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Oil Pressure and Question for the Experts (Mahlon!)

fl-mike

Well Known Member
Oil Pressure and Question for the Experts - Resolved

New Titan IOX-370 on an RV-8, Titan cold air sump, Hartzell constant speed prop, large 20006A oil cooler on showplanes mount, piston squirters.

Breaking it in on Philips M 20w50XC. Right at ten hours now. I started with six quarts, and added a quart when it was down a half quart or so. I drained it today, and got exactly four quarts out of the sump. So, I'm assuming that the cooler and filter are holding a bit.

Not happy with the oil pressure (since first flight and full oil). It doesn't seem to be regulating well, and is lower than I'm used to. I've turned in the bypass ball spring screw a bunch, checked the ball valve seat, replaced the ball and spring. No change. Checked the screen, all good. It is within Lycoming "good" range, but my old engine was pretty rock solid at 80 until low RPM. I'm flirting with "too high" at cold takeoff power, and then it drops off as it heats up to 60psi or so.

The old plane (Mattituck TMX-0360) never saw below 64 PSI and typically mid 70's at short final , mid to high 80's in cruise. Low 90's on climb out.

I notice that when I pull some G, the pressure comes up about 20 psi (to 80) and the oil temp immediately falls. See attached plot. Two G turn at timestamp 13:14

Is it possible I'm un-porting the pickup in normal flight and starving the pump? Not enough oil in the sump? Pulling some G puts more oil at the pickup? I don't know what a Titan cold air sump looks like inside.

Right now I'm planning on adding a couple quarts and see what happens. I just hate to have it all end up on the belly.

Mahlon, are you out there? :confused: Need some expert advice.

Thanks
 

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So, your getting 60 PSI with hot oil at high RPMs and cranking the adjuster in all the way did nothing to change it and the ball / seat was checked for knicks and debris? If that is the case, I would suspect that there is less than designed resistance in the oil path downstream of the adjuster or a problem getting oil to the pump. Mostly likely guesses for a new engine would be the accidental omission of one of the internal galley clean out plugs (assembled by humans that are prone to mistakes) or a problem in the oil pickup circuit, either a restriction or something introducing air and both reduce the pumps output flow. The increase in pressure with positive G's is a bit confusing and makes me think that possibly there is a hole somewhere in the pickup system allowing air into the system and the G's are somehow changing things and covering the hole with oil and the pressure spikes up once the air is gone. Could also be a foreign object in the pan blocking the pick up input (creating the restriction) and it is somehow shifted with a lot of G's. If air is getting introduced, you should be able to identify it. Pull the dipstick immediately after a flight and look for foaming in the oil. If air is introduced in the pickup, the pump will create foamy oil (works like a blender) and due to the oils thickness, it takes a while for this to precipitate out.

The fact that you get the same 60 PSI at idle is also confusing. Pump volume should be way down at idle and we are seeing no drop in system pressure. This implies that the pump is producing good flow and there is adequate restriction downstream. It kind of points to a problem in the adjuster. Might pull that off and get an expert to look at it. It is quite uncommon to have a flat OP all the way from idle up to 2700, unless the spring on the adjuster is really loose.

I would definitely call Superior and start to get ahead of this as I don't feel that a brand new engine should be incapable of getting above 60 PSI with hot oil. Something somewhere is not right. Before doing this, I would put a mechanical OP gauge on to verify there are no instrumentation errors. I imagine Superior will demand this before addressing hte issue.

EDIT: after further thought, my first area of exploration would be the adjuster. The 60 PSI at idle kind of eliminates all of the issues I outlined in the first paragraph as I didn't initially look at your graph. The introduction of G's could be moving something in the adjuster that is causing it to briefly work as intended.

Larry
 
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Are the temp and pressure fluctuations reccurent when extra "G's" present??
Far from being an expert, I'm thinking loose/moving electrical connectors/wiring while pulling "G's" ???
 
Assuming your sensors and data is correct:

Looking at your data -the cause for oil pressure in cruise to be low is that the oil temp appears to be 220F.

I suggest you find out why the temp is high then check your oil pressure.


Thought A: IIRC, there was a Titan engine that had lots of carbon balls on the oil suction screen. That could restrict intake and G loads would improve that.
 
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Assuming your sensors and data is correct:

Looking at your data -the cause for oil pressure in cruise to be low is that the oil temp appears to be 220F.

I suggest you find out why the temp is high then check your oil pressure.


