Old CHT probe replacement

After watching our left engine CHT indicator bounce around the other day, I
decided to pull the CHT probe to look it over. It's ancient, and partially
melted/corroded. So I want to replace it. Here's the problem...

It's not a new style bayonet type two wire probe. It's an old AC (as in AC
Delco) single wire screw in RTD (resistance type device). It looks like a
little spark plug on the connector end and a short thermocouple on the
cylinder end.

It looks similar to the Cessna type probe listed in Aircraft Spruce, but
that sucker is $140 and I don't even know if it would work with our gauge.
(original 1966 Piper single indicator)

Does anybody in the group have a Lycoming IO-540 parts manual handy? I need
to find the current day replacement part number and manufacturer for this
little gem so I can hunt one down.

Thanks in advance!!!

Jim Burns

"Jim Burns" wrote:

It's not a new style bayonet type two wire probe. It's an old AC
(as in AC Delco) single wire screw in RTD (resistance type device).
[...]
Does anybody in the group have a Lycoming IO-540 parts manual handy?
[...]

I didn't find anything about it in the engine manual, but in the Aztec
parts manual, look for "thermocouple" in the instrument panel section
and "cylinder head temperature" in the wing electrical section.

- FChE

On Tue, 30 Aug 2005 20:31:10 -0700, "Jim Burns"
wrote:


It's not a new style bayonet type two wire probe. It's an old AC (as in AC
Delco) single wire screw in RTD (resistance type device). It looks like a
little spark plug on the connector end and a short thermocouple on the
cylinder end.

Call http://www.airpartsoflockhaven.com/

The probe p/n has changed a couple of times, with a different gauge
needed for each probe change. Been awhile since I worked on an older
Aztec, but these guys have been able to come up with what I needed to
get any Piper oil temp/CHT gage up-and-running.

Only issue is, sometimes you need to send them your gage and have them
calibrate it to their probe...

TC

Thanks guys,
I finally found the part numbers, includeing the old AC Delco number and
I'll give Pat at APoLH a call today and see what she can tell me.
Jim