Managing Expectations after FOH - oil leak

[kep5niner]

I had my #1 engine FOH this past spring. After every flight, the underside of the cowling, exhaust, gear doors, etc. are an oily mess. The #2 side leaks to an extent as well, but not nearly as bad. I go 25-35 hours between oil changes, with no measurable oil loss. I do my own oil changes, and clean the engines up as close to spotless every time. However, the #1 engine is leaking more than I think a recently FOH engine should.

I've taken it back to the shop that did the FOH once to try to correct it, to no avail. I'm of the mind that the "new" engine basically shouldn't leak a drop of oil.

Is this something I just need to live with, or am I within my rights to hold the shop's feet to the fire? I've put about 150 hours on the engine since the FOH. Thanks.

 

[sourdough44]

The shop should be all over it, if not, do it yourself. I’d clean up the area, once clean, start, run some, maybe taxi, and find out where EXACTLY the leak is from.

Once that is known, take it to the shop that did the work. As a secondary, put up a stink on social media.

OBTW, I have an almost new Lycoming, doesn’t leak a drop of oil.

 

[Radar Contact]

How much oil are you filling it with? I do 10 quarts at change and keep it around 9 between changes and it’s great. If I do more, it pukes it out.

If it’s for sure not related to over-filling (book values are typically too high and they all seem to have their own sweet spot) then I’d be wanting to get to the bottom of it.

What kind of warranty/agreement did you have with the shop?

 

[NordicDave]

How much oil are you filling it with? I do 10 quarts at change and keep it around 9 between changes and it’s great. If I do more, it pukes it out.

If it’s for sure not related to over-filling (book values are typically too high and they all seem to have their own sweet spot) then I’d be wanting to get to the bottom of it.

This was my question as well. Need to find the engines oil level happy spot. Mine is rated for 12 quarts and anything over 9.5 is jettisoned onto the belly. Certified engines are rated to operate on half capacity. I would not run at half capacity, but gives a comfort margin that less than full is OK and actually preferred if it just gets dumped overboard any way. I'd suggest recording the oil level after an extended flight and leave it there for the next flight. If it depletes overboard at the same rate, might have an issue with the overhaul. If it remained constant or a half quart down, that maybe your engines oil level happy spot.

 

[kep5niner]

I fill the engines to 10 qts., and that’s where they stay all through the oil change interval - couldn’t be happier in that regard. I know a tsp. of oil at 180 KTS can appear worse than it is (kind of like blood in water).

Just after the last oil changes, once clean, I flew straight to the shop for them to try to track down the leak. They thought it was the starter adapter seal, so R&R that. I took a turn around the patch, and they inspected. Still a mess again, but they assured me that was “residual” oil. Well, I’m 30 hours later and even after clean up, the residual oil still ended up everywhere...

I’ll have to review the PO for the engine work - I was still overseas when the FOH was done. It was the most paper-work “light” contract I’ve ever engaged in. For the $$$, I should have my head checked, but I felt comfortable following my A&P’s input.

That’s good to know that there’s engines out there that don’t leak a drop - so it is possible. l was going to knock out the oil changes on Wednesday, though now my wife tells me there’s some big parade we’re going to (go Chiefs!!!), so probably Thursday. I’ll take a closer look, run up and do a few turns in the pattern until I can find the source, then be back on the doorstep of the engine shop.

Thanks for the input fellas.

 

[Let'sgoflying!]

Rocker cover seals
Pushrod seals
Any accessory
Any fitting/line/hose
Oil pan
Case seams
Case cracks

 

[RSFTucson]

May I ask what type of oil filter you have.
Tempest, or Champion?
I am chasing a leak as well, and I believe it is the oil filter.
Regards,
Randy

 

[455 Bravo Uniform]

Odd enough, I had a dipstick tube that was not tightly bottomed out in the block. It was slowly working itself out. Consequently, the dipstick always showed low and I would overfill it. It took my first oil change to figure it out.

I also replaced the oil cap gasket and oring on the dipstick.

