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  #1  
Old 07-04-2019, 07:02 AM
Mark Dickens's Avatar
Mark Dickens Mark Dickens is offline
 
Join Date: Apr 2012
Location: Collierville, TN (KFYE)
Posts: 1,475
Default Zero Oil Pressure

Oil pressure (as measured on my Dynon Skyview) went to zero last evening on the ground while testing the installation of my new CS prop. I had done a couple of run ups, exercised the prop, etc and then got a warning from Skyview. I taxied the 200 yards back to the hangar while watching the oil temps and CHTs. By the time I got there, the indicated pressure was zero and I shut down quickly. Oil temps and CHTs were all about what they were before the warning (121F for oil, mid 300s for CHT), so in looking for corroborating information that I really had an oil pressure problem, I wasn't able to find it.

No oil loss, no oil leaks, dry as a bone FWF. I did do an oil change very recently and had 7 qts in the engine. I send oil samples to Blackstone at every change and I had a great report from them on this change. The engine has about 200 hours on it, a Titan IOX-370.

So, need a plan to figure out what's happening. One obvious possibility is a bad oil pressure sensor (it's the Kavlico sold by Dynon). So, plumbing in a mechanical gauge makes sense and then I'd remove the top plugs and run the starter with ignition off to see if I get a pressure indication. Another idea is to remove the oil pressure line and fitting to check for obstruction. If none of these point to the answer, what's next (other than a teardown)? Ideas?
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  #2  
Old 07-04-2019, 08:20 AM
TS Flightlines TS Flightlines is offline
 
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Location: Ridgeland, SC
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Default

Mark---DEFINIATELY plumb in a remote oil pressure guage and check the pressure. Not sure what else has been done as far as making any changes that 'might ' have created an electrical issue. Rare to have real oil pressure just go away like that.
Let us know!!

Tom
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  #3  
Old 07-04-2019, 09:21 AM
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Default

I am a firm believer in a mechanical and electronic oil pressure gauges. Easy to install mechanical one.
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  #4  
Old 07-04-2019, 09:23 AM
sf3543 sf3543 is offline
 
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Location: San Antonio, TX
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Default

You might also consider checking the crankshaft plug, since you said you have a new CS prop, to make sure it is properly installed. Especially if you changed from a fixed pitch prop.
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  #5  
Old 07-04-2019, 09:57 AM
Mark Dickens's Avatar
Mark Dickens Mark Dickens is offline
 
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Location: Collierville, TN (KFYE)
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Quote:
Originally Posted by sf3543 View Post
You might also consider checking the crankshaft plug, since you said you have a new CS prop, to make sure it is properly installed. Especially if you changed from a fixed pitch prop.
Fortunately, Titan installed a rear plug with the threaded boss for a pipe plug, so all I had to do was install that. Pardon the probably dumb question but if the pipe plug came uninstalled somehow, how would that affect the engine oil pressure? Wouldn't it just drain back into the crankcase?
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https://www.marksrv8.com
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  #6  
Old 07-05-2019, 04:22 PM
Mark Dickens's Avatar
Mark Dickens Mark Dickens is offline
 
Join Date: Apr 2012
Location: Collierville, TN (KFYE)
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I still haven't solved the mystery, but the plot thickens. I bought a Harbor Freight mechanical oil pressure gauge and it showed 0 PSI as well, so that seems to exonerate the Kavlico oil pressure sensor. I drained the sump and removed the oil screen and it was normal (few specks of carbon). Because of the low engine time and historical reliability of these oil pumps, I was skeptical that the pump was the problem and decided to start the engine and watch the oil temps and CHTs to see if anything untoward popped up, and after two separate starts, running up to as much as 2300 RPM, everything was good. CHTs were normal and the oil cooler was hot when I shut down, so oil was being pumped. Still the sensor reported 0 PSI.

Now here's where it gets interesting. First, I can't exercise the prop any longer and second, the oil temps basically got to ambient and sat there with no rise.

My hypothesis is that the pipe plug I installed in the rear crank plug has come out and this is why the prop is not responding to the governor. But would this also affect the 0 PSI reading on the oil pressure sensor and the flat oil temp?

I've been pouring over Lycoming's docs this afternoon, but have come up empty. Any input from the real engine gurus?
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RV-8 #81077 Super Slow Build
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First Flight 11/20/2016
https://www.marksrv8.com
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  #7  
Old 07-05-2019, 05:49 PM
kkmarshall kkmarshall is offline
 
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Location: Central Tx
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Man,I don't think I would be brave enough to run the engine with 0 pressure on a mechanical gauge! YMMV
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  #8  
Old 07-05-2019, 07:40 PM
mahlon_r mahlon_r is offline
 
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Posts: 1,060
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wow!! zero op on a mechanical guage and 2300 rpm? Twice? My advice is disconnect the oil cooler line from the center of the accessory housing. That port goes directly into the oil pump output. Crank the engine with the spark plugs out and see if you even had flow. If not, don't worry about the problem you will find it during the complete teardown. Dangerous troubleshooting plan you had....
Good Luck,
Mahlon
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  #9  
Old 07-06-2019, 07:21 AM
oaklandaviator oaklandaviator is offline
 
Join Date: Dec 2014
Location: Somerville, Tn and Little Rock, Ar
Posts: 143
Default Undo what you did

I once had a mechanic who was helping me get my A&P say if the engine quits after gear retraction what should you do? Answer, undo what you did and put the gear back down. Incidentally this was just down the road from you at the old Arlington airport that is now gone.

You installed a new propellor that is in the oil system. First thing to do is remove the prop and governor. Something isn't right in that system most likely. And definitely don't run the engine with no oil pressure. That's an expensive troubleshooting technique!

Tommy
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  #10  
Old 07-06-2019, 09:16 AM
ALagonia ALagonia is offline
 
Join Date: Jul 2017
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Quote:
Originally Posted by oaklandaviator View Post
I once had a mechanic who was helping me get my A&P say if the engine quits after gear retraction what should you do? Answer, undo what you did and put the gear back down. Incidentally this was just down the road from you at the old Arlington airport that is now gone.

You installed a new propellor that is in the oil system. First thing to do is remove the prop and governor. Something isn't right in that system most likely. And definitely don't run the engine with no oil pressure. That's an expensive troubleshooting technique!

Tommy
The old Arlington airport was real handy for those of us based at Charles Baker, 2M8. When the weather was low we would shoot the approach at Arlington and then perform what we called the Loosahatchie transition. Following the Loosahatchie river would put us on a right base for rwy 36 at 2M8. My first engine overhauler, John Jewell, was located at Arlington. He moved to Holly Springs when they shut the airport down.
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