Low oil pressure when hot

[caymancraig]

My turbo Aerovee has run perfect on the ground from the very first start. Got oil pressure before first start by turning over engine with starter for a few seconds. Always starts right up and has what seems a high oil pressure of 90-100. Works down as soon as the engine warms up to about 45-60. During my first and second flight everything was fine until I was up for about 10 minutes on each flight. At that time the oil pressure goes to 15-20. First flight EGT was high so I had throttled back to 2900 for a fast climb of 100mph. Second flight CHT and EGT was both high and I throttled back the same. I know I have work to do on the carb tuning and the cowling. My concern is the low oil pressure. Both times I reduced power and return to the airport right away as I was still in the pattern. Both times no oil leaks, and correct level of oil. Both times engine started right up the next morning and the ground run was normal. I'm putting on a mechanical oil pressure gauge tomorrow to verify that the Dynon sensor is not getting hot and giving bad readings. Is there something I could have done wrong with the two plungers?

Thanks all, Craig Mock

[Rynoth]

What is the oil temp when the pressure drops that low?

Is there something I could have done wrong with the two plungers?

Well, yes, the plungers are each different and the spring lengths are different, so might be worth verifying they are correct (grooved plunger/long spring in the slot nearest the prop hub.) Also wouldn't hurt to make sure they're moving freely (spring pressure enough to close them against low oil pressure.)

I assume you're running the Aerovee manual-recommended oil?

[caymancraig]

Yes, recommended oil.

[MichaelFarley56]

Craig,

First, congratulations on your first flights on the Waiex! I'm glad to hear there is another "turbo" up and flying! Do you have any pictures to share of your Waiex?

As for the oil pressure, the first recommendation is to do just what you stated; add a mechanical pressure gauge to to verify what pressure you're actually getting. Speaking for myself I know I've had marginal luck with digital gauges so you may not have an issue at all.

It's normal for oil pressure to drop as the oil heats up and thins out, so if it turns out that you really are getting low oil pressure you'll probably need to look over the pressure regulator plunger and also take a look at the tolerances on your oil pump cover plate. If there's a gap between the cover plate and the gears that could lead to pressure loss.

Let us know!