Thought A: IIRC, there was a Titan engine that had lots of carbon balls on the oil suction screen. That could restrict intake and G loads would improve that.

I pulled the screen, and it was okay.
As I noted, when I pulled 2 g's, the oil P went up and the oil T immediately came down 10 degrees. (214 to 204F) See area of plot at the 2g pull and the delta info box on the right. Agree. With the big cooler I would expect overcooling, and it definitely comes down with higher oil pressure, quickly.
 

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Since this is a new install I would be tempted to tee in a mechanical oil pressure gauge (typically oil-filled) and compare indications with the engine running. On my RV-3B I ran a 303 hose through the firewall and secured the gauge under the right side of the panel.
 
I pulled the screen, and it was okay.
As I noted, when I pulled 2 g's, the oil P went up and the oil T immediately came down 10 degrees. (214 to 204F) See area of plot at the 2g pull and the delta info box on the right. Agree. With the big cooler I would expect overcooling, and it definitely comes down with higher oil pressure, quickly.

Something else is going on here. At the marked area, OT drops only 10*, yet OP increases almost 15 PSI. Way more pressure increase than can be attributed to a 10* temp decrease. Definately possible that the increased pressure created more flow and that caused the temps to drop. Also note that later the OT stays low even though the pressure doesn't come back and this doesn't match up with what happened with the 2G event. This is not a normal temp / pressure relationship on the graph. The data between :17:00 and :20:00 shows a more typical temp pressure relationship.

Definitely G related. the rise is OP seems directly related to the amount of Gs pulled. First you pull 2 and then pull 1.6 and the OP rise seems to correlate well. Even the duration's of the OP fall matches the fall in Gs.

The OT begins to fall IMMEDIATELY with the onset of G's and IMMEDIATELY rises once the Gs are back to 1. To me that points to a possible instrumentation error like a loose ground strap. Don't believe that a thermistor potted in a brass shell can react that quickly, making me think that temp didn't actually move during the high G event, though it is possible that there was air in the system and once flushed out the sensor began to react. In many cases, both the OT and OP sensor are single terminal and rely upon the engine ground strap for conductivity back to the instrument.
 
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Break in oil.

NOTE: Use 50-weight, aviation grade mineral oil for engine break-in.
This is according to Continental Motors SIL 012 for your engine.
A 50-weight oil is equivalent to SAE viscosity grade 50.
You could use Aero Shell 100 single grade, (without any additives).
This is provided that outside air temp is between 60-89 F.
If outside temp is between 1-69F I suggest Aero Shell 80 single grade.
Using a multigrade oil under Break in of a new engine is NO, NO.

https://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/the-aeroshell book/_jcr_content/root/main/section/call_to_action/links/item0.stream/1661865089178/532117a417be92af6b0a951a304ada955d588ce5/theaeroshellbook-edition2021.pdf

Good luck
 

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Tags on the engine stated to use non-synthetic multi-grade.
Here is the guidance from Eci.
 

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Back to: why is it hot?

Can you show us some pictures of the oil cooler plumbing? If the CHT is good, then maybe the cooler is just not getting the full oil flow or no oil flow.
 
Can you show us some pictures of the oil cooler plumbing? If the CHT is good, then maybe the cooler is just not getting the full oil flow or no oil flow.

Don't have a lot of detail of that specific aspect. Standard in's and out's.
 

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May be time to check the Vernatherm.

Read the next post before you do that..
 
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I pulled the screen, and it was okay.
As I noted, when I pulled 2 g's, the oil P went up and the oil T immediately came down 10 degrees. (214 to 204F) See area of plot at the 2g pull and the delta info box on the right. Agree. With the big cooler I would expect overcooling, and it definitely comes down with higher oil pressure, quickly.

Oil temp will not change immediately. If your senders ground through the base, check the resistance from the sender case to the firewall to see it there is a breakdown in the ground path between the sender and the firewall on it's way to the battery. If two wire, check your ground location.
sensors.JPG
 
I would say there's some weirdness with the sudden changes in OT and OP with G's which as others have pointed out is likely some kind of wiring issue.

The OP relief valve controls how much oil is bypassing back to the sump. If the ball is seated such that there's not much leaking past the ball, and considering you've screwed it in, there could be excessive clearances somewhere or a plug missing inside the engine. I've seen that happen on an engine built by a very reputable shop where the prop wouldn't hold RPM.

