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Question about oil pressure and when it bypasses

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2 months 1 week ago #22173 by Bill Hertzel
Replied by Bill Hertzel on topic Question about oil pressure and when it bypasses

amhst56@gmail.com wrote: Bill,
I was thinking to try to install the mechanical pressure gauge in the hole in front of the sender hole. I think it's for a turbo? ...


The port on the face of the Oil Pump is a Pressurized Oil Supply Port commonly used to supply Oil to a Turbo or a Prop Governor.

FYI, while this port appears on the Oil Pump it is actually far removed from it functionally.
The Oil leaves the Pump on the Left side of the engine near the Oil Filter.
It travels down the Left Crankcase Half to the rear of the engine then crosses over to the Right Crankcase Half and then flows forward to where it appears on the Right side of the Oil Pump.
Functionally, this Oil travels about three feet getting from the Oil Pump To the Oil Sender.
Whatever pressure you see on the sender, you can be assured that all parts of the engine are seeing the same or slightly better pressure.

What is strange is that your pressure varies slowly over the course of 5 to 10 seconds.
Most people with Oil pressure variations normally see it flutter rapidly more times in one second than you can count. This video is an example of the typical problem



If it turns out to be an Oil Pressure Regulator problem, I have a proprietary fix for that.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
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2 months 1 week ago #22175 by garrett
And like Bill said I think you could temporarily replace the gauge as a test to rule it out.

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2 months 1 week ago #22176 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
Thx Bill and Garrett,

Since the turbo hole isnt the best, I was thinking to T it right at the sender and add a mechanical guage and see if they are same or different.

I know of one splice on ether white wire from the guage I was going to jumper out also

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2 months 1 week ago #22183 by garrett
UMA Technical Support

UMA offers technical support on all its instruments free of charge. Here's how to contact our support department:
Mail: UMA, Inc.
P.O. Box 100
Dayton, VA 22821
Email:
(Aircraft Support) techsupport@umainstruments.com (Shefik M.)






Phone:
*When calling, please specify whether
you are needing medical or aircraft support. Local: 1 (540) 879-2040
Toll Free: 1 (800) 842-5578

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2 months 1 week ago #22184 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
Emailed then about 5am this morning and they got back to me pretty quick.
My resistance from engine to black wire was same as probe to probe so I don't think it's a ground


"Hi! You can test the gauge with variable resistor 0-200 ohms, connecting red wire to power+, black to GND and resistor between white and blk wire. Turn on the power (12Vor 24V) and changing resistance from 0-200 ohms you should see the pointer go from 0-130psi. But, I think you may have a bad GND connection through the chassis from the sender to the gauge black wire. This is very common problem with VDO kit (sender & gauge) just because bad GND. You have it connected, but somewhere between this two it may be loose somewhere. Additional wire connected to the gauge black wire and the body of the sender in most cases solving the problem.

Have a good day!

Sincerely,
Shefik "

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2 months 1 week ago #22185 by garrett
Yeah jumper the white wire between gauge and sender and make sure you have a good 12 volt DC connection. Also if you think you need to, get another resistive gauge with the same scaling (like a VDO) to compare. You can always return it.

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2 months 1 week ago #22226 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
I only had an HR before work, so instead of teeing the mechanical guage in, I decided to jumper everything out.
the white wire to sender
The black to ground bus
The ground bus to frame
Frame to negative
Negative to sender
Sender back to black wire

Great news! It worked!!
Bad news, im not sure which one did it.
I tightened all connection previously.
This time I will redo the white wire, disconnect all ground wires and clean all connections

photos.app.goo.gl/thtLT22dZCfCfEZv6

Thx all!!!

I am alittle confused how I got the same resistance from the guage black wire to the sender if one of the grounds are curroded...unless it was the white wire to sender splice?

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2 months 1 week ago - 2 months 1 week ago #22230 by garrett
Thats good news! Just remove one wire at time until the problem reappears. Vibration can contribute to bad connections intermittently. I had a red cube flow meter intermittent problem once and the wire was broken under the insulator at the connector
Last edit: 2 months 1 week ago by garrett. Reason: add text

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2 months 1 week ago #22248 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
Hi all,

Few quick questions about this topic.

How do I log the remote sender into my engine log?

If my poil pressure is good, should I still do the new mushroom pressure relief?

Does the new relief change the pressure of is it just a better, longer lasting design?

Thanks

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2 months 6 days ago #22252 by garrett
I would simply say (remote mounted new replacement oil pressure sending unit to firewall using kit provided by Lockwood aviation) including the fire sleeve. Keep the receipt for the kit and sleeve with the aircraft records.
If the oil pressure is not jumping around (you can find discussion on this forum) also see Bills video on top of page, you are probably OK. I would however research your engine serial number and log book to see if it needs the the new style plug and spring which extends the TBO from 1500hrs to 2000hrs. And if you upgrade you might as well change the ball to the mushroom, it works better.

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2 months 5 days ago #22268 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
Uuuggghhh!

I cleaned everything, flew and could not get oil pressure right again.

I put all jumpers back on and was going to take one off at a time, but oil pressure was not good.

It did get better with each takeoff though.

I'm now thinking it has something to do with tempreture?
First take off was around 28
Second was 35, then 40, then 50psi.

Guess I'll wait until tomorrow and take another flight.
Does oil temp have to be up to around 180 before takeoff?

Thanks!

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2 months 5 days ago #22269 by Bill Hertzel
Replied by Bill Hertzel on topic Question about oil pressure and when it bypasses
I would take a step back and complete the simultaneous dual (Electrical and Mechanical) gauging exercise.
The mechanical gauges respond instantaneously to any pressure changes.
Electronic gauges tend to display the pressure averaged over the previous few seconds.
- - - - -
The Oil needs to be at 50°C (120°F) before applying full power.
This will ensure that the Oil Pressure remains below 70psi which is the real concern.
Pressure tends to go DOWN as the Oil thins out when the temperature goes UP.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
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2 months 5 hours ago #22350 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
Sorry I haven't updated lately, been working alot of overtime lately...

