Low oil pressure in my 290D2

[cgfyl]

Soooo, I've had enough of this ongoing issue and want to finally resolve it. I've had numerous issues with the plane since I had it out of restoration. All have been solved with the exception of this one. I have the oil at about 5 litres and when I take off she is in the green about 65psi. After a while i watch the oil pressure gradually drop to between 56 - 58psi and it stays there. I just flew the Rockies about 4 hours and this is what happened. I land with between 4.5 - 5litres of oil. I checked the oil pressure gauge today with air and it reads about 15-18psi high. This has me worried because of the oil pressure being in the yellow on long stretches. I do oil changes after 25 hours and nothing is found in the filter. I have a spin on oil filter as well. Ive also had an issue with lower oil temps, the only way to keep the temps up is to cover the oil cooler with tape and foam.

Any suggestions would be greatly appreciated. I'd hate to tear the engine apart; however, if i have to I will. I don't want to sell or swap a dud engine as I'm in the market for a 0 320.

[Pacer 24C]

Use 50 wt oil with STP until you get an 0320

[richardb]

Interesting that you put 5 liters of oil in the sump I have the same engine and I run 6 quarts of aeroshell 100 plus 50 weight. If I'm not mistaking you can adjust the bypass to increase or decrease oil pressure.

[cgfyl]

I have the old style pressure relief valve with a new stiffer spring and washers, same results. I'm using Phillips 20x50 oil. I'll try going to 6 litres and see the results. In the past if I had anymore than 4.5litres it would just be thrown out of the crank case vent. I've now installed a crank case vent oil breather, it seems to be working well.

[richardb]

Interesting sounds like there might be some restrictions somewhere in the oil lines. I'd pull that bottom plug out of the pan and check that screen around the sump pump line. Also have you tried using Marvel Mystery Oil I usually add 1 ounce for every quart of oil every time I do an oil change keep things cleaned out. Correct me if I'm wrong but isn't liters less then quarts.

[Pacer 24C]

More oil will likely not help unless you have a very oil temp problem - I wonder if you have the current oil pump required by the 1996 AD.

[cgfyl]

I'll be taking the oil lines off and blowing them out for sure. I haven't taken the oil drain out in a while as I have the quick drain. That will also come out and a real good inspection will take place. I spoke wit some friends this past week who swear by MM oil, in both oil and fuel. I use cam guard in my oil. 1 litre = 0.946353 quarts. so basically 1 for 1.

The oil pump AD was complied with when the engine was overhauled just over 100 hours ago. My oil temps tent to stay around 140 or less, unless its very warm outside. I have no verntherm as one will not fit in the spacer between the accessory case and spin on oil filter.

[Don D]

Up to 9 washers under spring. Check oil cooler system for restrictions. Check with temporary gauge. Go back to engine overhauler to check for internal problem. Might have installed wring bearings. Ouch! New overhaul to me means oil pressure 75# with 3 washers hot or cold.

[bushcruiser]

Have found 2 items effecting oil press after new oil pump installed. 1 oil hole drilled per s.i. 1341, drilled at wrong angle causing pressure leak below the end of the idler gear shaft. 2. New pump housing has small oil hole in machined face that the o-290 accessory case will not cover up. Both cause low oil press at normal temps. Bob

[Pacer 24C]

Agree the SI 1341 drill is not easy to do correctly and I believe it is best not to do the mod - It can be welded up if drilled - as you know the oil pressure can escape in the back of the cavity and come back thru the hollow shaft and lose pressure.