IO 360 oil pressure problem

[Barry G]

Can anybody shed any light on an oil pressure problem I have with the IO 360 in my RV-8 ?
After initial start the pressure climbs within a few seconds to 50 psi - and it stays there !
Warming the engine to 90F and choosing any rpm from minimum (650rpm) to about 2200 rpm makes no difference to the pressure.
We've fitted a known correct dial gauge directly to the engine to eliminate gauging problems.
We've changed the spin-on filter, pulled the oil screen and cleaned it, thoroughly rinsed out the Raven inverted oil valve, reservoir and all the hoses.
We've had the relief valve in and out several times and it looks fine.

By backing the relief valve off we can reduce the pressure to around 35 psi and by screwing it right in we can get 60 psi. But, once selected the pressure remains constant at all revs.

We're finding it difficult to get the oil temp. any higher as the OAT is only about 4C and we have the cowls off to enable the dial gauge to be seen from inside the aircraft.

Anyone any ideas ? Barry G

[jrs14855]

You really need to provide a lot more history. History of the engine, if new was it run in a test cell. Was the inverted oil system recently installed, ie has the airplane been flown without the inverted system. With the Christen system on parallel valve 360, my recollection is that in cold weather the oil pressure on takeoff would be bottom of the green, the oil pressure would rise to mid/ high green as the oil temperature increased. In other words the opposite of what normally occurs without the inverted oil system.
One option would be to disconnect and cap the oil cooler lines at the engine and repeat your tests.

[Barry G]

Sorry 'JRS', should have given more info. The engine has done 300 faultless hours till now, the Raven inverted oil system was fitted at 65 hours and the aircraft has flown fine with it for about 3 years.
Up until this fault the oil pressure on start up ran up to around 60 psi then gradually reached the mid 70's at 70-80F where it then stayed until shut down. There was some minor variation in the pressure with the revs but only a few psi.
From the runs we have done we're pretty sure that oil isn't flowing through the cooler. We've only been achieving 90F max. because of the ambient temps etc. but the cooler remains stone cold throughout.
Thanks for your input. Barry G

[az_gila]

Bad Vernatherm valve?

[maniago]

Originally Posted by Barry G

Can anybody shed any light on an oil pressure problem I have with the IO 360 in my RV-8 ?
After initial start the pressure climbs within a few seconds to 50 psi - and it stays there !
Warming the engine to 90F and choosing any rpm from minimum (650rpm) to about 2200 rpm makes no difference to the pressure.
We've fitted a known correct dial gauge directly to the engine to eliminate gauging problems.
We've changed the spin-on filter, pulled the oil screen and cleaned it, thoroughly rinsed out the Raven inverted oil valve, reservoir and all the hoses.
We've had the relief valve in and out several times and it looks fine.

By backing the relief valve off we can reduce the pressure to around 35 psi and by screwing it right in we can get 60 psi. But, once selected the pressure remains constant at all revs.

We're finding it difficult to get the oil temp. any higher as the OAT is only about 4C and we have the cowls off to enable the dial gauge to be seen from inside the aircraft.

Anyone any ideas ? Barry G

Well you need more sleuthing. Make a simple list of all the causes you can think of and work off the easy stuff first. What were the engine & oil temps when you first started noticing this? If the oil is not temping up, then vernatherm is clearly part of your sleuthing. What grade of oil are you using? Oil could be so thick its activating the filter bypass as well. When did you last change it? (oh right, I see that now sorry)

Absolute worst case, you've got a gross internal leak- spun bearing, transfer collar out of whack etc, but don't jump to those conclusions. Do the simple and cheap analyses first. Have you ever run the motor in cold like this before?

Youre never gonna get it up to operating temps on the ground in this weather. Fly it or park it.

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Ok better idea. Join the Lycoming section of Yahoo groups and post there. Your issue is not specific to RVs so you might get a larger cross section of "experts"....