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Engine recently seems to be leaking oil


BrianW

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Hi,

I have a 1979 M20J with a Lycoming A360 engine, approx 1000 SMOH.  I have it serviced at a MSC.   The oil is tested each time I have it changed and everything has been normal.

However, since my last oil change last July to now the engine started to leak oil at cylinder 4 by the guide tubes and slight leak around cylinder 1 exhaust manifold.  The lower spark plug on cylinder 4 regularly is oil fouled but I can clear it at run-up.  At my tie down there are no noticable oil drip spot.  The engine breather tube seems wet but that could be the oil dripping on the tubes from cylinder 4 above.

The senior mechanic says the oil leak is very small and not to worry about it.

This is my first plane and I've had it for 2 years.  Coming from an automotive background seeing an engine leak oil bothers me.  I keep my plane clean and now the belly has oil and exhaust marking. 

I've attached a picture of the white belly panel (looking towards the tail) before it was removed for its annual.

The exhaust stain may not be related because the exhaust pipe was rotated a bit closer to the belly last annual since the exhaust pipe was interfering with closing the cowl flaps during flight.  The exhaust pipe doesn't have much of a bend at the tip so the exhaust isn't blowing as far away from the plane as before.

I am told the tiny amount of oil leaking at cylinder 4 isn't worth the estimated $1500 to have the cylinder pulled at this time.  He suggests I add wiping the belly after flights for now (he said it was something he had to do with his 172).

The mechanic and the shop know I don't have deep pockets.  And this annual is going to be very expensive already with us replacing the old instruments with a JPI EDM900 and CIES fuel senders.

I'm on the fence on what to do.

Financially, I can't do all the work I want in one visit. 

I prioritize the things that must get done over the things I want to get done.   I then I do the tasks that need to get done,  and if funds allow, I'll tackle a few of my wants. 

With the JPI, I hope the I can more  accurately lean the engine to prevent running rich, which may help with the exhaust stain (perhaps even help with the oil consumption).

 

20190115_104844-2265x1523.jpg

Edited by BrianW
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It is ugly, but it will reliably run like that for years.

Airplanes are like dogs, they like to mark their territory.

If you don't want to spend your money then don't.

Keep an eye on the oil leaks. inspect to see if you have a cracked case.

When you cannot clear the fouled plug, then fix the cylinder. 

When you get tired of the leak you will fix it.

Just make sure you don't run out of oil.

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My engine had a cracked case, which I didn’t know about despite mentioning the oil leak to 3 different IAs. They never could figure out the source because the oil gets splashed around during flight. I put 700 hours on it with this problem, wiping down the nose gear and belly after a flight was routine.


Tom

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3 hours ago, BrianW said:

Hi,

I have a 1979 M20J with a Lycoming A360 engine, approx 1000 SMOH.  I have it serviced at a MSC.   The oil is tested each time I have it changed and everything has been normal.

However, since my last oil change last July to now the engine started to leak oil at cylinder 4 by the guide tubes and slight leak around cylinder 1 exhaust manifold.  The lower spark plug on cylinder 4 regularly is oil fouled but I can clear it at run-up.  At my tie down there are no noticable oil drip spot.  The engine breather tube seems wet but that could be the oil dripping on the tubes from cylinder 4 above.

The senior mechanic says the oil leak is very small and not to worry about it.

This is my first plane and I've had it for 2 years.  Coming from an automotive background seeing an engine leak oil bothers me.  I keep my plane clean and now the belly has oil and exhaust marking. 

I've attached a picture of the white belly panel (looking towards the tail) before it was removed for its annual.

The exhaust stain may not be related because the exhaust pipe was rotated a bit closer to the belly last annual since the exhaust pipe was interfering with closing the cowl flaps during flight.  The exhaust pipe doesn't have much of a bend at the tip so the exhaust isn't blowing as far away from the plane as before.

I am told the tiny amount of oil leaking at cylinder 4 isn't worth the estimated $1500 to have the cylinder pulled at this time.  He suggests I add wiping the belly after flights for now (he said it was something he had to do with his 172).

The mechanic and the shop know I don't have deep pockets.  And this annual is going to be very expensive already with us replacing the old instruments with a JPI EDM900 and CIES fuel senders.

I'm on the fence on what to do.

Financially, I can't do all the work I want in one visit. 

I prioritize the things that must get done over the things I want to get done.   I then I do the tasks that need to get done,  and if funds allow, I'll tackle a few of my wants. 

