Oil leak on top of the engine

It seems to be the season for finding oil leaks.

At our completely uneventful annual (just finished two days ago) I asked my
shop to investigate a new leak that I had detected when I de-cowled the
engine for the inspection. All across the top of our 3-year-old, 500-hour
engine, down the seam where the case halves join together, right where the
push rods attach to the case, was a puddle of fresh, clean oil -- enough to
look like I had just spilled some while adding oil...

Trouble was, I HADN'T added any oil recently. With our new air/oil
separator, I no longer need to add oil between oil changes, so it had been
some 24 flight hours since I had last added oil.

With no obvious source of the leak, my mechanic thoroughly cleaned the
engine and resolved to fly it to see where the oil was coming from. The
flying weather wouldn't cooperate until today, but this morning we flew the
plane on its post-annual test flight, found a squawk or two, and returned to
the shop to fix these and check for the source of the leak.

The total flight time was only 0.7 hours, yet the top of the engine once
again looked like I had spilled oil while filling. It was right along the
case halves seam, so with no other apparent source my mechanic figured the
first place to start was to check the torque on the case bolts.

He reached for the first one, and we were both astounded when he was able to
tighten it -- by hand! One by one, all of the case nuts were found to be
very loose (although that was the only one that was hand-tight), and needed
to be re-torqued to 190 inch pounds of torque.

After tightening those, he checked the prop governor housing, and found
those bolts to be way loose, too. Essentially the whole top of the engine
was loose, and oil was leaking at the seam.

After re-torquing everything to spec, I test flew the plane for another 0.5
hours, and was happy to see everything bone dry once again.

Questions:

1. Is this something one should expect after 500 hours of shaking and
rattling? Do these bolts just plain loosen over time, going from hot to
cold hundreds of times?

2. Do you guys re-torque these bolts on a schedule?

3. Is this something your A&P checks at every annual? My guys were clearly
surprised to find these bolts so loose -- and they are the guys who rebuilt
the engine.

4. Are there any other bolts -- say, on the BOTTOM of the engine -- that I
should check for looseness? I looked but couldn't see any.

5. Should I apply LocTite to these bolts?

I suspect I'll be checking those bolts regularly from now on!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

DAMN!

No, that's absolutely not normal. Poor workmanship at the rebuilder.

There are bolts that should have been retorqued at a certain hour.
The shop would have specified which ones.

I really don't know of anyone who makes it a habit to check the torque
on all the engine bolts at each annual. Things like exhaust studs
hardware and intake bolts are checked.

Understand this. If the case is fretting, as it does when bolts are
loose, it's a very serious situation. If this were my engine, I would
have another mechanic check the torque of the through bolts. If
they're off you need to clean it up very well and run it for about
another 1/2 hour on the ground. Do Not Fly This Airplane. If wet,
the engine needs to be pulled and the disassembled, cases sent out and
reassembled. It'll give you something to talk about, anyway.

Don't take my word for it, contact a real engine house for advice and
let the world know if I'm wrong.

I seem to remember being strongly criticized after saying something
about soliciting recommendations for a shop via the newsgroups when
you did it a few years back.


On Thu, 10 Feb 2005 21:25:10 GMT, "Jay Honeck"
wrote:

It seems to be the season for finding oil leaks.

At our completely uneventful annual (just finished two days ago) I asked my
shop to investigate a new leak that I had detected when I de-cowled the
engine for the inspection. All across the top of our 3-year-old, 500-hour
engine, down the seam where the case halves join together, right where the
push rods attach to the case, was a puddle of fresh, clean oil -- enough to
look like I had just spilled some while adding oil...

Trouble was, I HADN'T added any oil recently. With our new air/oil
separator, I no longer need to add oil between oil changes, so it had been
some 24 flight hours since I had last added oil.

With no obvious source of the leak, my mechanic thoroughly cleaned the
engine and resolved to fly it to see where the oil was coming from. The
flying weather wouldn't cooperate until today, but this morning we flew the
plane on its post-annual test flight, found a squawk or two, and returned to
the shop to fix these and check for the source of the leak.

The total flight time was only 0.7 hours, yet the top of the engine once
again looked like I had spilled oil while filling. It was right along the
case halves seam, so with no other apparent source my mechanic figured the
first place to start was to check the torque on the case bolts.

He reached for the first one, and we were both astounded when he was able to
tighten it -- by hand! One by one, all of the case nuts were found to be
very loose (although that was the only one that was hand-tight), and needed
to be re-torqued to 190 inch pounds of torque.

After tightening those, he checked the prop governor housing, and found
those bolts to be way loose, too. Essentially the whole top of the engine
was loose, and oil was leaking at the seam.

After re-torquing everything to spec, I test flew the plane for another 0.5
hours, and was happy to see everything bone dry once again.

Questions:

1. Is this something one should expect after 500 hours of shaking and
rattling? Do these bolts just plain loosen over time, going from hot to
cold hundreds of times?

2. Do you guys re-torque these bolts on a schedule?

3. Is this something your A&P checks at every annual? My guys were clearly
surprised to find these bolts so loose -- and they are the guys who rebuilt
the engine.

4. Are there any other bolts -- say, on the BOTTOM of the engine -- that I
should check for looseness? I looked but couldn't see any.

5. Should I apply LocTite to these bolts?

I suspect I'll be checking those bolts regularly from now on!

"Jon A." wrote:

I really don't know of anyone who makes it a habit to check the torque
on all the engine bolts at each annual. Things like exhaust studs
hardware and intake bolts are checked.

