrument we make is 100% quality inspected. ... Printed in the USA."
Removing the bezel and printed paper reveals a "Made in Malaysia" stamp on the inner housing.

Martin (and '82 Westy 1.9 TD "Poppie")