Temperature Sender Alternative

[setho]

My '66 911 has a 2.7L engine from a 1977....

When I purchased the car, it had gauges in it from a 1968 911. The temperature gauge never worked.

I've installed a set of restored green face gauges and the temperature gauge seems to run backwards and spikes.

I believe that VDO changed the polarity of the senders at some point around 69 or 70. The older style senders are well over $200.

Are there any alternative senders I can try out before pulling the gauge and having it updated to work with the newer style sender?

[Richy]

The polarity of the sending units was not changed , but sometimes the gauge needs to be calibrated to work with a particular sending unit .

[tom1394racing]

I have early temperature sending units. PM me for details.

[ejboyd5]

Read Post # 2 in the refernced thread for a primer on different sending units: http://www.early911sregistry.org/for...erature+sender

[setho]

Thanks for pointing to this one....

So the polarity didn't reverse, but the resistance direction did, which actually makes more sense, as it's a single wire and the sender case itself goes to ground. I had bought a 1K pot during lunch, so I was already headed this way.

A little work to do tonight.

[blucille]

the guy who installed the gauges really should have done this for you.

[setho]

For those following along....

I measured the existing sender to ground, and it's wide open. I didn't bother starting the car and letting it warm up to see readings.

Then I hooked up a 1k pot between the gauge wire and ground. Adjusting the pot to the different temperatures I got:

Gauge Temp / Ohms
-----------------------
140 = 183
120 = 175
100 =160
80 = 148
60 = 130

So it looks like I definitely need the old style sender.

[ejboyd5]

This bulletin is for a 912. I'm assuming same change was made for the 911 sending unit:

[setho]

Replaced with an original (2/66) temperature sender. Nice to see the gauge working properly.