IO-360 with intermittant oil pressure reading

[dhartz]

Hi all, I've been having intermittent oil pressure drop outs, more specifically, the pressure either reads fine in the green, or zero on the G1000.

This has happened while flying and sometimes never gets off zero upon startup. Happens when it is hot, or cold.

My mechanic swapped the oil and fuel pressure sensors, but due to the intermittent behavior, I haven't been able to get enough time in for a dropout to occur on either the oil or fuel pressure. We also cleaned the connector and the sensor-side pins with contact cleaner.

My suspicion is that this is more an electrical problem, related to the Amphenol connector. A few times when this is stuck on zero (while on the ground!) I can reach in and tap on the sensor, which is easy to reach through the oil door. This SEEMS to fix it, and I wonder if it is more a wiring or connector-related issue.

It seems a bit of a chore to replace that Amphenol connector and my mechanic didn't seem excited about it, at least not until we put more hours on. I suspect it might have to go to an avionics shop to get done right.

Anyone seen anything similar? Those Amphenol connectors are "military grade" and I would hope would work better than this, unless we having a wiring or cold solder joint.

Thanks.

keywords: oil pressure, sensor, sender, transducer

[Steve]

Those connectors are quite reliable. I would suspect an installation issue like a bad crimp or broken wire over the connector being bad.

[jwx96]

A number of years ago I used to rent a G1000 DA40. On one long flight home I got low fuel pressure readings, but not to zero, and the readings were relatively steady. I heard that the mechanic swapped the sensor with another one and found that the sensor was bad. It was replaced and the cost was not cheap. That doesn't sound like what's going on here. I agree with Steve that it sounds like a bad crimp or broken wire, and It sounds like you've localized the problem to within 1 inch in terms of the location. I would get it fixed. After all, it's a single engine airplane and it's the oil pressure reading. A functioning oil pressure gauge is required for daytime VFR flight - A TOMATO(oil pressure gauge) FLAMES. Sometimes mechanics require a little encouragement from pilots and owners.

[Diamond_Dan]

You might find this thread helpful. I believe the sensor is the same as used for fuel.
viewtopic.php?t=3671

[steve_falconer]

You might find this thread helpful. I believe the sensor is the same as used for fuel.
viewtopic.php?t=3671

Is this the case only for G1000 or also VM1000 equipped?

[Steve]

VM-1000 equipped aircraft have different sensors for fuel pressure and oil pressure. They look the same, but have different pressure ranges.

[Charles]

I have a VM-1000 and had a similar issue where pressure would suddenly fluctuate wildly in flight. The connector was fine but one of the wires had broken off about 5mm from the connector and was kept in place by the other conductor, causing an intermittent connection.

[dhartz]

I have a VM-1000 and had a similar issue where pressure would suddenly fluctuate wildly in flight. The connector was fine but one of the wires had broken off about 5mm from the connector and was kept in place by the other conductor, causing an intermittent connection.

Thanks Charles, I'll look for that!

[jwx96]

The other difference between the G1000 sensors and the VM1000 sensors is that the VM1000 sensors/transducers are less expensive. They’re available through Diamond and supplied to Diamond by JPI.

[Bing]

I had the same problem and the solution was to replace the hose that connects to the transducer. Over time the inner portion of the hose had become weak and would collapse on itself thereby blocking the passage. Since it was replaced, the problem has not reoccurred.