 

[Bell206]

’ll take a closer look,

An old maintenance trick to track mysterious oil leaks is to use a visible dye penetrate developer. It's basically a powdery substance in a can. After cleaning the engine and cowling very well, once the cowling is dry, spray the interior areas of the engine cowls first. After the spray dries install the cowls and perform a ground run of a set amount time and shutdown. Look over the powdered areas for signs of oil. Just keep in mind this stuff is designed to pull inspection dye out of hair-line cracks so it will also pull out any residual oil/solvents from metal seams, etc. Repeat with longer runs. If no joy then move to taxing, etc. It can be rather time consuming but it's one method. Once you get a general hit of where the leak may be you can narrow it down with the same process. The developer is not cheap and I've seen people use baby powder, etc in its place. But I found this stuff sticks better. There are also some oils that have a UV footprint that will show with a UV blacklight flashlight. However, I don't know sure if any of the popular recip engine brands are.

 

[mondtster]

That’s good to know that there’s engines out there that don’t leak a drop - so it is possible.

Depends on what you mean by "don't leak a drop." They all seep after they get a few hours on them but you should be able to get the engine pretty dry. Keeping it that way can be a full time job however.

I've usually been able to find the leaks without resorting to the developer trick that Bell206 suggested but it is a good option if necessary.

 

[kep5niner]

May I ask what type of oil filter you have.
Tempest, or Champion?
I am chasing a leak as well, and I believe it is the oil filter.
Regards,
Randy

I've got filter screens, so no removable filter per se. I can confirm that the two areas I manipulate during the oil change - the drain plug and filter screen - do not show any signs of leaking. So I got that part right

 

[Stewartb]

Maybe. Pressure cowls can make oil leaks very difficult to find. Where you find it may not be where it originates from. Locate the source, then deal with it.

Continental or Lycoming?

 

[kep5niner]

Continental IO-470. This was an AK bird for over 10 years - maybe you recognize her?!

 

[Stewartb]

I pay little attention to non-conventional airplanes.

Push rod tubes would be my first place to look. Easy to find after sitting a day or two. Easy to fix. The other thing I'd look for is a whistle slot in the crankcase breather. If the slot is too big and/or the breather outlet isn't in a negative pressure flow the crankcase mist blows into the cowl.

 

[David Megginson]

I had my #1 engine FOH this past spring. After every flight, the underside of the cowling, exhaust, gear doors, etc. are an oily mess. The #2 side leaks to an extent as well, but not nearly as bad. I go 25-35 hours between oil changes, with no measurable oil loss. I do my own oil changes, and clean the engines up as close to spotless every time. However, the #1 engine is leaking more than I think a recently FOH engine should.

I've taken it back to the shop that did the FOH once to try to correct it, to no avail. I'm of the mind that the "new" engine basically shouldn't leak a drop of oil.

Is this something I just need to live with, or am I within my rights to hold the shop's feet to the fire? I've put about 150 hours on the engine since the FOH. Thanks.

15 years after my overhaul in 2005, my Lycoming O-320 still doesn't leak any oil: the inside bottom of my cowling is still clean and dry (not slippery). What you're experiencing does not sound OK.

Right after that overhaul, I took the plane for a long test flight to burn in the new cylinders. Fortunately, I'd been in the habit of tracking my fuel consumption after every flight, and I noticed I'd burned far too much fuel. I taxied straight back to the local shop that installed the overhauled engine, we opened up the cowling, and found fuel staining in the bottom—they had not tightened a fuel line properly. They fixed that immediately (for no additional charge, of course, and with many apologies), and it's been fine since.

When you see a problem right after overhaul, get it onto it fast, and don't let the shop get away with shrugging it off! If I hadn't noticed the elevated fuel consumption, I could easily have run out of fuel on a long cross-country, if not ignited an engine fire. It turned out to be an easy fix. Your problem could be that simple, too, and I'm sorry it's so hard to get the shop to take it seriously.

 

[455 Bravo Uniform]

Check that your dipsticks are correct. IO-470 in my bird, see my post above.

Plus, in your twin, are the dipsticks different due to canting of the engine on either side? Maybe you got a wrong dipstick or they were swapped sides? That would explain a few quarts going overboard.

