Ongoing oil pressure flakiness

[FlyingMonkey]

Even after I had the sender replaced, my oil pressure has still been intermittently giving me problems. Today after flushing the coolant from my engine and refilling, I ran the engine to check for leaks. It started at 70psi, then settled back to 45psi. As the engine warmed the pressure sank until it was reading about 28-30psi at 2100rpm. On run up to 4000rpm the pressure dropped to 20psi and stayed in that range for the 30 seconds or so I kept the revs up.

 

I have been suspecting the wire termination on the sender ring terminal, the wire has pulled away from the plastic stress relief and it feels a little loose. I went to pull the wire off to inspect it and the terminal would not unscrew, it just turned but didn't loosen. broken or stripped apparently.

 

So screw this, I ordered the Lockwood remote sender kit and the two post sender. Is there anything I need to know to tell the installer about it? Does the line need to be filled with oil first, or does the small amount of air in the system not hurt the engine? Where have you guys grounded the sender? Stuff like that.

[FastEddieB]

Andy,

 

I applaud both your inquisitiveness and your gumption.

 

But maybe another trip to Dahlonega may be in order?

[Anticept]

Even after I had the sender replaced, my oil pressure has still been intermittently giving me problems. Today after flushing the coolant from my engine and refilling, I ran the engine to check for leaks. It started at 70psi, then settled back to 45psi. As the engine warmed the pressure sank until it was reading about 28-30psi at 2100rpm. On run up to 4000rpm the pressure dropped to 20psi and stayed in that range for the 30 seconds or so I kept the revs up.

 

I have been suspecting the wire termination on the sender ring terminal, the wire has pulled away from the plastic stress relief and it feels a little loose. I went to pull the wire off to inspect it and the terminal would not unscrew, it just turned but didn't loosen. broken or stripped apparently.

 

So screw this, I ordered the Lockwood remote sender kit and the two post sender. Is there anything I need to know to tell the installer about it? Does the line need to be filled with oil first, or does the small amount of air in the system not hurt the engine? Where have you guys grounded the sender? Stuff like that.

 

Do NOT fill the line with oil. It works on air pressure, just like the fuel sender. The remote sender fitting has a tiny tiny orifice that goes on the engine, and take it to the firewall where the fuel sender is. If you get a longer bolt, you can even mount it to the same spot on the firewall.

[FlyingMonkey]

Might be Eddie. If putting a new ring terminal on the wire and relocating the sender does not solve the issue, I'll have to have a Rotax guy really investigate. But if that work does not solve the issue, I will have to conclude it is not safe to fly and find somebody to make a house call to Winder. I think Tim from Dahlonega will do that.

[FlyingMonkey]

 

 

Do NOT fill the line with oil. It works on air pressure, just like the fuel sender. The remote sender fitting has a tiny tiny orifice that goes on the engine, and take it to the firewall where the fuel sender is. If you get a longer bolt, you can even mount it to the same spot on the firewall.

 

Ha, I don't have a fuel sender (no FP gauge in my plane).

 

If the sender works on air pressure, why does oil come out of the fitting on the engine when the stock sender is removed? Is the remote sender unit a different type?

[Anticept]

Look at the sender. It too has the tiny orifice. It only needs a tiny bit of movement to actuate the sender.

[FastEddieB]

But if that work does not solve the issue, I will have to conclude it is not safe to fly and find somebody to make a house call to Winder. I think Tim from Dahlonega will do that.

 

Tim has a tool van and will travel.

[mocfly]

Andy,

Are you running with UMA gauges?

 

[Roger Lee]

The amount of air in the line isn't an issue. The air will move up and out of the hose as oil naturally fills it. It does have oil in it and if you want to fill it with oil it won't hurt a thing, but it is a small 1/4" hose. You can attach the ground wire from the sender to any grounded surface even the battery ground if you wanted, but there are other grounds available in the area.

[Anticept]

Huh. I swear my line is still filled with air. I need to check that!