With the JPI, I hope the I can more  accurately lean the engine to prevent running rich, which may help with the exhaust stain (perhaps even help with the oil consumption).

If you are confident the oil is coming from the cylinder and not elsewhere, realize that aircraft motors are, in a way, REQUIRED to leak oil.  The huge cylinders compared to cars need significantly more oil to lubricate the piston, and a small amount of oil can make a huge mess.  It sucks if you like your plane clean, but that's the way it goes with these massive air-cooled cylinders.  The motor will not make significantly less power or anything if it's just leakage from cylinder wear so it wouldn't be a safety issue. 

If you suspect some kind of damage, on the other hand, you or your A&P can remove a spark plug and borescope the inside to check.  That's the only non-invasive way of checking things visually.

As an aside, the IO-360 A3B6 (I assume that's what you meant) has a sump volume of 8 quarts, but they tend to blow out anything about 6-7 quarts out the breather tube pretty quickly.  I tend to keep the oil level around 6 quarts unless I have a long trip (I know I lose about a quart every 8 hours).

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My '84 J marks her spot every time she is parked somewhere for over 8 hours out of the oil breather. She had other leaks, but over the past few years, my mechanic traced them down one at a time and fixed them. You might consider attacking one leak at a time - based on which one worries you most and is compatible with funding - and work on it.

Check whether you have fine wire or massive electrode plugs on the bottom of your cylinders as the fine wires seem to be less prone to oil fouling.

As for the exhaust staining, there is a product called "Rejex" that seems to do a fairly good job at allowing the stains to be wiped off with less effort than they normally require. Should work well on the oil streaking as well.

 

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1 hour ago, Oldguy said:

As for the exhaust staining, there is a product called "Rejex" that seems to do a fairly good job at allowing the stains to be wiped off with less effort than they normally require. Should work well on the oil streaking as well.

Aerocosmetics Wash n Wax is also very good for whatever is on the plane--oil, exhaust, bugs, etc. I clean my one-piece belly at annual using the red Degreaser, takes me about four minutes. Doing the whole plane with Regular [blue] formula takes much longer, because it is so much more area. Works great, much less work than wax.

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3 hours ago, Hank said:

Aerocosmetics Wash n Wax is also very good for whatever is on the plane--oil, exhaust, bugs, etc. I clean my one-piece belly at annual using the red Degreaser, takes me about four minutes. Doing the whole plane with Regular [blue] formula takes much longer, because it is so much more area. Works great, much less work than wax.

+1

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5 minutes ago, Kris_Adams said:

Ok, I need to break down and get some of this stuff.  Who’s the best source?

I buy it online from washwax.com but looking for the website just now, it's the same price at Spruce and Sportys (compare shipping costs, I didn't get that far just now). Blue for the whole plane, red for the belly. Just not for the windows . . . .

You'll need rags, too--I apply with one washcloth (which gets really dirty), and several white handtowels to buff dry. One towel will generally buff from the spinner out to one wing tip, then towel number two along the back of the wing and fuselage to the tail. Then I'm done . . . Let them dry and start again after my arms recover. I buy bulk towels / washcloths on sale.  :P

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20 minutes ago, Kris_Adams said:

Ok, I need to break down and get some of this stuff.  Who’s the best source?

 

7 minutes ago, Hank said:

I buy it online from washwax.com but looking for the website just now, it's the same price at Spruce and Sportys (compare shipping costs, I didn't get that far just now). Blue for the whole plane, red for the belly. Just not for the windows . . . .

You'll need rags, too--I apply with one washcloth (which gets really dirty), and several white handtowels to buff dry. One towel will generally buff from the spinner out to one wing tip, then towel number two along the back of the wing and fuselage to the tail. Then I'm done . . . Let them dry and start again after my arms recover. I buy bulk towels / washcloths on sale.  :P

I got mine off Amazon Prime. I use a lot more of the Blue so it was nice to get the gallon jug to refill the spray bottle.

https://smile.amazon.com/gp/product/B00X04JRMU/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

https://smile.amazon.com/gp/product/B003VSAS1O/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

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1 minute ago, Skates97 said:

 

I got mine off Amazon Prime. I use a lot more of the Blue so it was nice to get the gallon jug to refill the spray bottle.

https://smile.amazon.com/gp/product/B00X04JRMU/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

https://smile.amazon.com/gp/product/B003VSAS1O/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

Yep! Blue by the gallon, with a spray bottle. Just a quart of Red wil last longer . . .

