• CHT gauge probe issue

Posted: **Mon Jan 05, 2015 10:24 am**

Guys looking for some advice. I have Stewert-Warner CHT gauge but have a rochester probe 3080-38. They do not seem to be compatible. Talked with Bryan at Maule and he stated they were not and I need to find a Stewert-Warner probe. Any suggestion on where to find them and or other options?

Jeff

Posted: **Mon Jan 05, 2015 7:57 pm**

http://www.aircraftspruce.com/catalog/i ... probes.php Or you can also just Google EGT Probe or Thermocouple for many more options, but aircraft spruce has what you need....

Posted: **Tue Jan 06, 2015 1:33 am**

How do you know which one will work with the old Stewart Warner gauge? I see the Cessna style one specifically states it will not, but that is the style probe in the engine.

Jeff

Posted: **Tue Jan 06, 2015 7:13 am**

I believe that it will be the straight type "K" Thermo Probe... If you call aircraft spruce with gauge PCN and description of old probe, they can verify for you. Commonly, little airplanes only use the "J" or "K" style probes, and they are not interchangeable.. Was it sparkplug type or bayonet into head?

Posted: **Tue Jan 06, 2015 9:27 am**

The one that is in the Cylinder head is a Rochester 3080 spark plug looking thing. That was in there when I bought the airplane. The CHT always ran high but never over the red line until a couple of months ago. I pulled the CHT probe out and did some trouble shooting Temp on engine is okay it was either the probe going bad, a wiring issue or the gauge. Talked to Bryan at Maule and he stated the plug I had does not work with the Stewart Warner gauges I have. However I don't know specifically what probe I need to work with the Stewart Warner gauge on the O-540 engine. Bryan also stated that they do not make the probes anymore for the Stewart Warner CHT gauge. So any specifics on what I probe I am actually looking for would be very helpful.

Thank you for your assistance,

Jeff

Posted: **Tue Jan 06, 2015 12:28 pm**

I got you beat, when I bought my maule 3 years ago the entire cluster was out of a Cessna. Not one gauge was compatible with the senders, luckily Brian was able to source an original new cluster for me.
Here is the Stewart warner that is installed in my plane, its a 333B and the only place I can find that sells them wants over $235 and for that price I might as well put in a whole new system.
Also I believe they are found on a 60's model Corvair
Good Luck

Posted: **Tue Jan 06, 2015 4:45 pm**

Nick, Thank you that is what I was needing the 333B number off the probe. That is what mine looks like but it is the Rochester 3080. I found one site that did have them but like you said it is $235 for the probe and for that kind of price I might as well spend a little more and put a digital CHT/EGT system in and know I am good for the next 10-20 years.

Jeff

Posted: **Tue Jan 06, 2015 6:42 pm**

Try AirParts of Lock Haven. They are pretty good at matching up probes to cluster gauges.

Posted: **Thu Jan 08, 2015 12:18 pm**

Talked to Air Parts of Lock Haven. $140ish to calibrate my gauge to a new 333B Probe and they need the gauge to sent to them. $140 ish for a new 333B probe. Cost looks like it will be a little over $300 all said and done. Anyone have any ideas on alternatives I am listening. Was exploring a multi function gauge such as JPI EDM or EI. but cost wise they may be a little to far out of my reach right now.

Posted: **Thu Jan 08, 2015 1:50 pm**

It has been awhile since I installed the EDM-700 and the prices have gone up a BUNCH.

Getting in the air for $400 is reasonable. The ability to monitor EGT and CHT on all six cylinders is a really nice, however.

I went cheap and did not get the fuel flow initially, but added it later. Would get it all in one instrument if I had it to do over.

TD

Posted: **Thu Jan 08, 2015 2:49 pm**

Trying to figure out whether I have the Rochester or S/W gauges for future reference. How does one tell? Equipment list just shows a Maule part number.

Posted: **Thu Jan 08, 2015 3:53 pm**

I went cheap and did not get the fuel flow initially, but added it later. Would get it all in one instrument if I had it to do over.

Same here, although nothing in aviation is what I would call 'cheap'...

I'm a big advocate of multichannel CHT/EGT. Without one, and the skill to use it, you are obligated to run well ROP (100 ROP or more) for the engine's safety sake. This eliminates the option of running peak or LOP and missing out on the advantages of this method.

Posted: **Thu Jan 08, 2015 7:34 pm**

A cluster gauge unit set-up with 3 over 3 units is a Rochester unit. 6 gauges in a straight line is a Stewart Warner gauge cluster

Posted: **Fri Jan 09, 2015 4:56 am**

If you look down the front of the gauge at the bottom it will have the name either Stewart Warner or Rochester. Needed to use a flashlight to look at it with it still in the panel.

Posted: **Fri Jan 09, 2015 6:58 pm**

6 in a row is not a guarantee of being Stewart Warner . I have the 6 in a row and my oil psi is a Rochester as I had it referbushed a few years ago.