Personally I am not a fan of squirters as they raise oil temps and aren't needed on a parallel valve Lyc.
 
concerned

I am a little concerned if the fault is a grounding issue, but you were turning the pressure setting thinking the gauge was accurate. The real oil pressure could be far out of range. Probably best to get a separate steam gauge hooked up and check oil pressure on the ground before any damage is done due to incorrect oil pressure settings.
 
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G3X with a GEA 24 EIS and sensors.
I doubt it is a ground issue, but I will double check the wiring for the oil pressure and temp sensors. And, I have a mechanical gauge on the way. I won't be able to check wiring and test until this weekend.
Thanks for the ideas.
 
You might take the time to inspect the oil cooler hoses. There might be an issue with blockage in them if they are new. Also, there have been instances of oil cooler hoses delaminating internally so the inner lining collapses or balloons inward when the oil travels through causing suction inside. That one is particularly insidious as it only happens when running above a certain RPM so everything looks fine on an internal visual inspection. This scenario would more likely apply to older hoses past their design life. I saw one that way and when the pilot pulled the throttle back to idle such as on final the oil pressure would go "up" rather than the expected "down". That was because at idle the ballooned inner lining of the oil hose would return to normal due to the lower RPM of the engine reducing the suction effect.
 
I thought I would post a follow-up to this thread in order to close it.
Here is what it was not:
  1. It was not the sender
  2. It was not the wiring
  3. It was not the ground
  4. It was not the hoses
  5. it was not the oil type
What it was.....[drum roll] was:
A lack of oil in the sump/system.
Yup. (Pretty much step #1 in the Lycoming low oil pressure debugging procedure, LOL)
I added two quarts to the four I drained out of the sump (did not replace the filter or drain the cooler) and the system regulated as expected, with no change due to g-loading, and not a lot of change with oil temperature. I also calibrated my dipstick, so that will ensure I don't repeat this situation.
I requested some photos of the interior of the Titan cold air sump, and upon inspection, this makes sense.
As you can see, the wide, flat sump does not have a "well" around the pickup port, so it is likely pulling down the local oil level (like a water well draw-down) and "slurping" instead of getting a good even drink.
The Superior cold air sump has a deep "well" in the back of the sump at the pickup point, and the Lycoming IO sump has a local depression around the pickup, at least that's what the photos I could find suggest.
So, if you have a Titan cold air sump, you will likely need to run a bit more oil than with the standard sump (which I had previously) or one of the other brands.
 

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Good news, Mike. I have Titan (legacy ECI w/standard sump) on my bird and have enjoyed all the extra maintenance/repair associated with the same, especially cylinders. Gives me something to do. Titan. The gift that keeps on giving.
 
Titan Today

Although Titan may be associated with old problems that were encountered when it was owned by ECi over 10 years ago, being part of Continental Aerospace is much different. Titan is a vastly different company division now and in a better one too. It would be a mistake to assume that the legacy from ECi is any reflection on the current part of Continental with it's long and successful place powering GA.

It would also be a mistake to denigrate a product when the problem was not with form, fit, or function but by an inadequate quantity level of oil !
 
Thanks for the final followup- the data perfectly matches the root cause. Not a shock really. I sure assumed it was topped based on the OP.

. . . I started with six quarts, and added a quart when it was down a half quart or so. I drained it today, and got exactly four quarts out of the sump. So, I'm assuming that the cooler and filter are holding a bit.
Thanks

But why was it reading low? I thought it was standard procedure to calibrate the dipstick on the first fill, it sure sounds like you did that.
 
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It would also be a mistake to denigrate a product when the problem was not with form, fit, or function but by an inadequate quantity level of oil !

Jim,
Agree. I was initially confused by the "Lycoming says it will run on 2.5qts just fine" mantra until I decided to go back to the basics. "when you hear hoof beats..." To be clear, it never lost oil pressure, it just wasn't regulating as expected.
My IOX370 pulls like a beast and hasn't missed a beat since first run. No complaints there.

Thanks for the final followup- the data perfectly matches the root cause. Not a shock really. I sure assumed it was topped based on the OP.

But why was it reading low? I thought it was standard procedure to calibrate the dipstick on the first fill, it sure sounds like you did that.

I did, sort of. Considering the initial fill of six quarts (what I always used on the O-360), then the filter and (large) cooler capacity after first run, I think I
just got down to a critical level for this engine way faster than I expected, and didn't compensate with enough "top off". I also think I have a less than ideal breather setup and am loosing some via that.
She's very happy with six in the sump.
 
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