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37 minutes ago, FastTex said:

You won't be disappointed. As everybody else mentioned above, I have been using the blue and red for years. I basically wash the plain with blue and use the red for the darker/tougher spot. May I also suggest the belly wash? For me #1! https://www.aircraftspruce.com/catalog/cspages/aerobellywash.php

 

I use the Red for the belly. Works great!

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14 hours ago, Skates97 said:

 

I got mine off Amazon Prime. I use a lot more of the Blue so it was nice to get the gallon jug to refill the spray bottle.

https://smile.amazon.com/gp/product/B00X04JRMU/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

https://smile.amazon.com/gp/product/B003VSAS1O/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

+1

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Bryan, I’m rather anal when it comes to oil leaks and I’m only satisfied when I find the source. When I bought my J it had a small leak at what I thought was the passenger side rear of the engine. The bottom of the fill tube appeared wet. Looking through the logs that fill tube was removed and resealed several times so I started looking elsewhere. It turned out there where two small return hoses under the cylinders and one had a stripped hose clamp so it wasn’t doing it’s job. I replaced it and the oil leak went away. My engine is now pretty dry and I’m satisfied. Just keep cleaning and looking, you’ll find the source and you’ll feel good knowing it’s fixed.

Edited by nels
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3 minutes ago, nels said:

Bryan, I’m rather anal when it comes to oil leaks and I’m only satisfied when I find the source. My J had a small leak at what I thought was the passenger side rear of the engine when I bought it. The bottom of the fill tube appeared wet. Looking through the logs that fill tube was removed and resealed several times so I started looking elsewhere. It turned out there where two small return hoses under the cylinders and one had a stripped hose clamp so it wasn’t doing it’s job. I replaced it and the oil leak went away. My engine is now pretty dry and I’m satisfied. Just keep cleaning and looking, you’ll find the source and you’ll feel good knowing it’s fixed.

When I know where the oil leak is it doesn't bother me as much, it's the ones that I can't figure out that make me nervous...

7 minutes ago, Oldguy said:

And don't forget to use smile.amazon.com with the Mooney Summit named as the charity if you want to help out.

Yes! It is easy to set up and once you do if you go to amazon.com instead of smile.amazon.com it will prompt you to go to the smile site. It does not work if you are using the app on a phone, but that is easy to work around. Just put everything in your cart with the app, then open the web browser on your phone and go to smile.amazon.com. It will all be in your cart, you can place the order, and the Mooney Summit gets the benefit.

Either I order too much on Amazon or we need to get more people using the smile link and setting up the Mooney Summit as the charity. I shouldn't be making up close to 5% of what has gone to the Mooney Summit...

image.png.4bf7dbef4b15ad06b9e8ce94bc1aa7c9.png

 

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8 hours ago, Skates97 said:

Either I order too much on Amazon or we need to get more people using the smile link and setting up the Mooney Summit as the charity. I shouldn't be making up close to 5% of what has gone to the Mooney Summit...

LOL, you order a lot from Amazon.  I just checked mine, 55 orders for $14.08 donated.  To be fair we have way more orders so mine would be higher but my wife has her own charity that here smile.amazon goes into.

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Check the clamps on the oil return tube from the rocker cover.  They are a pain to get to, but will usually show a drip if they are loose.  If they are still the thumb screw type, you can put the right sized socket over them to tighten.  don't go crazy with the socket. The A1A cylinders are 2 AMU new/ .5 rebuilt.    It's a lycoming it's just marking it spot.

Does not look like you can run the BY plugs that have a longer nose.

Yours if putting out a bit more oil than mine.   My number 4 is also the oily one.  

Goop hand cleaner and a roll of blue towels will clean up the belly

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Bryan, if you are keeping score...

  • Some oil leaks are easy to find and fix...
  • None are well appreciated...
  • Engines are not designed to leak... they just do over time...
  • Some oil return lines are easy to swap out... and seal replacement for valve covers takes a few minutes...
  • Some seals under appliances like the Governor are pretty easy to replace...
  • Some seals require to be replaced at OH...  that tiny silk thread between case halves....
  • Then there is a case crack... that’s a pain.

Some Mooney engines may actually still have cork used as valve cover gaskets... cork compresses and doesn’t bounce back very well...

Try to find out where the oil leak actually is... fix it if able... live with it if you have to.

Thanks GB for the awesome pics!

Best regards,

-a-

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