My oil pressure has gone from 38-40 psi in cruise to 78-80 psi??? 100 on take off. O-520. I'm having trouble down loading my JPI data to see when this happened, if it was sudden or more gradual. The factory gauge is also showing high pressure, I'm not sure if the JPI 830 has a separate sender or uses the factory sender. I know the temp gauge has a separate sender. I have cut open the filter to check for metal, nothing. A bit weird??

JamieG wrote:My oil pressure has gone from 38-40 psi in cruise to 78-80 psi??? 100 on take off. O-520. I'm having trouble down loading my JPI data to see when this happened, if it was sudden or more gradual. The factory gauge is also showing high pressure, I'm not sure if the JPI 830 has a separate sender or uses the factory sender. I know the temp gauge has a separate sender. I have cut open the filter to check for metal, nothing. A bit weird??

That's a grounding indication. Get it to a good mechanic (or get a good mechanic to it) before you run it again.

And, no offense intended, but you need an engine monitor to tell you when your oil pressure doubled?

MTV

Just to add to what's been said....not much can go wrong in that system that's "good." Not knowing the history of that engine, i'd pull the pressure adjustment housing and see if you have a stuck sliding valve.

Bill

fiftynineSC wrote:Just to add to what's been said....not much can go wrong in that system that's "good." Not knowing the history of that engine, i'd pull the pressure adjustment housing and see if you have a stuck sliding valve.

Bill

+1 on the above. A little bit of grit or galling or a burr on the slider could easily cause this.

I have a Continental (smaller O-300) engine, and I was incredibly surprised to learn just how sensitive the relief valve mechanism is. You "adjust" the oil pressure on the engine by adding or removing washers from under a spring, which keeps the piston/plunger (the sliding valve) pressed against a valve seat. My O-300 was running 10-15% above the minimum, so I thought I'd add a washer or two in there to bring it up just a little.

Two additional washers resulted in a startup pressure spike (80-100 PSI), so I immediately shut down, removed one washer, and tried again. This time it only went to 70-90 PSI, so I shut it down again and replaced the one extra washer with a thin washer. The thin washer still spiked the pressure, so I had to go back where I had started, with the same number of washers as it had, and the same 10-15% over minimum that I had.

In my case (pretty warm weather, oil pressure a little low), I solved my problem with a little help from Andy Granatelli

EZFlap wrote:

fiftynineSC wrote:Just to add to what's been said....not much can go wrong in that system that's "good." Not knowing the history of that engine, i'd pull the pressure adjustment housing and see if you have a stuck sliding valve.

Bill

+1 on the above. A little bit of grit or galling or a burr on the slider could easily cause this.

I have a Continental (smaller O-300) engine, and I was incredibly surprised to learn just how sensitive the relief valve mechanism is. You "adjust" the oil pressure on the engine by adding or removing washers from under a spring, which keeps the piston/plunger (the sliding valve) pressed against a valve seat. My O-300 was running 10-15% above the minimum, so I thought I'd add a washer or two in there to bring it up just a little.

Two additional washers resulted in a startup pressure spike (80-100 PSI), so I immediately shut down, removed one washer, and tried again. This time it only went to 70-90 PSI, so I shut it down again and replaced the one extra washer with a thin washer. The thin washer still spiked the pressure, so I had to go back where I had started, with the same number of washers as it had, and the same 10-15% over minimum that I had.

In my case (pretty warm weather, oil pressure a little low), I solved my problem with a little help from Andy Granatelli

Not so sure that STP is an authorized aviation oil additive, but it did wonders for my old 53 Ford flathead when I was a kid. I changed oil every 1000 miles (common back then), and until I used STP, I would add 2-3 quarts between changes (some argued that with that much oil burning, I didn't need to change the oil at all!). One little can of STP, though, and the oil burning slowed to the extent that at 1000 miles, it would be down maybe a pint at most. Good stuff--but again, not so sure it's authorized in aviation engines.

Cary

Cary wrote:Good stuff--but again, not so sure it's authorized in aviation engines.

Cary

Huh? What? S-T-... what??? All I did was go to the local spiritualist, and we had a seance so I could contact Andy, and see if he could give me some fashion advice.

If you think that I'd ever use some un-approved Pep Boys Wally World stuff like that in my oil, you just better repent and Marvel in the Mystery of my pure unadulterated aviation gasoline !

Well, I never... !

mtv wrote:

JamieG wrote:My oil pressure has gone from 38-40 psi in cruise to 78-80 psi??? 100 on take off. O-520. I'm having trouble down loading my JPI data to see when this happened, if it was sudden or more gradual. The factory gauge is also showing high pressure, I'm not sure if the JPI 830 has a separate sender or uses the factory sender. I know the temp gauge has a separate sender. I have cut open the filter to check for metal, nothing. A bit weird??

That's a grounding indication. Get it to a good mechanic (or get a good mechanic to it) before you run it again.

And, no offense intended, but you need an engine monitor to tell you when your oil pressure doubled?

MTV

I am grounded at my mechanics. I have a JPI 830 but can't seem to download my data to see when it happened and how sudden. We backed off the relief valve almost completely and ran it briefly. Still reading high (35 psi at idle). Put another gauge in the line to check the gauges aren't faulty. Reading was the same as the factory gauge in the panel. The JPI monitor T's off the line that goes to the factory gauge. Pulled the relief valve and checked it out. It seemed to be working fine with no obvious debris or restriction of movement. Pulled the secondary one as well (yes there are two) which is not adjustable. We had drained the oil as it was due for a change and meant less leakage when pulling the valves. Changed and cut open the filter, no metal. Put the valves back in and re filled with oil from his shop which was Shell 100W Plus, not the Phillips XC 20W-50 that we normally use. Did one start then shut down to make an adjustment. Went to start second time and the starter adapter just slipped. Wouldn't turn one compression. That shell 100 plus is slippery stuff. It seemed to work fine with the Phillips but I guess its on the way out and the shell "plus"oil which has some kind of anti wear additive showed that up. Pulling the starter adapter for recondition tomorrow.

Sounds like you are doing what needs done, If you determine that the gauges and senders/sensors, if used, are OK and the pressure relief is OK then you need to look further. the oil pump creates flow, pressure is a factor of resistance to flow, things that can cause resistance to flow could be anything like a foreign object stuck in an oil passage or a blockage of an oil passage. You may have had a it of gasket travel into the oil gallery and plug off flow to the camshaft or possibly a bearing has spun on the crankshaft and blocked the flow.
Lots of guesses but you will just have to keep digging to find it.
Please let us know what shows up.
Good luck.

No joy in resolving this issue. Pulling the engine to look further.

Sorry to hear the bad news. Hopefully it's an easy fix!!


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