Oil temp/pressure

Hey Chris, I know this is a four year old thread, but I don’t see any final results. What was the solution?

Our gauge has shown about 27 psi for a couple of years. We switched from 20/50 to Shell 100 but it made no difference. Because it not deteriorated in the least over the past few years, we are betting on the gauge being off. I’ll be replacing it this week. We also have a new pressure relief spring on hand, just in case.

I have an oil analysis done with each change (every 20 hours) as well as the filter inspected.
No metal detected. Hopefully, it’s just the gauge.

Well crap. Now I can’t find the reference that says Continental recommends the W120 over 78 deg F ambient that I mentioned. In fact, the only place I can see it is in Shell’s generic data that they publish on their website. I wonder if that’s what I was looking at and mistakenly remembered it as Continental’s info. The C85 overhaul manual just specifies W40 in ambient temps over 40 deg F. Sorry.

I’m happy that the W60 puts me back in the green but wonder if it’s not a bit of a Bandaide and there is still a problem in the bearings, pump, or elsewhere. All this fuss over a few psi of oil pressure,

Chris

After a lot of experimentation I decided to try the oil specified in the C85 maintenance manual. As it turns out, it says that W60 oil should be used with ambient temps greater than 78 deg. So I switched out the oil (again) with Aeroshell W120. Here's the result:



The gauge is new by the way and I haven't gotten the color coded arcs on it yet. I replaced it to make sure the problem wasn't gauge accuracy. In any case, the pressure at cruise rpm, 180 deg oil temp, is now well within the 30-35 psi green range as specified by the maintenance manual. Straight W50 ran about 28 psi at 180 deg. Also, oil analysis, done on oil that was 25 hours old before it got hot here in SD and oil pressure became an issue, was stable and ok with just a tad too much copper.

I'm gonna say this is safe for summer flying now with close monitoring. When Fall comes, I'll probably be able to switch back to 20W50 weight oil. We'll see.

Chris

We had a similar problem with our 415C. The oil pump was and did bite the dirt. Don't fool around with it; get the oil pump checked.

Thanks Pat. I might just give you a call. But first I'm gonna try following up on what I found today.

After pulling the pressure relief spring I found things as shown in the pic and whereas the spring being broken into 3 pieces couldn't have helped, there was still some compressed tension in it. My theory is that it had to be shortened a little as a result though and this would have been made worse as the wire heated up causing it to lose even more tension and allowing the piston to fall away from the bypass channel prematurely. I ordered a new one from Aircraft Specialties today along with the copper washer for the dome nut that closes off the entire affair and will report back once it's installed.

Chris

Chris – I’ve unfortunately got some recent experience with this topic with my Ercoupe’s C-85, and what you’ve shared has plenty of similarities to my situation. My story is a very long one that I should write up some time, but in the mean time if you’re interested I’d be happy to talk with you about my low oil pressure journey. You can find my phone number in the EOC membership list (“List Members” in the “User Menu”).

Pat Webb
415-C
SN #450