Hello,

Does anyone have the part # for the cylinder head CHT probe in the IO-320 in the PA-30? I've checked both the PA-30 IPC and the Lycoming parts catalog for the IO-320 and can't seem to locate it.

Thanks,
Tim

Tim,

I have the same IO-320s. It is my understanding that the original probe is no longer available. Air Parts of Lock Haven provides another probe and calibrates the gauge and that provides an avenue for repair. It is how I handled the problem when Mike Rohrer at the old Altus shop removed the Twin's probes without my knowledge, permission or approval. He failed to make the repair so I took the plane to PA.

Have to love shops that do unauthorized work. Geez.

I'm pretty sure this is the probe though in Cessna p/n form. Was really hoping these things aren't almost $300 each.

https://www.aircraftspruce.com/catalog/ ... ey=1950379

Tim

Be careful. I think Pat is right - a lot of the older temp probes are no longer available. Air Parts of Lockhaven sells coupler kits (with STC) to convert newer style probes (Rochester mostly) to the old / original factory gauges. Remember that any temp probe is just a thermocouple. Electricity flow thru it and the higher the temp the less the resistance and therefore the more electricity that flows. The gauge is really just an Ohm meter which is scaled to show known temps at known resistance values. For a probe to work it must be correctly calibrated to the expected values on the gauge. If the probe you've found is other than the original IPC spec probe then you can't count on it to give correct gauge readings.

The Air Parts coupler kits go between newer style probes and the gauges. They are basically sets of resistors that can adjust a given probe's electrical output for a given temp to what the gauge is designed to receive. I converted my oil temp bulbs (probes) to the new Rochester style with Air Parts coupler kits and STC. They also re-calibrated my gauges to. I now have very accurate old original gauges but it was a frustrating process. I had to send the gauges, bulbs and couplers back no less than 5 times before they were finally correct. Long story and the subject of another thread on the forums.

- Chalres

Try the part numbers below I got them from the Airparts web site Spruce has both of them in stock at the East store,

Temperature Senders - Series 3080
CHT Probe - 3080-38
Oil Temp Probe - 3080-37

George

 

In case anyone else is curious, the Rochester probes listed above work nicely with the original AC gauges with one of these 82 Ohm resistors installed in line. At least that what the hangar gremlin told me.

http://www.radioshack.com/nte-1w082-10- ... or&start=9

You'll still want to confirm gauge accuracy of course.

Tim