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(A little) Oil dripping from the air filter after shutdown Lycoming IO-360A1A with Rajay Normalizer


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The Case

My Mooney got a (pretty) new engine, IO360A1A with a normalizer which was overhauled about 42 hours ago. I love the engine. After 30 hours it was uninstalled from the former aircraft it was filled to the top of the crankcase with oil (about 14 qt) and then stored properly. It also has a normalizer. Between the disassembly and the new assembly in my mooney it was stored properly for about 16 months.

I got it installed, added as surely and flew for about 12 hours now. The engine runs very well, besides it is a little bit rough at lower RPMs (magnetos and so on were checked). Temperatures are all in the green, EGT/CHT spread between the cylinders is minimal, power is good, it is obviously using no oil , there is no white smoke, no oil in the exhaust and no oil in the breather tube. The belly and everything under the aircraft stays clean.

 

The Problem and the symptoms

But there is one exception. After I shutdown, some oil drips from the air filter. I have the M20E, with the air filter in the middle of the cowling and actually there is a Challenger air filter installed. The amount dripping is approximately 15-20 drops. Visible but nothing serious. The dripping oil is (already) cold directly after shutdown. It looks "fresh" and has a nice golden appearance. The oil in the oil pan also looks fresh after the 10 hours (golden). So I think there is no blowby. The oil also does not smell "burned".

The oil does not come from the normalizer, as intake and pressure side of the turbo are perfectly clean. So I am sure there turbo does not overflow in oil. Also all valves to the Rajoy are installed properly and the flow test of the scavenger pump is fine.

After uninstalling the air filter I found out that it seems like the oil comes from the intake/fuel mixure as it seems to run through the pipe from the Rajay Airbox (behind the little flap) to the mixer.

One factor which may be of interest is, that during take off, with oil about 120° Fahrenheit my oil pressure is really high (up tp 105 PSI) while with "hot oil" at around 180 - 190° Fahrenheit oil pressure is in the middle of the green. But looking in the Lycomin maintenance manual I cannot see any oil line which may be able to leak to the intake due to high pressure.

 

What I checked and considered to far

I checked what could be the cause:

  • Worn/broken pistons rings: But power and pressure as well as temps are good on all cylinders. There is no blowby. Not burning oil. Belly of the plane is perfectly "dry" and no relevant oil (not linke my older engine which spit a lot on the belly).
  • Worn or not proper sitting intake valve: But this would not explain, why it drops as the oil had to come from somewhere and in the cylinder there is normally no oil which could then be "pushed" in the intake I guess. Also there is no plug fouling or anything. Colors of spark plug is nicely "light brown"
  • Turbo overflowing: Lines to and from the turbo are perfectly dry.

I now checked the Lycoming manual and the pipes for the intake go directly through the oil pan. Nevertheless there is no "physical connection" and no "seal" and if there was a leak or sth (like a crack) I'd expect that oil is running pretty much all of the time or at least if it was temperarture related it had to "drain" during flight, either in the cylinder (being sucked there with the air) or significantly more in the intake system. I'd also expect that I have a significant oil loss then. Actually it was I guess about maybe half a qt in 10 hours what I lost while flying.

I also wonder if it may be some kind of "rest" after the engine was drained in oil (14 qts) for storage. Then it should be gone after a while but I have no clew how long this would take. Does anybody know if 14qts is enough, so the cylinder was in oil totally and some oil could have left through the intake pipes and may now be dropper in the intake?

A factor may also be the challenger air filter. Its side seal to the cowl is very poor and this is where the oil "drops" out. As the amount is little with a better seal and maybe with the "old air filter" it may not even be visible. But still I did not have it with my old engine (and the same air filter).

The oil dripping also seems to be a little bit "gluey" so it has some kind of "glueing" consistency, a little bit like "camguard". And it is "cold", so even directly after engine shutdown when it slowly starts to "drop", it as no relevant temperature.

 

The Quest

I talked to different mechanics but so far did not get any satisfying answer besides wait and see. Does anybody have an idea what to check next and what may be the reason? Did anybody discover sth like this already? Or does the swarm intelligence of the forum finally agree, that it may just be a matter of time until it is all "drained" and little sums of oil make a big mess?

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I have the same air filter, had the same thing but mine was from a recently serviced air filter cleaning and re wetting....it was just a bit too much fluid on the filter and it stopped soon afterward....maybe that is why the fluid is cool and clean...are you sure its engine oil?  If it is sticky it is not engine oil and certainly the fluid that is put on the air filter.

good luck

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1) Check to see if you have the same issue Jim is describing above...

Some air filters get wetted with oil... yours might be one... the oil helps block stuff from getting through...

2) If you were getting oil delivered to your air intake...

  • that would be bad...
  • the oil level would be noticeably lower with time...
  • the smoke show out the tail pipe would have mosquitos running away...
  • the drips out of the tail pipe would be pooling on the floor...

3) Your mechanic should remember when he piled the air filter... ask.

4) The wait and see approach applies to waiting for the oil on the filter to stop dripping... because it will.

5) If oil is missing from the sump, or showing up in the exhaust, or running down the belly all the way to the tail... or crusting over the spark plugs like crazy...

Take pics and post them here for further discussion...

