O-200 oil pressure

[benbell4140]

Hello. I have an experimental o-200 with 40 hours since major. All yellow tagged parts. The engine was last run in late 2019. When I installed it and did my first start up (earlier this year) it had zero oil pressure. I shut it down about 15-20 seconds later and primed the oil pump thru the fitting on the oil filter adapter. I got oil pressure on the next start up but it seems to be on the low side. It was 32 psi at idle with oil temp at 60 degrees. Pressure didn’t change much with rpm or temperature. (I’ve only gotten the oil temp up to 110 degrees). I checked the relief valve and it appears to be clean and in good shape. While I had it off I added 3 washers. This brought the pressure up to 38 psi but again it doesn’t change much with rpm or temp up to 110 degrees. I’ll attach some pics of the oil screen which shows some type of fiber looking material, it’s almost like fine hairs from a shop towel. Do you think it’s possible that I have some trash in the restricted “jet” that is in my oil pressure sending hose? I also confirmed the oil pressure with a mechanical gauge as well. Reads exactly the same as my dynon.

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[Bell206]

I have an experimental o-200 with 40 hours since major. All yellow tagged parts.

So who did the "major" and per what reference? The screen looks more like dirt/debris than a shop towel.

 

[benbell4140]

The overhaul was done by the previous owner of the engine. Logs show new ECI Titan cylinders. New factory continental crank. Case and accessory case overhauled and yellow tagged by DivCo. Yellow tagged mags and carb. New sky tech starter. New b and C alternator. New slick mags. All gears yellow tagged. By the book it appears to be all new or tagged components in the entire build. I’m sure I’m missing some components (logs are not with me at the moment) I just expected higher oil pressure than what I’m seeing. I know that continental says 10psi is ok at idle but I would assume that would more common on a high time engine.


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[Magman]

Not sure what you are expecting for oil pressure.

I believe the normal range is 30 to 40 psi at flight rpms.

You can bleed the line by loosening the connection at the Gage while running.

If you run your finger through the screen cavity you may pick up more stuff.

If you drain oil through a paint strainer you may find still more of it.

Flushing with solvent may help clean up.

Was screen ever pulled after assembly?

 

[benbell4140]

This is the first time the screen has been pulled since the overhaul.


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[Gary Ward]

This is the first time the screen has been pulled since the overhaul.


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It does not look good to me, lot's debris on the strainer.
Seems like it should have been checked before 40 hours?

Has the plane flown for 40 hrs now?
If so I would fly it some more and re check that strainer in another 5 or so hrs.
Might need to clean more of the oiling system like the pressure relief again?

I keep any kind of cloth shop towels away from any engine that I overhaul or rebuild especially red shop towels.

Good luck with it.

 

[benbell4140]

It does not look good to me, lot's debris on the strainer.
Seems like it should have been checked before 40 hours?

Has the plane flown for 40 hrs now?
If so I would fly it some more and re check that strainer in another 5 or so hrs.
Might need to clean more of the oiling system like the pressure relief again?

I keep any kind of cloth shop towels away from any engine that I overhaul or rebuild especially red shop towels.

Good luck with it.

Thanks. I didn’t build the engine. I just took a chance on a used low time engine with a recent overhaul. Logs look perfect and the price was fair so it was worth a chance. My airplane is still under construction and will be flying in the next year. I just finished wiring up the dynon panel and this is the oil pressure that I’m seeing. I’ve spoke to serval other o-200 flyers and they seem to think my pressure is on the low side which has me concerned.


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[Bell206]

This is the first time the screen has been pulled since the overhaul.

In 40 hrs? Do you know if any engine break-in guide was used in this 40 hrs? Mineral oil?

Do you think it’s possible that I have some trash in the restricted “jet” that is in my oil pressure sending hose?

The "jet" you refer to is merely an orifice to prevent excessive oil loss should your oil line leak. Usually they clog and show no pressure vs reduce the pressure reading.

I just expected higher oil pressure than what I’m seeing.

Small Continental engines are known to be oil pressure challenged. While there should be a higher reading cold in most models, the press tends to reduce at normal operating temps to lower readings (20-35psi). Now if your engne wasn't broke-in properly the low oil pressure could be due to some other issues related to the break in vs normal variations.

FYI: eventhough the engine is installed in an E/AB does mean it is always best to ignore all the OEM recommendations. Engine break in being one of them.

 

[Gary Ward]

Thanks. I didn’t build the engine. I just took a chance on a used low time engine with a recent overhaul. Logs look perfect and the price was fair so it was worth a chance. My airplane is still under construction and will be flying in the next year. I just finished wiring up the dynon panel and this is the oil pressure that I’m seeing. I’ve spoke to serval other o-200 flyers and they seem to think my pressure is on the low side which has me concerned.


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Might want to install a temp mechanical oil pressure gauge for a second reference gauge.

 

[benbell4140]

In 40 hrs? Do you know if any engine break-in guide was used in this 40 hrs? Mineral oil?

The "jet" you refer to is merely an orifice to prevent excessive oil loss should your oil line leak. Usually they clog and show no pressure vs reduce the pressure reading.

