Sudden high oil pressure - is this real?

[gossend]

Flying behind my IO-320 the other day, the Grand Rapids EIS alarmed for high oil pressure. The trip limit is set at 90 psi on my system, and when it tripped it indicated 90-92. Normally reads 75. The oil temp remained constant at 165. What would cause this?

 

[BJUST]

Had a similar issue on my RV-9A a while back. Problem was related to the oil pressure sender.

 

[Ironflight]

That is a common failure signature for the VDO sensor (the silver can type). I've had a couple of them fail "high" just like that, and they are easy to replace. If you take it apart, it is all mechanical, and easy to see why they go out. Definitely not built to take a ton of vibration.

I had two of them fail in fairly quickly on one airplane when they were mounted on the engine (it came that way - we didn't build it). After the second one, we remote mounted the third one, and it lived in blissful happiness ever after.

Of course, I also had one fail on a manifold mount, but that was after about 1500 hours.

 

[jjconstant]

Hi Dick!

Like Paul, I had some failures on the high side, but with both fuel and oil pressure. I replace the oil pressure transducer once already and I went through 3 fuel pressure transducers until I bit the bullet and went for the more expensive 3 wire transducer. It has worked flawlessly. All transducers are mounted on the firewall with the manifold that Van supplies. My oil pressure transducer has just started to fail high again

It's low oil pressure I'm more worried about, but I am less than comfortable learning to ignore the big red light so I just reset the alarm to a level that won't trigger on the high side. I wish GRT offered a 3 wire transducer for oil pressure too.

During the troubleshooting phase, I used a mechanical pressure gauge to verify that the sensors were failing and not the engine!

Out of curiosity, how's the 12?

 

[AndyRV7]

Can we talk about this in a little moe detail? For example, how do you replace one and where is it? I am using what I believe is a Vans pressure gauge.

I'm a new owner myself (RV-7) and have had some quirky oil pressure readings very similar to the OP. Mine normally cruises at 80 psi but every now and then, it jumps to around 90-92 psi for no apparent reason, AND while I am not looking. Then, later in the flight or the next flight, it will be back to "normal" at 80 psi. It was always virtually in the green so no real worry to me but it is the unexplainable differences that bother me. I began logging my pressure and some other data to see if I could see a pattern. Nothing is apparent.

Before I knew much about the plane, after I just purchased it, it seemed to be 60'ish at 1000 rpm on start-up, around 70'ish on the ground before takeoff but under a little more power, and 80'ish in flight. But I don't remember it ever being different. Now it seems to be more inconsistent, but in the green.

Thanks. Andy

 

[jjconstant]

Replacing it involves decowling the airplane and tracing a small flexible line, typically from the back of the number 3 cylinder and usually leading to an aluminum block or manifold on the firewall with several small can-like things on it with at least one electrical wire each coming out of each can, then going through the firewall to the engine instrument.

Unfortunately, the fuel pressure transducer and the oil pressure transducer frequently look identical and you have to look on the housing to see what pressures they are manufactured for. The fuel pressure transducer will be at the end of a line coming from the fuel pump.

Replacing them is easy. Buy the appropriate one, disconnect the electrical wire from the old one and then unscrew it from the manifold. Apply some white teflon paste to the threads if you like and screw the new one back into the manifold, reconnect the wire and test. These are pipe fittings so you screw it in rather tightly.

 

[AndyRV7]

Thanks. I am going to look for this!

 

[LifeofReiley]

Flying behind my IO-320 the other day, the Grand Rapids EIS alarmed for high oil pressure. The trip limit is set at 90 psi on my system, and when it tripped it indicated 90-92. Normally reads 75. The oil temp remained constant at 165. What would cause this?

Dick, what the heck are you flying with an IO-320 ? Hmm, a new toy?

 

[Yen]

I had this problem with Vans gauges. I found a loose connection at the gauge was the cause of the high pressure. Easy to fix, depending upon access to the ear of the gauge.