EGT Sensor

[Tooch]

Just wondering, When an EGT probe is going bad, does it usually quit all together of kind of flicker for a while? sometimes going up and down.

 

[D-Dubya]

Depends on the mode of failure. It's not unusual for the readings to jump around when it's about to go belly up. Check for loose connections first, but it's likely that probe is on its way out.

 

[RV-9erA]

Just wondering, When an EGT probe is going bad, does it usually quit all together of kind of flicker for a while? sometimes going up and down.

Yes -- it's very common to have your EGT indication surge higher and then drop to normal in a cyclic fashion, especially while you're leaning. Typical failure of an EGT probe is to go non-linear, especially in the higher temperature range.

 

[GatorsR1]

One of mine started bouncing around erratically (off scale & back to "normal"), replaced it and all was well until a few Hobbs hours later, the other side played the same tune. Up until then I didn't think or know anything about their expected lifespan (in this case, both in the vicinity of 700 hours).

 

[walkman]

Troubleshooting this right now, with both an EGT and a CHT sensor (or multiple).

What is the generally expected life of these probes?

If one or two are going bad, should all be replaced at the same time?

 

[D-Dubya]

If one or two are going bad, should all be replaced at the same time?

You could, but they're not cheap. They're not hard to replace if they fail one at a time, and the consequences of failure are really more of a nuisance and not necessarily a safety of flight issue. It's really just up to you if you want to replace them all.

 

[RV7 To Go]

Troubleshooting this right now, with both an EGT and a CHT sensor (or multiple).

What is the generally expected life of these probes?

If one or two are going bad, should all be replaced at the same time?

I have had a 3 EGT probes go bad in 1400 hrs but no CHT probes. I just changed the ones that went bad (not all at the same time or on the same engine). The first thing to check are the crimps. I have had a couple factory crimps that needed re-crimping and things were ok. That's the first thing I do if I see an erratic or unusual very high reading.

 

[Tooch]

Thanks for the replies. This will be the third one that i will be replacing. Engine has about 500 hrs on it now. EGTs are the ones Dynon sold in 2010. I read here somewhere that during that time, those were crap. Just wanted to make sure it wasn't just the molex connection.

 

[walkman]

You could, but they're not cheap. They're not hard to replace if they fail one at a time, and the consequences of failure are really more of a nuisance and not necessarily a safety of flight issue. It's really just up to you if you want to replace them all.

My concern is "how do you know they are bad?"

If the failure mode is obvious, like it reads 0 or constantly hops around then fine, easy to detect and fix. But what if the failure mode is more subtle, like it starts to read a lower and lower temperature. Would that cause issues when trying to get LoP for example, or does it even matter since we're using differential rather than absolute temperatures?

 

[walkman]

I have had a 3 EGT probes go bad in 1400 hrs but no CHT probes. I just changed the ones that went bad (not all at the same time or on the same engine). The first thing to check are the crimps. I have had a couple factory crimps that needed re-crimping and things were ok. That's the first thing I do if I see an erratic or unusual very high reading.

I don't use the factory connectors, I hate them. I replace with weatherpak connectors. They are a bit bulky, but much better imho

 

[D-Dubya]

My concern is "how do you know they are bad?"

If the failure mode is obvious, like it reads 0 or constantly hops around then fine, easy to detect and fix. But what if the failure mode is more subtle, like it starts to read a lower and lower temperature. Would that cause issues when trying to get LoP for example, or does it even matter since we're using differential rather than absolute temperatures?

The easiest way to determine if a probe is bad is to swap it out with a probe from another cylinder. If the bad readings follow the probe, you've pretty much chased that rabbit down the right hole.

 

[walkman]

The easiest way to determine if a probe is bad is to swap it out with a probe from another cylinder. If the bad readings follow the probe, you've pretty much chased that rabbit down the right hole.

Yeah that’s great when it’s an obvious behavior but doesn’t work, or doesn’t work as well, if the failure mode is more subtle ie reading hotter or colder as it ages

 

[Norman CYYJ]

Yeah that’s great when it’s an obvious behavior but doesn’t work, or doesn’t work as well, if the failure mode is more subtle ie reading hotter or colder as it ages

All egt and cht temps, oat and oil temp should read really close to the same temperature if sitting in a hangar over night.

 

[Tooch]

All egt and cht temps, oat and oil temp should read really close to the same temperature if sitting in a hangar over night.

Yeah, mine does that but when i fly and the temps come up, that’s when i get the erratic readings. That’s why it may be the molex pins. Maybe I will take it out and test it with a blow torch. Heat gun didn’t get it hot enough.