I agreed with Bill and did his idea of hooking up both gauges. Sorry the video isn't better.
photos.app.goo.gl/RnaH72CuP7QMJxVA6

Did 6 takeoffs. The video shows first and last.
Could not get either guage to drop below 45?!?!

Got 8.7 ohms on the old sender and new 2 prong sender (Uma said it was good)
Replaced the guage with my ohm meter and did 3 takeoffs. I crossed referenced those readings with list that Uma gave me. From that test, seems like guage is good.

Any suggestions on what to do next?
I still have both guages hooked up, fly some more with them?
Put everything back to normal and fly with it dropping now and then in takeoff?

Bill,
I read an older post of yours, I believe it said that resonance of the motor sometimes make the oil pressure or sender jump around, think this is what it could be?

Thank all!

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2 months 4 hours ago - 2 months 2 hours ago #22351 by Bill Hertzel
Replied by Bill Hertzel on topic Question about oil pressure and when it bypasses
I will assume the FIRST Takeoff is the Second Video that starts with the Oil Pressure in the 60psi range and the Oil is cold.

It could be the regulator bouncing around but we can't tell until it goes wacky again.
The Key point to note will be if both gauges drift at the same time, or just one of them does.
If they both track together, then it is a regulation problem, if only one drifts, it is an instrumentation issue.

Right now it looks like it is working and "You can't fix it if it "Ain't" Broke!!!"

You do not need to keep videoing it every minute, just keep an eye on it.

P.S. I hope you are not trying to fly and video at the same time.

Bill.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
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Last edit: 2 months 2 hours ago by Bill Hertzel.

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1 month 4 weeks ago #22352 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
Thx Bill,

Actually the higher reading is from the last takeoff.

Guess I'll leave the mechanical guage on for a few more flights and watch it as u suggested.

Just seems wierd that adding a "T" and another guage solved the problem...
I do have the sender secured to the motor ground temporarily.
Maybe the sender is seeing less vibration than when it was on the firewall or motor?

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1 month 4 weeks ago - 1 month 4 weeks ago #22353 by Bill Hertzel
Replied by Bill Hertzel on topic Question about oil pressure and when it bypasses
Your Pressure changes are smooth but "Wonky"!!! :blink:
I would not suspect it is the regulator just yet.

The symptoms are more consistent with the Oil Pump Inlet hose being restricted.
The oil Pump is capable of moving 3 liters of Oil per 1000rpm.
In reality, it moves 2-3 gallons per minute at 5000rpm.
This is the equivalent of a typical Garden hose except it has to move that much Oil by Suction, NOT Pressure.
Any restriction in the Suction line is going to cause a partial Oil Starvation event at the OIl pump resulting in partial Oil Pressure.

I would disassemble and confirm that the Oil Path is unrestricted from the pickup tube in the bottom of the Oil Tank through to the Oil Pump.
Take it apart and run a Rifle Bore Cleaning Patch through it if you have to.
Get Anal!!! :ohmy:
Assume it is bad until you have confirmed that it is good.
Something is wrong here and pretending that it isn't will not end well.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
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Last edit: 1 month 4 weeks ago by Bill Hertzel.

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1 month 4 weeks ago #22354 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
Thx Bill,

Can u explain what u mean wonky?

I have the "T" at the remote sender.
There is a few ft of hose, could that be making it wonky?

Seeing 45 psi on all takeoffs, I thought we were onto something good?

Thx again

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1 month 4 weeks ago #22356 by Bill Hertzel
Replied by Bill Hertzel on topic Question about oil pressure and when it bypasses
Wonky
adjective Informal
1. crooked; off-center; askew.
2. (of a thing) unsteady; shaky.
3. not functioning correctly; faulty. <---<<< THIS!

The remote sender is not a factor in the Pressure Regulation.
The 45psi, more or less, IS Good! But...
Your Oil Pressure Goes UP instead on Down as it gets hotter.
Your Oil Pressure Goes DOWN Instead of Up with Higher engine speed.
This is just "Wonky"!!! :P

- - - -
Plus it is just a funny Word that doesn't get used enough.
I like to try to throw in uncommon words just to break up the day.
The smiles were added to indicate that I was just being facetious.
Be happy I didn't say it looked "Kattywampus"! ;)

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
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1 month 4 weeks ago #22357 by amhst56@gmail.com
Replied by amhst56@gmail.com on topic Question about oil pressure and when it bypasses
Ok...I like wonky...

Doesn't the 60 psi dropping to 45 when power is applied signify the by bypass opening?

Or should the bypass keep the psi steady?
Example: if spring opens by pass at 60 psi it will hold 60 and not drop?

If it's the second, then I am understanding why u think it maybe an inlet problem.

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1 month 4 weeks ago #22358 by Bill Hertzel
Replied by Bill Hertzel on topic Question about oil pressure and when it bypasses
The regulator starts to open at about 20psi and is fully open by about 35-40.
Any variation that is not attributed to the valve is due to the Oil Viscosity, Temperature and flow rates through the regulator.
Or... Something Else!
As such it would be expected that the Oil pressure would be highest when cold and running fast.
And lowest when Hot and Slow.
If the regulator existed in a perfect world, the pressure would stay at 40psi no matter what happened.
Most people see it drop to ≈30psi at a Hot idle and climb to 45-55 at 5500rpm.

The pressure dropping with Increased RPM (Flow Rate) is what is not normal.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
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The following user(s) said Thank You: amhst56@gmail.com

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