Erroneous oil pressure and temperature indications

[edemalleray]

:-[ We installed the D 180 with the sensor package on my Glasair fitted with a Lycoming. We decided to keep the old steam gauges for the oil pressure and temperature since they are no go items. Therefore the D 180 and the gauges are using the same sensors. And surprisingly, the steam gauges are still working well, indicating the good values, while the D180 indicates weird values :-/. Anybody has an idea of why and how we could fix it ? the idea is to keep the steam gauges as back ups in case of D180 failure. If impossible, never mind.
hank you for your help

 

[DBRV10]

Re: Erroneous oil pressure and temperature indicat

Most likely a difference in ground levels. in other words a difference of potential between the Zero Volts around your airframe.

Check very carefully to have good clean and strong earth connections and all items 0v references tied to the one earth bus.

I have a new install D180 and from the first power up all the temp and pressure items read true and realistic numbers so far (engine not started yet tho...) but static tests all seem fine. Grounding is usually the issue. Even if you think they are good, they probably are not.

Hope this helps.

DB

 

[dynonsupport]

Re: Erroneous oil pressure and temperature indicat

You cannot share senders in a system. The gauge (steam or the D180) powers the sender, and so if you hook up two systems, they both power the sender and end up messing everything up because they assume a specific power source.

In your case, the gauge is probably 12V while the D180 is 5V, so the gauge appears to work because it's overpowering the D180. Technically, the gauge is off slightly as well anytime the D180 is connected, but it might be a small error.

On top of all of this, even if it did work, it's not redundancy at all, since you have only one sender (which is just as likely to fail), and the failure of the gauge can take out the other gauge.

 

[edemalleray]

Re: Erroneous oil pressure and temperature indicat

Thank you for your quick answer and your help . I was suspecting something like that :-[. But that means if the D180 fails, then I lose many infos, something I have not thought deep enough before making my choice. It is probably not the most effective one :-?.