Small Continental engines are known to be oil pressure challenged. While there should be a higher reading cold in most models, the press tends to reduce at normal operating temps to lower readings (20-35psi). Now if your engne wasn't broke-in properly the low oil pressure could be due to some other issues related to the break in vs normal variations.

FYI: eventhough the engine is installed in an E/AB does mean it is always best to ignore all the OEM recommendations. Engine break in being one of them.

Thanks for your input. I can only go by what the engine builder told me, I’ll have to look in the books to see which oil was used.


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[benbell4140]

Might want to install a temp mechanical oil pressure gauge for a second reference gauge.

Gary. Thanks for your input. I did hook up a mechanical gauge last weekend and it shows the exact same as my dynon.


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[Dan Thomas]

The oil pressure looks fine. What is not fine is the lack of oil pressure after startup. The small Continentals are famous for that. The oil pump is built into the accessory case, and has an aluminum cover over the pump gears, and that cover is a metal-to-metal fit. No sealant, no gasket, no nothing, and trying to add anything there results in problems. The plate must be a flat as possible, not warped from previous tightening of the nuts (made worse by sealants), or that oil will leak out over time after shutdown and you'll have no oil pressure. The rod bearings get beat up and the crank journals suffer.

The filter crap looks like dust that was in the crankcase during assembly. Parts like that sit around and dust settles on them. An overhaul shop has to be clean like a hospital, and the assembler has to be constantly watching for any contaminants. And that screen should have been off to check for metal right after the initial ground run, then again after five hours or so. Best is to install a spin-on filter adapter and get the oil properly clean; those screens just stop the big chunks.

 

[benbell4140]

Dan thanks for the information. This engine was sent to me without any oil in it and had been sitting for around 8 months.(not sure if he drained the oil just prior to delivering the engine or not) I fogged everything once I received it with a fogging oil. It does have the spin on oil filter already. I cut the original filter that I removed from it and didn’t see anything unusual. However, I didn’t do an oil analysis. I left a part out also. I originally had an MGL efis and was showing 60psi cold and it would drop to 45 or so once warmed up. But apparently those numbers were incorrect. I just recently installed the dynon and this is when the pressure was lower. But I have since tested with a mechanical gauge that reads exactly what the dynon is showing. So I’m assuming the MGL system wasn’t reading correctly. Funny thing is the pressure only changes 1-2 psi with cold oil verses 110 degree oil at idle. And the psi doesn’t change much more than that with increased RPM’s either.


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[Magman]

Since the O-200 does not have to have the oil drained to check the screen it is

my practice to check prior to first flight. As others have said 40 hrs is WAY to long.

First screen pull looks ugly a you see the edges of gaskets in there.

The engine could have lost prime when it was off and may have been upside down.

It does sound like you are doing a lot of ground running though?

 

[benbell4140]

Since the O-200 does not have to have the oil drained to check the screen it is

my practice to check prior to first flight. As others have said 40 hrs is WAY to long.

First screen pull looks ugly a you see the edges of gaskets in there.

The engine could have lost prime when it was off and may have been upside down.

It does sound like you are doing a lot of ground running though?

I’m just assuming the screen hasn’t been off prior to my ownership due to the amount of crap on the screen. I could be wrong. The engine sure was upside down when I received it. I’m am doing some ground running but I haven’t ran it up to cruise rpm yet. Just to around 1,600 RPM. It runs amazing and has 79 over 80 in all of the cylinders. I’m just unsure about the oil pressure. Maybe I’m over thinking it but I honestly did think it should have around 55psi at idle when cold. Hopefully I didn’t hurt any bearings when we started with no oil pressure. Just ran it at idle for 15-20 seconds waiting for pressure to build. Then we primed the pump and it hasn’t lost prime since then.

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[Magman]

My recall is 5 psi idle , 30-40 psi flight

You werewayoff with expectations.

The TCM o/h manual with give what you need to know.

A Cessna 150 AFM will provide similar.

Draining oil through a strainer and flushing sump with solvent ( DO NOT RUN)

will likely clear things up and confirm status.

Quite frankly; I’m more concerned about your ground running time and

procedures.

It’s amazing to me how many folks see “ in the green” but no idea of numbers.

 

[Dan Thomas]

From the overhaul manual:



http://veteranflyg.se/wordpress/wp-...75-C85-C90-O-200-Overhaul-Manual-Aug-2011.pdf

 

[benbell4140]

Just a quick update. (I know it’s been a while) new accessory case on the way due to tore up oil cavity.

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[Dan Thomas]

Just a quick update. (I know it’s been a while) new accessory case on the way due to tore up oil cavity.

That's a huge score. No wonder the pressure was bad. That overhaul must have been pretty careless, with all that fuzz on the screen and that big score that must have been cut by a pretty big chunk of metal.

 

[odie451]

Just a quick update. (I know it’s been a while) new accessory case on the way due to tore up oil cavity.

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Is this something that could have been caught by DivCo, when they were overhauling the case?

 

[Magman]

“ Key-Start” 0-200’s have a bearing that accommodates the Shaft from the Clutch.

I‘ve seen the needle bearings migrate and be found in the Pressure Screen.

The path would be through the Standpipe and Oil Pump first.

IIRC the cavity looks similar to this one.