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erratic oil temp-

dreed

Well Known Member
Hey all-

I had an erratic oil temp/warning yesterday. This is the second time I've had this, and just looking for places to look/advice.

The first time was on a similar day temp wise, got the warning and throttle back and did a precautionary landing. I checked oil levels, looked for anything obvious, etc. and nothing seemed off. Took off, everything was back to normal and flew for another 1.5 or so with no issues/oil temp warning and everything seemed back to normal. I've had several flights since with no issues/warnings.

Yesterday, It was only mid/low 50's yesterday- I was in level flight after a gentle climb to 2500-3K feet when I started getting an alarm to check oil temp

Still low time on the aircraft/engine (IO-390), but the jumps in temp seem pretty unachievable to me.

I checked grounds, and am now thinking sending unit or could this be the vernatherm?

Thanks in advance- Short vid attached

https://youtu.be/SjxqhKvTBKw
 
Connection Issue

To me, it looks like a connection issue. You didn't say what system your engine monitor is, but usually these are resistance based senders, and therefore depends on a solid ground connection, on the sender itself and the engine monitor hardware.

The vernatherm is just a thermostat, so I doubt it could respond as fast as your video shows, it would either fail to open or fail to close, and you would see the temp drift into high or low territory and stay there.

You might want to check out my other post on the topic of senders if your system has a similar sender, you should be able to test the resistance across it and verify sane values.

After that, I know you said you checked grounds, but I would check again, and check the voltage side also: A nominal voltage is passed across the sender, which is a variable resistor, so a smaller nominal voltage is returned to the monitor. This difference is then correlated to a temp value, and yours jumping around like that, I would start along those lines rather than engine hardware.

While you were climbing, did you notice it jumping around like that? In other words, as you climb or even when first taxiing around, is the temp jumping erratically by +15-20degs, but since it's still cool, it's not jumping up into the warning territory, so you just didn't notice it since it doesn't trigger the alarm?
 
Thank you very much-

Sender/wiring was my initial thought as well given the speed of the jumps as well as the randomness on flights. I'll head to the hangar later and check all the grounds and connections again. If no progress, may toss another sender in it to verify.

I am running Advanced 5600's with their ACM for EMS.

Dan
 
That's electrical in nature - not physically possible for the oil to change temperature that quickly, nor for the probe to react to it that quickly.
 
I have been dealing with the same issue and mine is for sure a connection or prob issue as it has done it also on the ground. It is a Garmin probe which has two wires and not relying on the engine case for ground. It also can not be connected directly to the ground as it will read a different temp that is not accurate. After tying multiple type connection, I end up replacing it since it was still under warranty but I don't have enough hours on it yet to say it is fixed.

The temp could go from 140 to 250 in a matter of seconds and come back to lower temp again in a matter of seconds.
 
Apologies for a bit of thread drift...

I have a GRT EIS 6000, and am also having a bit of an issue with the oil temp, although presumably on the opposite end of the range. Twice in the last couple of months, my oil temp has been "stuck" on 59 degrees, which I think is the lowest readable value. After taxi to the run up area and perhaps 3-4 additional minutes it jumped to 90-ish, essentially instantaneously. For the remainder of the flights all has been normal--oil temp rock stable at 180 degrees +/-.

It's not "real", e.g. cold Wx. I'm in southern Arizona and ambient temps have probably been 70 or so at start. Obvious choices are a failing probe or a loose connection. I pinged GRT tech support yesterday, both to ask whether this is a typical early failure mode and to confirm the p/n for a replacement, but thought I'd check with others on VAF wrt their thoughts and experiences.

For now, my plan is to order a sensor and have it on the shelf, ready to install if needed when I troubleshoot (while the cowl is removed for the upcoming oil change). In the interim, if the problem doesn't self-clear by the run-up, it would be an abort.
 
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