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fact checking the oil pressure gauge

Tim-NJ

Active Member
All,

I saw the answer to this in a thread that I can no longer find. I have some erratic-ness in my oil pressure gauge and bought a manual gauge from HF to do some testing.

My oil pressure sending unit is mounted inside the firewall under the panel, I originally thought of unscrewing it and putting the manual gauge there for ground testing but then I don't get to compare the two so we'll scratch that bad idea.

Is there a preferred location on the accessory case or block that I should be using? I see a plug very close to the pressure relief valve that looks like a good candidate but thought I'd ask the collective before I do something I'll regret later.

Thx!

Tim
 
Unscrew the sensor and install a Tee fitting there, plug both into the Tee fitting. That gives you comparison with the existing sender at the point of pressure detection.
 
Different locations

Is there a preferred location on the accessory case or block that I should be using? I see a plug very close to the pressure relief valve that looks like a good candidate but thought I'd ask the collective before I do something I'll regret later.

Different ports will show different pressures.
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Tim---you might rethink having the sender in the cabin. In the unlikely event that the sender starts leaking, it would spray hot oil on any passengers in the cabin, including the one flying the plane. Happens in automotive applications, so it CAN happen in experimental aircraft.

Tom
 
I didn't think of tee'ing it off. Excellent suggestion, I'll definitely do that.

Tom - I'm the buyer but great point nonetheless. Now I'm compelled to admit that the fuel pressure sending unit is an inch over from the oil pressure sender. They are both on the pilot side so it's me who will be sprayed with oil and then catch fire. Alright... I probably shouldn't kid around like that. Since I'm the buyer I can't do the annual and will certainly seek the advice of my A&P and local EAA chapter in a couple months when it's due.

Tim
 
Tim,
You can?t do the condition inspection (unless you have an A&P), but you can modify your homebilt as much as you want, as long as you feel comfortable doing this kind of work. Moving your sensors to the front side of the firewall (out of the passenger area) shouldn?t be that hard to do. If it?s your first time doing something like this, ask a mechanic friend or your local EAA chapter Tech Counselor to check your work. If you make a major change (this isn?t a major change), you?ll need to contact your local FSDO and enter a phase 1 test detail, but that?s no big deal either. You won?t have to do that by just moving your oil and fuel lines to a safer location.
 
Thank you all for the suggestions.

  • Changed the oil and took a sample for the lab
  • Changed the filter (nothing of concern inside)
  • Cleaned the oil screen (a very small amount of what looked like red paint chips - I have a red painted Mattuck)
  • Removed, cleaned and inspected oil pressure relief valve (nothing found)
  • New crush washers on the oil screen and relief valve.
  • Did a ground run, no leaks so I safety wired the applicable parts and closed up my RV.

I was at 45 hours since last oil change.

After all that my oil pressure is now where it had always been with no bouncing around. Go figure... I have a new problem but will start a new thread.
 
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