troubleshooting oil temp sender?

Where do I start with troubleshooting an intermittent temp gauge?
If the connections are clean and tight, should I remove the oiltemp sender and heat it with something to see what happens in the cockpit? ideas?
912 80 horse steam gauges.

Wheels,

I had an oil temp sensor on our 912ULS get sick after about 3 years of service. It made its self known by intermittently reading zero, then going back to doing its job. Got worse with time. Been a while now, but, I believe the sensor has a resistance value that can be measured to determine if it works or not. This was for the "Quad Gauge" and the sensors that came with it, not the rotax sensor.

If you happen to have the original installation documentation, might have the resistance values there.

Some how or other I decoded that it was the sensor, not the gauge, replaced it and all has been well ever since.

Sincerely,

Dave S

I believe Dave is spot on with this issue - assuming you also have the quad gauge. I have had several sender failures over the years.

The sender consists of the brass screw in housing enclosing a thermister of appropriate value.

I was able to locate the right thermister and have rebuilt the senders. I do it a little differently than I believe they do and they seem to be more reliable.

I checked Mouser where I found the thermister and no go. They have it listed on a direct search, but ten weeks for delivery and they want a bunch ordered. I then spent some time and found it on Allied. For anyone that might be interested the link - http://www.alliedelec.com/search/pro...x?SKU=70181396

Thanks for the replies, I will use the link and order a thermister. I am just hammering away at the little things and waiting for some hardware to reinstall the wings and tail. Then i will do some fiberglass work and she should be ready. Thanks for the help. I'm grateful for your quick and comprehensive replies.
Wheels

I think the trick for longevity is to eliminate the heat shrink over the soldered connections. What I did was to dip the thermister with soldered leads in 5-minute epoxy as an insulation barrier and after that has cured trial fit it in the cleaned out housing. Then fill the housing with epoxy and drop in the thermister assembly and let the epoxy cure. This way any vibration on the lead wires won't travel down to the soldered connection. Up near the front of the engine, the leads are constantly in high air flow.

I had a similar problem with a westach gauge and sender. I replaced the sender a couple of times (would work for a few months). I had checked the ground wire (the builder had spliced 2 together) but it checked ok. When I took out the sensor and heated up, the gauge would move, but had quit completely when installed. Long story short, I finally talked to westach tech and he said the ground wire could seem to check ok, but if it was intermittent or not a really good connection, the gauge would search for another ground and not work normally. I completely re-did the ground wire connection and it has worked since (couple yrs). I figure the only reason it worked (temporarily) when I first installed a couple of senders was because I had "fiddled" with the ground. This may not be your problem, but I thought was worth putting out there.
Paul Perry KFIV 912ul