[FlyingMonkey]

Thanks Roger. I won't have the installer fill the line if it's not a problem, I just didn't want to risk getting air in the valve train, as you have said often that can cause "Bad Things".

 

Interested in your opinion Roger, does this still look like a sender/wiring/gauge/ground issue to you, or something more involved like a tired oil pump?

[Roger Lee]

"look like a sender/wiring/gauge/ground issue"

 

 

 

Yes, I'm reasonably sure. It's either a sender, loose wire or poor ground. I highly doubt it's your gauge.

[FlyingMonkey]

Cool thanks, I'm trying to follow your mantra of "eliminate the easy stuff first".

[FlyingMonkey]

Andy,

Are you running with UMA gauges?

 

I don't know who makes them. They are the small factory gauges. I think my airplane was originally an all analog base model, with the D100 added at the Dealer (Airtime Aviation in Oklahoma) and the primary flight instruments retained as backups.

[Roger Lee]

The small gauges are UMA.

[Runtoeat]

Andy, my original engine mounted oil pressure sender was causing the same gage readings as yours. Now have 75 psi at start and constant 45 to 50 psi after warm up. You'll ask yourself why you didn't go with the remote mounted sender sooner.

[FlyingMonkey]

Andy, my original engine mounted oil pressure sender was causing the same gage readings as yours. Now have 75 psi at start and constant 45 to 50 psi after warm up. You'll ask yourself why you didn't go with the remote mounted sender sooner.

 

Thanks Dick, I sure hope that's the case, this thing has been a basket case on oil pressure since day one, it's on it's third sender, it was replaced right before it was delivered in June, and then once again since...the last one lasted about a month. I'm thinking the wire connection might be weak too, so that will all get beefed up at the same time.

[mocfly]

Andy,

I would make up a new db9 connector and run a single white wire to the pressure sensor signal post and run a new single wire from the db9 connector directly to the central grounding point located on the intake manifold.

If you have your schematics it will show the pin outs. It took about 2 hours when I installed mine, and I still made a video of the line routing from the pump back to the gauge just to make sure it was ok. I think the video is located in a post along with Roger's input.

Let me know if you doesn't have your prints and I will post the pin out that I got from UMA.

 

I was told by a pretty reliable source that much of the problems we have with the wiring is directly related to the amount of sales that FD had and it ramp up of the factory.

[cdarza]

I too still have same issues. Pressure will indicate all the way to yellow, if not red. I either shut down and restart (which usually gets the gauge back in the green) - or flip the ALT and BATT switches off - then on again. I have the remote mounted sender which i hope to install soon and rid me of this annoying little problem.

[Roger Lee]

Have you guys already installed the new style oil pressure pluge screw, spring and oil pressure regulator cone (mushroom). If not you should. Some of these may be caused by the old ball bearing and spring rubbing on the case housing. Cost is about $75 and it takes 15 minutes to install.

[Ed Cesnalis]

Have you guys already installed the new style oil pressure pluge screw, spring and oil pressure regulator cone (mushroom). If not you should. Some of these may be caused by the old ball bearing and spring rubbing on the case housing. Cost is about $75 and it takes 15 minutes to install.

 

We did that recently along with a dedicated ground. It fixed my issues.

[FlyingMonkey]

Have you guys already installed the new style oil pressure pluge screw, spring and oil pressure regulator cone (mushroom). If not you should. Some of these may be caused by the old ball bearing and spring rubbing on the case housing. Cost is about $75 and it takes 15 minutes to install.

 

Not even sure if I even know about this...how can we tell what we have installed?

[Ed Cesnalis]

My old style was a simple ball in a spring and had scoring on the spring. The upgrade was more complex.

[Roger Lee]

Andy,

 

Call me because this will need some additional info. You would need to do this mod to get the 2000 hr extended TBO provided your plane is newer than about June 2006. It will also help people with any of the 912's get better pressure regulation and many see additional pressure.

[FlyingMonkey]

Will do Roger.