What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Superior XP-360 with HIGH oil pressure

walkman

Well Known Member
I'm looking for ideas as to why the oil pressure on my engine is HIGH.

XP-360, about 500 hours. Runs perfectly, low oil consumption, all compression 78 or better (cold!). It does sling some oil out around the prop seal, possibly due to the high OP.

Its always been a little high on this engine, meaning 80-85 in cruise. I've noticed its recently crept up to 90 and occasionally bounces a little higher than that.

Just did the CI all filters and screens clear, no issues with oil temp or anything else.

The oil pressure relief valve is of the adjustable type and is cranked way the heck out.
 
Most VDO sensors start to fail by reading high. I would start by replacing the sensor. Very uncommon for oil pressure to rise beyond normal readings for any given viscosity/ temp.
 
I had and built a superior 0-360 in their shop. I had to adjust the oil pressure valve, I think it is on the top rear engine. As far as the leaky oil prop seal mine leaked at 70 hours and many others did as well, Superior didn't use the Lycoming type seal so have it replaced with the Lycoming prop seal 0-360 rubber seal no leaks in 250 hours. Mine also didn't use oil just put in 7-1/2 Quarts in and it was still there for each 50 hour change.

How to adjust a superior Vantage 0-360 oil pressure relief valve
Max engine oil pressure 95 min 55
This is on 72-50-00 of this maintenance manual from this guy:
http://rv7-a.com/manuals/Lycoming Maintenance Manual.pdf
 
I had a new Mattituck IO 360 that the log book showed to have been test run at factory but when I installed it oil pressure was set way too high. I had to back out the adjustment so far it concerned me enough to plumb in a manual gauge just to verify. Electronic gauge was correct all along. Do not know how it was run at factory set like it was.
 
Page 93 of 170 of that manual i sent says if you can't get it to adjust any lower Counter clockwise you may have to use a different spring table 72-50-00.1 shows the P/N SL68668(purple) for lower pressure. Hope that helps
 
Page 93 of 170 of that manual i sent says if you can't get it to adjust any lower Counter clockwise you may have to use a different spring table 72-50-00.1 shows the P/N SL68668(purple) for lower pressure. Hope that helps

His oil pressure has been stable for the last 500 hours. I think we should not be suggesting that the O/P attempt adjusting the relief valve until the indicated pressure has been confirmed to be accurate. Oil pressure drifting upward after 500 hours of service is a very uncommon scenario. On the flipside, VDO sensors routinely fail, well before TBO, with inaccurate, high readings.

Your guidance would apply to a new engine, but not necessarily to a recent pressure drift after years of stable performance and no parts replacement.

Larry
 
Last edited:
As I mentioned, the oil pressure adjustment is cranked out pretty much to the end of its travel. I have all the maintenance books and know how to adjust it.

Its still high.

The sensor might be an issue, I thought the failure mode was low pressure. I'll replace it, they're cheap enough.
 
His oil pressure has been stable for the last 500 hours. I think we should not be suggesting that the O/P attempt adjusting the relief valve until the indicated pressure has been confirmed to be accurate. Oil pressure drifting upward after 500 hours of service is a very uncommon scenario. On the flipside, VDO sensors routinely fail, well before TBO, with inaccurate, high readings.

Your guidance would apply to a new engine, but not necessarily to a recent pressure drift after years of stable performance and no parts replacement.

Larry

Its crept up about 10 or so PSI since it was new. Maybe 12 psi. I remember after I got done with my break in seeing 78, now its regularly hitting 90 and I've adjusted it out further.

I did solder on a separate case ground on the sensor which runs to the firewall to just make sure it was properly grounded. That stopped the rapid fluctuations due to electrical issues, but didn't change the overall number.
 
Oil pressure

First thing I would do is plumb a mechanical gauge into the same line as the sender. Ground run or fly it if possible and verify that the oil pressure indicating system is not giving you incorrect readings.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 
I had similar symptoms about a year ago. Talked to GRT where I had gotten my oil pressure sensor gauge; had to laugh when they suggested tapping on the sensor with a screwdriver. Laughed even harder when it worked!

Erich
 
I had a new Mattituck IO 360 that the log book showed to have been test run at factory but when I installed it oil pressure was set way too high. I had to back out the adjustment so far it concerned me enough to plumb in a manual gauge just to verify. Electronic gauge was correct all along. Do not know how it was run at factory set like it was.

Interesting, mine was built in 2006 and made some metal in the first filter. I have overhauled a few engines since then and none have ever looked quite like that. Another builder on the field had the exact same experience...
 
I had similar symptoms about a year ago. Talked to GRT where I had gotten my oil pressure sensor gauge; had to laugh when they suggested tapping on the sensor with a screwdriver. Laughed even harder when it worked!

Erich

Seriously? lol

Well, I think I can find a screwdriver :D

Thinking about that, I wonder it its something to do with air bubbles in the line.

Many years ago, well out to sea heading for some Bahamian island, I had an oil pressure gauge that started acting like a reverse altimeter. Since I was IFR following an NDB out to MYLS I was getting nervous. Landed safely, tied the airplane down, idled the engine and cracked the line. Apart from the oil bath I took it actually solved the problem.
 
Last edited:
Back
Top