Stupid oil filler tube

Ed Haywood said:
Thanks. Yeah, I am somewhat obsessive about it. I wash it with mineral spirits at every oil change.
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I've heard others state they clean with mineral spirits. I use mineral spirits to hand clean grease/oil, but never felt comfortable just spraying it on an engine.

How exactly do you do it?
 
Domenick said:
I've heard others state they clean with mineral spirits. I use mineral spirits to hand clean grease/oil, but never felt comfortable just spraying it on an engine.

How exactly do you do it?
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With an engine cleaning gun. Just spray it on gunky areas to wash away.


I prefer it over citrus or phosphate based solvents because it is petroleum based and less corrosive. It also evaporates much faster than water, so you don't have to worry about little pools staying behind in crevices.

Why are you uncomfortable with it?
 
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The typical flaw with overtightened crush washers happens because they get reused. If a solid copper washer, anneal it prior to reinstalling.
 
Stewartb said:
The typical flaw with overtightened crush washers happens because they get reused.
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Agreed. I keep a stack of fresh ones on hand for checking my oil suction screen.

It can be a little tricky to seal with an inverted oil system. The hose wants to make it walk a bit.

BTW the Lycoming guy giving their Oshkosh presentation on owner maintenance joked that part of their overhaul log was "removing factory gasket from suction screen".
 
Right now a bunch of readers are scratching their head wondering what a suction screen is.

Ditto on having crush washers on hand. Finding them is the challenge!
 
kyleb said:
I feel your pain. It is incredibly frustrating when you misdiagnose something then repeatedly fix the wrong thing while the problem rocks on. BTDT too many times.
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Yep. The internet suggests my mistake is fairly common. The oil seeps out of the regulator. Air flow pushes it down and back, where it collects at the base of the dipstick tube and on the flange between the case and sump. My mistake was always checking after flying a while and waiting for it to cool. Yesterday I cleaned it, cranked it up, took one lap in the pattern, then immediately decowled and checked. The oil had not had a chance to run down past the dipstick tube and was pooled above it.
 
Domenick said:
I've heard others state they clean with mineral spirits. I use mineral spirits to hand clean grease/oil, but never felt comfortable just spraying it on an engine.

How exactly do you do it?
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Yeah, it seemed kind of shocking to me, too. Not something I've ever seen done in automotive or ag world. The shop that works on my plane buys the stuff in 275 gallon ibc totes. Pretty much the first step in any service they do is wash the engine. I think airplane mechanics don't like to get greasy.
 
Ed Haywood said:
Why are you uncomfortable with it?
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Atomizing a flammable hydrocarbon presents a huge risk of fire. Make sure there are no ignition sources anywhere.

That solvent also softens the insulating varnish in generators and alternators. It dissolves carbon brushes in those components and creates a resistive sludge on the commutator or slip rings and you lose generating power. It gunks up the carbon vanes in open-frame vacuum pumps. (Tempest fixed that).So keep it away from that stuff.
 
Ed Haywood said:
Further testing and inspection confirmed the leak is from the oil pressure regulator. The dipstick tube was fine all along.
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Ugh. Chasing small oil leaks is a PITA. Glad you found the offending component. Oil goes everywhere in the engine compartment, and sometimes beyond, when there is a small leak. I've chased down several of these: failed dipstick tube gasket, hardened pushrod seals, faulty mating surface and torque on the crush gasket for the oil sump screen drain plug, cracked or leaking valve cover drain tubes, etc.
 
Jim K said:
The shop that works on my plane buys the stuff in 275 gallon ibc totes. Pretty much the first step in any service they do is wash the engine. I think airplane mechanics don't like to get greasy.
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Airplane mechanics don't like grime to get into places it shouldn't, like cylinders and oil sumps. They also don't like tools slipping, and they like to be able to visually detect leaks, cracks, loose hardware, deteriorating rubber, abraded wire insulation, etc.

I wash down the engine before working on a car too. But that engine cost $5K instead of $50K, so I'm OK using a can of Gunk and a garden hose.
 
Ed Haywood said:
Airplane mechanics don't like grime to get into places it shouldn't, like cylinders and oil sumps. They also don't like tools slipping, and they like to be able to visually detect leaks, cracks, loose hardware, deteriorating rubber, abraded wire insulation, etc.
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Yes. But it is also a legal requirement:

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From a Cessna service manual, inspection section:

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"...if needed." Well, it's most often needed, especially if there is ANY oil leakage and there's dust around to stick to the oil.

Cessna also says this:

1754613755790.png
 
Ed Haywood said:
With an engine cleaning gun. Just spray it on gunky areas to wash away.


