Revisiting exhaust probe failure

[Joe Larussa]

So I just replaced for the third time in 400 hours the exhaust temp probe on cylinder number 2. Each time checked wires, connectors and whatnot. The only thing that fixes it is a new probe. Thoughts?

[carusoam]

Pics of the old probe?

Unsupported wires vibrate until they break…

EGT sensors are in a really harsh environment… they erode slowly…

When they are TIT sensors they may erode in the lifetime of the turbo…

An ordinary EGT… sees less than 1/4 the stress that a TIT will….

Expect that it’s not the sensor wearing out… in a normal fashion…

Best regards,

-a-

[Yetti]

Pics of how your wires are routed.     Usually the routing or install, not the probe

 

[Guest]

What brand of engine monitor?  EGT probes don’t like to have their wire leads bent too close to the stainless steel tube, the wires can be easily damaged.

Routing and security are important.

Clarence

[Joe Larussa]

1 hour ago, M20Doc said:

What brand of engine monitor?  EGT probes don’t like to have their wire leads bent too close to the stainless steel tube, the wires can be easily damaged.

Routing and security are important.

Clarence

It’s a JPI EDM 830. Here’s a pic of the probe. 

[carusoam]

Is that eroded all the way though?

Lets see if @Jeev has seen any of these before… (JPI EGT probe issue)

Best regards,

-a-

[takair]

2 minutes ago, Joe Larussa said:

It’s a JPI EDM 830. Here’s a pic of the probe. 

The probe is surprisingly dark, like it is running very rich?  Don’t know why that would cause it to fail, but the probes I see usually look grey.  What do the plugs in that cylinder look like?

[Joe Larussa]

12 minutes ago, carusoam said:

Is that eroded all the way though?

Lets see if @Jeev has seen any of these before… (JPI EGT probe issue)

Best regards,

-a-

Not eroded all the way through. I’m thinking perhaps pulling the probe scratched off some of the black stuff.

[Joe Larussa]

14 minutes ago, takair said:

The probe is surprisingly dark, like it is running very rich?  Don’t know why that would cause it to fail, but the probes I see usually look grey.  What do the plugs in that cylinder look like?

I haven’t personally seen the plugs in a year or two. I do lean aggressively on the ground and in the air.

[takair]

Just now, Joe Larussa said:

I haven’t personally seen the plugs in a year or two. I do lean aggressively on the ground and in the air.

It just looks darker than I normally see.  Wondering if you have something unusual going on with that cylinder.  Still doesn’t explain what’s going on, but maybe a clue…. Might check the plugs to see if that cylinder is a stand out.

[Joe Larussa]

Can a probe be tested? This engine has about 400 hours on it in 4 years. 

[carusoam]

What were the indications that the probe failed?

One test… swapping it with a different probe… If the problem goes with the probe… bingo!

If the problem is related to the wires between the probe and the instrument…. A different probe won’t make any improvement…

New probes just don’t fail very often…

The blackened sheath… is pretty much armor plating… inside, is a pair of TC wires welded together at the tip…

The wires themselves aren’t very robust… hence the armor…

If a probe keeps failing in the same exhaust location…. The concern for that exhaust tube would be increasing…

 

Want to post some JPI data?

Best regards,

-a-

[carusoam]

To actually test the probe…

connect a sensitive volt meter to it…. In the range of micro volts… as you heat the sensor… the volts increase…

There is a standard voltage reading for the type (K) of sensor in a bowl of ice water, and another reading for it in boiling water…

Best regards,

-a-

[Joe Larussa]

7 minutes ago, carusoam said:

What were the indications that the probe failed?

One test… swapping it with a different probe… If the problem goes with the probe… bingo!

If the problem is related to the wires between the probe and the instrument…. A different probe won’t make any improvement…

New probes just don’t fail very often…

The blackened sheath… is pretty much armor plating… inside, is a pair of TC wires welded together at the tip…

The wires themselves aren’t very robust… hence the armor…

If a probe keeps failing in the same exhaust location…. The concern for that exhaust tube would be increasing…

 

Want to post some JPI data?

Best regards,

-a-

The readings on the 830 starting going crazy, then failed probe comes up on the screen. I had this happen on my stock exhaust as well as my Powerflow. Changing the probe immediately fixes it for about 150 hours 

[PT20J]

Have you discussed it with JPI? They have pretty good tech support in my experience. I would want to know exactly what kind of failure causes a FAILED PROBE annunciation. There is probably a clue there. Is the EGT on this cylinder different than the others with a new probe? Does it change over time before the probe fails?

Skip

[Joe Larussa]

15 minutes ago, PT20J said:

Have you discussed it with JPI? They have pretty good tech support in my experience. I would want to know exactly what kind of failure causes a FAILED PROBE annunciation. There is probably a clue there. Is the EGT on this cylinder different than the others with a new probe? Does it change over time before the probe fails?

Skip

I have not called JPI. I guess I should. All indications are normal then it spikes and goes to red, then probe failure indication. Cylinder head temp rock solid. I can clear it out on the 830 and it’s fine for a while.