Zenith Aircraft Builders and Flyers
Online Community of Zenith Builders and Flyers
Solid-State Oil Pressure Sensor
It seems that the VDO resistor-type oil pressure sensors commonly installed on the Jab 3300 routinely wear out every couple of hundred hours - or less! I'm at 550+ hrs and noticed my 3rd VDO sensor was starting to show signs of failing - usually evidenced by sudden spikes of high pressure.
Some have tried to avoid this problem by either mounting the sensor on the lower oil gallery port (which gives lower oil pressure readings and has to be taken into account) or remotely mounting it via an oil line with the theory the oil line will absorb some of the oil pump's pulsations and extend the life of the sensor. I tried the lower oil gallery mount and saw no difference in the sensor's life.
It occurred to me to try one of the newer, solid-state oil pressure sensors. Aircraft Spruce sells a "Swift" 0.5-4.5v/100 psi sensor that they say is "similar to the Falcon" and "with no moving parts ... which does not allow the sender to become worn out mechanically." It costs no more (maybe even a little less!) than a VDO sender.
Since it is supposedly resistant to wear, I installed it in the original location that Jabiru uses and plugged the lower galley port. I display my pressure on the MGL XTreme EMS with the RDAC XF interface, so on the RDAC, I connected the red power wire to the +5v, the black ground wire to ground, and the signal wire to the OIL P connector. Someone had told me I would need to install a resistor in the signal wire, so I connected a 1/4w, 1 KOhm in series to the signal wire. I set the XTreme menu to "0-5v" sensor and chose the "UMA TIEU100" since both are 0-5v, 100 psi sensors. (NOTE: read further down in the discussion ... the Swift sensor is NOT a 0-5v sender, it's 0.5-4.5 volts and that makes a difference in the output!)
Initially, the sensor did not work correctly! I double-checked and found the pull-up resistor dip switch was "ON" on the RDAC, so I switched it off and it worked great after that. Hmmm - makes me wonder if that in-line resistor was really necessary and could I have deleted it and just left the pull-up resistor switch "ON" on the RDAC board? I suspect that's the case but since it is working fine, I just left it as-is.
I had also been advised I might need a capacitor to filter the signal and prevent erratic or jumpy readings. Again, however, it did not seem to be necessary and the oil pressure readings are quite stable. The person advising this had used a cheap Ebay Chinese sender, making me suspicious that's why he had to modify the installation - perhaps the "Swift" sender is a little better design/quality?
Anyway, now I just need to put a couple hundred more hours on the STOL 750 and see if durability is there! ;>)
John
N750A
Replies to This Discussion
-
Permalink Reply by Michel Royer on
-
Hi John.
went to hangar this AM and my 0 psi value is at 397 ADC.
So knowing that value and that you mentionned that it was pretty linear
I appllied the rule of 3 and put my 90 psi at 3573 ADC.
It should be pretty close but will monitor on my next startup.
Thx again
-
-
Permalink Reply by George Snedeker on
-
i am very new to the jabiru engine but today my oil pressure needle spiked to the top and wouldn't go down unless I turn off the master...is that indicative of a bad sensor? or a faulty gauge ....
-
Permalink Reply by John Austin on
-
Sounds like a failed sensor - it typically erratically spikes or stays at full scale deflection.
BTW, the solid state sensor continues to work great!
John
-
-
thanks John...I may order the sensor you mentioned and try it....as for installation for dummies like me can I hook the same power lead to the gauge that currently exists? another words plug and play or do I need to fun some different configuration
-
-
I can only speak to interfacing it with a MGL RDAC, which I detailed in the first post. But, the old sensor only had one wire - the solid state has 3: +5v, signal, and ground, so no, I'm sure it is not plug 'n play!
John
-
-
thanks john
-
Permalink Reply by Joe Hopwood on
-
Hi John,
I just noticed the solid state sensor is 1/8 NPT and the hole is 10mm. Did you use an adapter?
-
-
Pete Krotje who was at Jabiru USA told me the oil gallery port was actually tapped to 1/8 npt but the factory uses a VDO sender with a M10 x 1K thread. There are adapters available, but the threads are virtually identical. I've used Permatex high temp sealant and have never had a hint of leakage with senders of either thread. I really don't think an adapter is necessary, especially since the factory doesn't think so, either.
John
-
-
Think Pete is correct. The VDO does have M10 x 1K threads and a copper washer. However, when I put new one on it got pretty tight before it ever got to the shoulder and washer indicating the hole was getting narrower the further in it was screwed. I ran engine a while and got no leaks. Guess I will watch carefully for leaks and unusual oil consumption. The original was installed on engine when I bought it and I had not removed until today. However, I took it out by hand after about an eighth of a turn with wrench. I am sure I am tighter than that so not worried about too little torque.
Next to figure out how to interface the solid state sender with Skyview. Guess I will ask if anyone has done that.
Thanks again John!
-
-
It's a tapered thread so you just tighten it until it's good and snug, just as you would any pipe fitting. I had the same experience - it tightens up well before the threads bottom-out, so the provided copper washer is not necessary - and as I mentioned, I used Permatex high temp sealant, too.
John
- ‹ Previous
- 1
- 2
- Next ›
New from Zenith:
Classified listing for buying or selling your Zenith building or flying related stuff...
Custom Instrument Panels
for your Zenith:
Custom instrument panels are now available directly from Zenith Aircraft Company exclusively for Zenith builders and owners. Pre-cut panel, Dynon and Garmin avionics, and more.
Zenith Homecoming Tee:
Flying On Your Own Wings:
A Complete Guide to Understanding Light Airplane Design, by Chris Heintz
Builder & Pilot Supplies:
Pro Builder Assistance:
Transition training:
Aircraft Spruce & Specialty for all your building and pilot supplies!
How to videos from HomebuiltHELP.com
Developed specifically for Zenith builders (by a builder) these videos on DVD are a great help in building your own kit plane by providing practical hands-on construction information. Visit HomebuiltHelp.com for the latest DVD titles.
© 2024 Created by Zenith.Aero.
Powered by