I prefer it over citrus or phosphate based solvents because it is petroleum based and less corrosive. It also evaporates much faster than water, so you don't have to worry about little pools staying behind in crevices.

Why are you uncomfortable with it?
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I was afraid it would get into places it shouldn't particularly electrical items. Like mags, starter, alternator, etc.
Do you just let it run off onto the nose gear and the ground?
 
Domenick said:
I was afraid it would get into places it shouldn't particularly electrical items. Like mags, starter, alternator, etc.
Do you just let it run off onto the nose gear and the ground?
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As others stated, good to avoid those areas. But they don't get that dirty anyways. I concentrate on crevices where oil and dust combine to form grime, and anywhere I would like to detect leaks. Flanges, cylinder bases, hose fittings, etc.

Engine guns don't put out a high volume of fluid, more like a mist, and it evaporates quickly, so there's little mess or runoff.

Pretty standard stuff for any maintenance shop.
 
Domenick said:
Do you just let it run off onto the nose gear and the ground?
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There are some specialized drain pans out there designed to catch liquids especially where the local laws prevent any run off. I think AS has them. I usually made my own out of recycled material depending on aircraft. As to the protecting areas on the engine I usually bagged the vac pump and if needed covered other areas with plastic to remind me not to spray there. But never really had any issues.
 
Fixed it! No more leak.

The crush gasket on the oil pressure regulator was completely flat. Easy to see how it happened. Whoever installed it didn't check the thread pitch. They just assumed it was the same as the oil suction plug, which is 20 TPI and should be tightened 135 degrees from finger tight. But the regulator thread is 12 TPI and should only be rotated 90 degrees.
 
Argggh, leak on oil pressure regulator is back!

I did a longer flight. Small leak. I tightened it a few degrees and rewired it. Bigger leak. :mad:

I've got one more crush gasket. Anyone know any tricks?
 
Dummy here, but have you considered the pressure adjusting bolt threads?

Not sure how you would address that, but maybe there is an O ring inside there someplace?
 
A bit of YouTube browsing turned up a guy saying the proper torque is 300 inch pounds, per the Lycoming overhaul manual.

I am following the table of standard torques, which specifies 90 degrees past hand tight for crush gaskets with that TPI.

Guess I gotta research further.
 
Dug into the Lycoming Service Table of Limits and Torque Values.

It is 300 In-lb .... NOT the standard torque for crush washers. That explains it.

No wonder that crush gasket was pancaked. It is supposed to be.
 
Ed Haywood said:
Dug into the Lycoming Service Table of Limits and Torque Values.

It is 300 In-lb .... NOT the standard torque for crush washers. That explains it.

No wonder that crush gasket was pancaked. It is supposed to be.
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Otherwise known as 25 ft-lb, a little less than for a spark plug.
 
Ed Haywood said:
Dug into the Lycoming Service Table of Limits and Torque Values.

It is 300 In-lb .... NOT the standard torque for crush washers. That explains it.

No wonder that crush gasket was pancaked. It is supposed to be.
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I missed that when I posted the crush gasket specs.

The crazy thing here is that there is no oil pressure against that gasket. The regulator is nothing more than a spring that holds a ball against a seat around a hole that leads to the oil gallery, which IS under pressure. When the pressure reaches the setting, the ball lifts off and dumps the excess oil into that regulator cavity, which is drained to the crankcase; therefore, that cavity is not pressurized and leakage should be nonexistent, pretty much. I wonder if the drain hole is obstructed some. Is the oil pressure normal and consistent?

I have used teflon sealant (goop, NOT tape) on those gaskets if they want to seep oil. Just a bit. Any more than a bit just makes a mess and gets into where it should not be.

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Dan Thomas said:
I missed that when I posted the crush gasket specs.

The crazy thing here is that there is no oil pressure against that gasket. The regulator is nothing more than a spring that holds a ball against a seat around a hole that leads to the oil gallery, which IS under pressure. When the pressure reaches the setting, the ball lifts off and dumps the excess oil into that regulator cavity, which is drained to the crankcase; therefore, that cavity is not pressurized and leakage should be nonexistent, pretty much. I wonder if the drain hole is obstructed some. Is the oil pressure normal and consistent?

I have used teflon sealant (goop, NOT tape) on those gaskets if they want to seep oil. Just a bit. Any more than a bit just makes a mess and gets into where it should not be.
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Found a problem with the case surface. I sent you a pic.
 
I think I really fixed it this time. The engine case had a casting defect, or somebody whacked it with a tool. I spent some time with honing stones cleaning up the gasket bearing surface. Just flew it for 30 minutes, no sign of a leak.

Man, what a PITA. But I got a LOT of practice safety wiring.
 
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