 

[edo2000]

I fill the engines to 10 qts., and that’s where they stay all through the oil change interval - couldn’t be happier in that regard. I know a tsp. of oil at 180 KTS can appear worse than it is (kind of like blood in water)....

This is a tough one. I recently solved a small, annoying, leak on my Lycoming with new rocker cover seals (rubber, not cork). I would definitely echo what others have said about oil levels. I would try filling your #1 engine to 8.5 quarts on the next oil change. Run it that way for a few hours and see if it affects the amount of oil you see on the belly. Did the engine leak any oil at 10 qt. levels before the OH?

 

[mondtster]

Push rod tubes would be my first place to look.

Same here. When the pushrod tubes leak (and they will) it will make a mess and sometimes the oil migrates quickly making the source hard to determine.

 

[kep5niner]

This is a tough one. I recently solved a small, annoying, leak on my Lycoming with new rocker cover seals (rubber, not cork). I would definitely echo what others have said about oil levels. I would try filling your #1 engine to 8.5 quarts on the next oil change. Run it that way for a few hours and see if it affects the amount of oil you see on the belly. Did the engine leak any oil at 10 qt. levels before the OH?

That's a good question, that unfortunately I don't have a good answer for. I was overseas when I procured the aircraft, performed the typical pre-buy, etc. I had it flown to my hangar. Shortly thereafter, I had it put into annual before I returned state-side. That's when I got the call about needing the overhaul, so I don't have any personal historical reference for what the engine took preceding the OH, except for all the previous log book entries showing 10 qts serviced.

Same here. When the pushrod tubes leak (and they will) it will make a mess and sometimes the oil migrates quickly making the source hard to determine.

Good tip, and I will examine the pushrod tubes closely when I change the oil and clean up the engines this week.

I appreciate all of the feedback and input!

 

[Chip Sylverne]

An old maintenance trick to track mysterious oil leaks is to use a visible dye penetrate developer. It's basically a powdery substance in a can. After cleaning the engine and cowling very well, once the cowling is dry, spray the interior areas of the engine cowls first. After the spray dries install the cowls and perform a ground run of a set amount time and shutdown. Look over the powdered areas for signs of oil. Just keep in mind this stuff is designed to pull inspection dye out of hair-line cracks so it will also pull out any residual oil/solvents from metal seams, etc. Repeat with longer runs. If no joy then move to taxing, etc. It can be rather time consuming but it's one method. Once you get a general hit of where the leak may be you can narrow it down with the same process. The developer is not cheap and I've seen people use baby powder, etc in its place. But I found this stuff sticks better. There are also some oils that have a UV footprint that will show with a UV blacklight flashlight. However, I don't know sure if any of the popular recip engine brands are.

Athletes foot spray works good too, and is a buttload cheaper. Arroshell 100 + glows pretty well too, right out of the bottle, no additive required.
Yeah, I've chased down a few leaks....also look close at the drain back tubes to see the clamps are tight.

 

[mondtster]

....also look close at the drain back tubes to see the clamps are tight.

There aren't any on a continental. Oil drains back down the pushrod tube.

 

[Dan Thomas]

An old maintenance trick to track mysterious oil leaks is to use a visible dye penetrate developer. It's basically a powdery substance in a can. After cleaning the engine and cowling very well, once the cowling is dry, spray the interior areas of the engine cowls first. After the spray dries install the cowls and perform a ground run of a set amount time and shutdown. Look over the powdered areas for signs of oil. Just keep in mind this stuff is designed to pull inspection dye out of hair-line cracks so it will also pull out any residual oil/solvents from metal seams, etc. Repeat with longer runs. If no joy then move to taxing, etc. It can be rather time consuming but it's one method. Once you get a general hit of where the leak may be you can narrow it down with the same process. The developer is not cheap and I've seen people use baby powder, etc in its place. But I found this stuff sticks better. There are also some oils that have a UV footprint that will show with a UV blacklight flashlight. However, I don't know sure if any of the popular recip engine brands are.

Amazon has it.