Dynon EGT Probes

Hey there:...

Doing my annual on my Lycoming powered RV-7 and found that #4 cylinder EGT probe was covered in hard-to-scratch-off deposits. This could be why that cylinder EGT registered 100F + higher than the other 3. What brand of EGT probes does Dynon use I'm thinking of replacing all 4 probes while I'm at it. I have emailed Dynon support but have not heard back from the company.
Aircraft Spruce has several offerings but I'm unsure of which ones would be compatable with my Dynon EMS-120.
Does anyone have an answer?

Thanks

Dave
RV-7
C=GCPD

rv7guy2 said:

Hey there:...

Doing my annual on my Lycoming powered RV-7 and found that #4 cylinder EGT probe was covered in hard-to-scratch-off deposits. This could be why that cylinder EGT registered 100F + higher than the other 3. What brand of EGT probes does Dynon use I'm thinking of replacing all 4 probes while I'm at it. I have emailed Dynon support but have not heard back from the company.
Aircraft Spruce has several offerings but I'm unsure of which ones would be compatable with my Dynon EMS-120.
Does anyone have an answer?

Thanks

Dave
RV-7
C=GCPD

Click to expand...

I replace a Dynon EGT probe every year or so. They're not a long lasting product, but are fairly cheap, if ordered from Aircraft Spruce. I just wait until I get a odd reading and put a new one in the next time I have the cowl off. Seems to be the cheapest solution.

-John

Okay, probably a dumb question here, but when replacing the Dynon EGT probe, does it disconnect somehow from the wire at the probe end, or do I need to disconnect from the EMS box and pull the entire wire+probe out?

The D-180 (presume D-120 as well - no idea about Skyview) have connectors ~5' from the probe. These plug into connectors you attach onto the harnesses that plug into the Dynon.

In short, follow the brown thermocouple lead from the probe, and you should find the connectors somewhere.

HTH?

I'll have to check it out next time I'm under the cowl...I don't remember brown thermocouples, but that just means I probably have a bad memory!

Shielded

Gash said:

I'll have to check it out next time I'm under the cowl...I don't remember brown thermocouples, but that just means I probably have a bad memory!

Click to expand...

The EGT (and CHT) probes on mine are shielded with bare wire mesh up to the point where the connect to the brown wires with the spade connectors. Probably about 4' - 5' from the probe. Mines a Skyview but I think the Dynon EGT/CHT probes are the same as the D series.

All of our EGT probes are the same for the D series and SkyView. They also use the same wiring harness, which has a quick disconnect under the cowl.

They are OEM'd for Dynon and not just bought from another vendor, so there isn't anywhere else to buy a Dynon one except from us or a Dynon dealer.

We did switch to a more robust and expensive design a few years ago, so you may find newer ones from us will last longer. They are a wear item though, as nothing survives in 1,500F exhaust forever. Thermocouples also age and drift off temperature in those environments.

If you don't want to use Dynon probes, thermocouples are standards, and any "K Type" thermocouple will work. Dynon supports grounded and ungrounded probes. Thicker, heavier probes will last longer but will also react slower.

FYI, I recently changed out my probes (GRT EIS but uses the same "K" type thermocouple). I did a some research into the various probes available (grounded vs ungrounded, Inconel vs Hastealloy) and their price points. Ended up buying the "long-life" ones from GRT at $52 each - they have a 5 year guarantee.

Thanks for the info guys. I noticed the last time I did some exhaust work and had to pull out a probe it was really difficult to get out due to the deposits on the thermocouple. I had to do lots of wiggling, twisting and pulling to finally get it out. There was nothing elegant about my technique! I was wondering if there's a better way to remove the thermocouple? Maybe use some mouse milk or similar stuff? Would love to hear some ideas.

DYNON EGT Probes

I have an answer thanks to Dynon Tech Support. The EGT probes Dynon uses are Type "K" available from Aircraft Spruce. Part number 10-01169. Just under $50 each. I'm ordering 4 to change them all.
Thanks for your responses and to Dynon for it support.
So now we all know

Dave
RV-7
C-GCPD

I have had good service from my original Dynon probes, now in use with my G3X. Over 1000 hrs., I run exclusively LOP and my probes show no signs of deterioration except for some deposits.