Date: Fri, 14 Sep 2012 11:17:47 -0700
Reply-To: Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Subject: Re: [Diesel-Vanagon] Re: Oil temp gauges,
choices? Using water temp sender + gauge?
In-Reply-To: <50529000.7080207@cox.net>
Content-Type: text/plain; charset=iso-8859-1
Mark,
Thanks for doing the testing. It shows that it is possible to get a reasonable sender - gauge pairing.
I was curious if you or anyone else noticed the sticky needle issue I had?
It is easiest to see when instead of the sender one used a potentiometer (variable resistance) anything around 100-200Ohm is suitable.
To see if it the gauge needle is sticky
1. turn the pot up to near full gauge
2. Then slowly turn down until needle is over a reading (say 260F).
3. Now disconnect wire between pot and gauge. gauge falls to 0. (do not change pot)
4. reconnect wire. See if gauge shows same reading (260F).
If the needle is sticky it will show a smaller value. For me the value at step 4 was 10-20F below.
Same test can be done with regular sensor in water + using a digital meat/bbq thermometer as reference.
First slowly heat the water to boiling.
When VDO gauge reaches each of 120F, 180F mark read the digital temp
Then let the water cool. Again read digital temp when VDO gauge reaches each of 120F, 180F.
Ideally temps should be same, but with a sticky needle they may differ
Using canola oil instead of water one can test the 220 and above readings too.
Martin
________________________________
From: mark drillock <mdrillock@COX.NET>
For fun I just now tested 3 VDO temp gauges and senders I have on hand.
I used a 12 volt battery and a pot of boiling water, at sea level.
The first was a new VDO aftermarket water temp gauge 0-250 F. It was
paired with the aftermarket VDO brand temp sender of the matching range,
sold to me at the same time as I purchased the gauge.
With the sender in rapidly boiling water the gauge read almost exactly
between the marks for 200 and 225 F. A whisker higher than the midpoint,
maybe 215 F? Pretty good I'd say.
Next I grabbed a used VW car oil temp gauge made by VDO and the VW
sender I pulled from the same car when I pulled the gauge. Both are
marked 0-150 C. The sender has the same part number marked on it as the
one you linked to from TBD.
With the sender in rapidly boiling water the gauge read almost exactly
at the 100 C mark, just a whisker below, 98/99? Pretty good again.
Especially for parts pulled from a 25 year old car, with date codes on
the parts indicating they are really that old.
The third set didn't act right. This used 150 C VW car oil temp gauge
read very low when paired with the VDO sender I had it stored with. I
then connected up the sender from the other VW VDO setup and the gauge
now read correctly, near 100 C. Then I got out the magnifying glass and
looked more closely at the odd reading sender. It said 180 C on it, so
no reason to expect it should work right with a 0-150 C gauge. The VW
part number on it had a B suffix, rather than the A of the 150 C sender.
The rest of the number was the same.
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.
Mark
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.
>
>
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