Oil Pressure Problem

Jimboscr · #1 02-07-2016, 07:41 AM

Hi everyone. I am looking for the collective wisdom of the group to help with a HIGH oil pressure problem I have been having. First the facts. I have an IO-360 fuel injected Lycoming in my RV8 that has a total time of 44 hrs. It has been running fine, within the pressure parameters although it has been on the higher side of normal (85 - 90 Psi). However now I have been experiencing very high pressures (120 Psi) whenever the throttle is pushed forward, mainly on take off. I should also mention I am in Australia where it is definitely Summer at the moment and the ambient air temperature is hovering anywhere from 80F - 110F.

So far I have done the following: (according to the Lycoming trouble shooting lists)
1/ Checked the pressure relief valve, the ball bearing is smooth and shiny and there is no evidence of sticking (it is only 44 hrs old)
2/ checked that the pressure relief channel is clear by using the Lycoming suggested copper wire. It is clear.
3/ I am using the correct grade of oil.
4/ However when I looked at the oil temp I found that it was quite cool. When I sat on the ground and ran the engine for about 15-20 min the oil finally got up to the correct temp and the pressure problem seemed to go away.

So my question is: Does this mean that my Vernatherm is stuck in the open position, thus constantly directing the oil to the oil cooler and not allowing it to warm up enough and its this higher viscosity oil that is causing the oil pressure to be to high?

I am going to pull it and do a temp check on its operation, but I would like the Engine Gurus to give me their opinions, and comment on wether my reasoning is correct or not.

Thanks in advance. Cheers

Jim

RV3bpilot · #2 02-07-2016, 08:01 AM

check the pressure using another gauge... I found my sender to be at fault...Good luck...

Jimboscr · #3 02-07-2016, 08:03 AM

Oops I forgot to mention I have a Dynon system and I did use a manual gauge to check if it was working and it was within 3 Psi, so the gauge is reading accurately.

lr172 · #4 02-07-2016, 11:26 AM

I would do a full throttle take-off once the engine if fully warmed up. If you are back to 80-90, then the cold oil is the cause. In that case, I would reduce my hot OP down to 70-75 (keeping cold pressures in spec). If not, you should seek professional advise. OP should not randomly increase by 30% without some other variable changing. It can't be the oil cooler, as the pressure is measured downstream of cooler. A restricted cooler would show as reduced pressure, if anything.

You may not have a stuck vernatherm. Does your oil eventually rise to and stabilize at 180-190? If so, it may be working. Do you notice that it takes longer to get to 180? If so, there may be another reason for this, such as a blockage that is pushing more oil past the cooler, as it is in a bypass mode below 180. The best indication of a failed vernatherm is temps moving a lot based on engine RPM (excluding cold weather ops) or stabilizing somewhere other than 180-190. This is much easier to observe in warm ambient temps. Don't evaluate in climbs, as once you over run the set point of the vernatherm (185) oil temp fluctuations no longer point to vernatherm failure

It is open when cold and closes when hot. It is very easy to pull the vernatherm and test it in hot oil or hot water. At 200, it should be fully extended and there is a spec on the minimum travel from contracted to expanded, but I don't remember it off hand (may be .160"). It's easily found on the web. I have disassembled one or two and was able to make them operational. They collect sludge and carbon in tight fitted parts that make them stick.

Garrysimports · #5 02-08-2016, 04:01 AM

you may have too many washers behind your oil relief spring. this causes the relief spring to have to much pressure on it, so it takes more pressure to move the ball off the seat.

Jimboscr · #6 02-08-2016, 04:23 AM

I don't think its the pressure relief valve because there was no problem for the 1st 40 hrs and I have tried adjusting it. It made a little change to the overall pressures but nothing like the amount needed. Also that doesn't answer why the oil takes so long to heat up, and the fact that the pressure problem improves as the oil gets warmer. I attempted to get the vernatherm out to test it but I don't have the correct size tool. It is bigger than the 1" socket I have so does anyone know the correct size?

Thanks for the help and suggestions so far It is helping me run through and organize my thoughts on what might be happening.

Jim

Pat Stewart · #7 02-08-2016, 06:03 AM

Sounds like the Vernatherm. At your temps the engine should come up to temp pretty quick. On the pressure valve you said you checked the condition of the ball, if you did not check the condition of the seat you should take it back out and check it. I have had one engine that had a bad seat on a very new engine and I had to use the Lycoming tool to cut a new seat.

Jimboscr · #8 02-08-2016, 07:16 AM

O.k. thanks for that Pat. I didn't check the seat, so I will go and have another look, that at least is easy to get at. Unlike the Vernatherm!

Jim

Kent Ashton · #9 02-08-2016, 07:28 AM

That oil pressure relief system is stone-simple: high pressure moves the ball, relieves the pressure. I have had a ball jam open from a bit of oil container ring, resulting in low oil pressure; I suppose it could jam closed or be adjusted-closed to cause high pressure but I'm betting on a gauge problem.
-Kent

a25afm · #10 02-08-2016, 11:38 AM

Just went through this same problem. Everything checked out good on the ground. Replaced gauge and sender with no fix. Ran a new ground wire to the gauge and problem was corrected. Solid 80 psi.