6) expect the airflow to be unidirectional...  oil doesn’t like to flow upstream.

7) To prove the direction the oil is coming from... clean the intake.  Run the engine... see if there is any oil in the intake...

8) Sniffle valve is intended to have air and or fuel in it...  if you find oil...  that would be another confirming bad sign...

PP thoughts only, not a mechanic...

Best regards,

-a-

 

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I will check for the issue Jim described. But as is is the same filter as before, I can hardly imagine why it should drip now besides maybe that the temperatures due to the normalizer installation got higher and therefore the oil now partly drips. On the other side, I had taken the oil filter away and the oil was in the upper air chamber of the Rajay (directly oder the oil filter). As the oil may not "jump up", it has to come from the top.

The engine has absolutely no "white smoke". It runs clean. Absolutely no oil on the belly and no oil at the tail pipe.

So far I do not find any oil missing. The engine uses little oil. I found in the Bonanza-Forum that this seems to be common with some engine and may be gone over a while or maybe not. There are some who write that even after 600 hours, there is still some oil dripping and some that say after 20-30 hours it is gone. They explanation was that this is conservation oil.

On the other side it was also written, that these may be leaking valve guide seals. But shouldn't there be white smoke then?

I guess next is to take off the lower cowling and take a good look into the intake system.

Ingo

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Let’s see if Rich is around here... he is more familiar with the turbo installation... @N201MKTurbo
 

When valve guides leak...

They typically send a drop of oil into the cylinder after shut down..

A puff of white smoke upon start-up could be expected...

The lower spark plug will probably get oil on it...

Enough oil entering the cylinder will tend to leave crusty burnt crud on the spark plug blocking the air/fuel flow around it...

If you have an engine monitor... be on the look out for any skipping in the lower spark plugs...

 

If you have time... pull the lower spark plugs and inspect them... that will give a clear hint if oil is getting into the cylinders...

Its an interesting challenge... any source of oil can be suspect... including the oil from the long storage.

Storage oil is typically different from regular engine oil... it doesn’t flow much at ordinary daytime temperatures...  it may be showing up from someplace that is only getting warm enough while running...

PP thoughts only, not a mechanic...

Best regards,

-a-

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Well, here I am lounging in a beach hotel in Santa Barbara. The first cross country on my newly rebuilt engine. The ironic thing is that the last flight before I tore the engine down was to Santa Barbara. I’m here working for the Intelligence and Space division. But I digress,

I have been following this discussion, but can’t think of anything that would cause the filter to leak oil unless the turbo was up chucking oil into the intake, but you say that it is clean, so that is unlikely. You said it fits loosely into the airframe, so is it a random leak that is exiting the cowl at the filter? Other than that , I have no idea.

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@carusoam

Thanks for the input. EDM-Data is all good (EDM 900). Mag-Tests are smooth. No white smoke, neither with start, nor at any other time. Turbo is dry like a dessert. It definitely comes "from the top", so from the Rajay Airbox. I like this challenge also ;) (even as it tends to be a little bit annoying)

 

@N201MKTurbo

Santa Barbara sounds like a good option. Cold and Rainy here in Nuernberg, Germany. The air filter has the inner bracket with the filtering mesh and an outer "mount" which with the Challenger consist of a rubber seal and a flat metal frame which is screwed on the cowling with six screws. The production quality of this mount is moderate at least and the shape does not fit perfectly to the cowling. There is no risk of dirt or dust getting in as the inner filter bracket fits "tight" to the side of the cowl but the rubber seal does not prevent any oil from passing by. I will try to take a pice. Just may take about 1 1/2 weeks as I am getting the seats redone.

 

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As it is not yet running (interior is redone) I can only send the pic of the air filter bracket so far. On the side view (left picture) you can see the "non-optimal" fit (was the same with two different cowlings). On the other picture (right one) you can see where the oil "runs" after shutdown (shiny spot left) which is the side of the filter facing the front gear. Will take some more pics as soon as practical.

Ingo

 

 

IMG_3220.jpeg

IMG_3221.jpeg

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From looking at the pic, my guess is you have an oil leak somewhere and it’s showing up there, it’s not coming from inside of the engine.

And that is some very clean oil

Edited by A64Pilot
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So.... if it is a foam filter insert.... and it was soaked with oil.... there might be a lot of oil in the foam filter....

There is a procedure for oiling a filter... see if the procedure was followed... it will give an amount of oil to be used... it may be a TSP?

The cleanliness of the oil that A64 mentioned, may be a good hint of its origin...

Doesn’t look like a lot of screws were used to hold the retainer in place...  at cruise speeds it probably changes shape...

 

PP thoughts only, not a mechanic...

Best regards,

-a-

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I would look at your filter, did they use the proper K&N spray, or just oil it up? When new, some overly soaked foam bracket fliters leave a heck of a mess. Front crank seal(you did say high oil pressure) ? Prop gov oil line loose and dripping ? Case mating issue up front? 

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I have a m20e with the rayjay turbo normalizer and the same intake system and filter.  I have seen oil from a new filter do exactly what you are speaking about.  Often I have a stickey coating of filter oil underneath the intake airbox on the bottom cowling.  I would verify the oil type before making yourself crazy.

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