The case bolts on my previous Continental IO-520, circa 1987, had white
paint stripes painted on them to indicate whether they had come loose. The
previous owner, a one-time automotive racer, had a colorful name for these
stripes but at the moment I cannot recall it.

--
Peter













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On Thu, 10 Feb 2005 18:51:03 -0500, "Peter R."
wrote:

"Jon A." wrote:

I really don't know of anyone who makes it a habit to check the torque
on all the engine bolts at each annual. Things like exhaust studs
hardware and intake bolts are checked.

The case bolts on my previous Continental IO-520, circa 1987, had white
paint stripes painted on them to indicate whether they had come loose. The
previous owner, a one-time automotive racer, had a colorful name for these
stripes but at the moment I cannot recall it.

You can use a product called "Torque Seal", available from Spruce for
this. All of your fuel connections should be done. Doesn't actually
seal the torque, but shows you if something has moved.

"Jon A." wrote:

You can use a product called "Torque Seal", available from Spruce for
this. All of your fuel connections should be done. Doesn't actually
seal the torque, but shows you if something has moved.

I think I now recall the name the previous owner called those paint
stripes. "Sabotage spotter."

--
Peter













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There are bolts that should have been retorqued at a certain hour.
The shop would have specified which ones.

No one I've talked to has heard of this schedule with regard to the case
bolts. Have you got a Lycoming reference for this?

Understand this. If the case is fretting, as it does when bolts are
loose, it's a very serious situation. If this were my engine, I would
have another mechanic check the torque of the through bolts.

What are the "through bolts"? Are these the bolts I'm talking about, or
different ones?

Do Not Fly This Airplane.

Too late. We torqued everything to spec, and flew it uneventfully for half
an hour, at all throttle settings, at altitudes up to 4000 feet. No leakage
noted, all six bars on the JPI engine analyzer looked fine, everything
sounded and ran perfectly.

If wet,
the engine needs to be pulled and the disassembled, cases sent out and
reassembled.

What do you mean by "if wet"?

Thanks,
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Fri, 11 Feb 2005 03:30:22 GMT, "Jay Honeck"
wrote:

There are bolts that should have been retorqued at a certain hour.
The shop would have specified which ones.

No one I've talked to has heard of this schedule with regard to the case
bolts. Have you got a Lycoming reference for this?

No, your rebuilder should have it. May be 10 hours or so.

Understand this. If the case is fretting, as it does when bolts are
loose, it's a very serious situation. If this were my engine, I would
have another mechanic check the torque of the through bolts.

What are the "through bolts"? Are these the bolts I'm talking about, or
different ones?

I think you're speaking of the case bolts. The through bolts go all
the way through the case near the cylinder bases. If the case bolts
weren't done properly, there's no reason to believe the through bolts
were, either.

Do Not Fly This Airplane.
Too late. We torqued everything to spec, and flew it uneventfully for half
an hour, at all throttle settings, at altitudes up to 4000 feet. No leakage
noted, all six bars on the JPI engine analyzer looked fine, everything
sounded and ran perfectly.

You'll not see anything special on the engine analyzer. Ask if they
retorqued the cylinders and through bolts. Not a hard job, but very
time consuming removing all the junk around the engine.

If wet,
the engine needs to be pulled and the disassembled, cases sent out and
reassembled.

What do you mean by "if wet"?

Signs of further leakage.

Thanks,

Stay safe, I may need a room one day!

Too late. We torqued everything to spec, and flew it uneventfully for
half
an hour, at all throttle settings, at altitudes up to 4000 feet. No
leakage
noted, all six bars on the JPI engine analyzer looked fine, everything
sounded and ran perfectly.


The point I'm trying to make is it appears that some bolts being torqued
have been overlooked and what is the chance that the cylinder nuts & thru
bolts had been overlooked also?

Simply, You don't know until you check. It'll require 10 minutes if you
have easy access to the engine.

Cylinders may run for a while but can start working on the crankcase, break
one stud then the others follow in quick succession then the cylinder
departs the engine.
Some instances it may appear that the connecting rod broke first to cause
the damage, but actually the cylinder left first and the rod broke after.

I don't have the link handy, but Sacramento Sky Ranch website has a bunch
of information.

Good chance that is just the spine bolts and you'll make TBO.

Take care

Kent Felkins

The point I'm trying to make is it appears that some bolts being torqued
have been overlooked and what is the chance that the cylinder nuts & thru
bolts had been overlooked also?

Simply, You don't know until you check. It'll require 10 minutes if you
have easy access to the engine.

I'm having my shop check these this morning.

To those who think that the bolt might have been loose from the start,
remember: I watched the shop build this engine, and I personally saw them
check the torque on the engine case bolts. They *were* tightened to spec.

I also know that they never re-checked them, however, and my main mechanic
has admitted that they never check these as a matter of course.

In the case of the O-540, anyway, the case bolts are torqued surprisingly
low, and they are not secured in any way. No cotter pin, no safety wire, no
LocTite, no lock washer -- NOTHING prevents those nuts/bolts from loosening
over time. It seems like a ridiculous over-sight, but that's the way it
is.

A guy on the Cherokee Chat actually had a case bolt FALL OUT after loosening
over time from vibration, so this is not an unheard-of problem. I'm
surprised it's never been addressed in this forum before -- at least not in
my 7 years here.

I've bought a torque wrench, and I'm going to be checking ALL of these bolts
every time I change the oil, from now on.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" wrote in message
news:6q3Pd.63958$eT5.59714@attbi_s51...
I've bought a torque wrench, and I'm going to be checking ALL of these
bolts
every time I change the oil, from now on.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"


You may want to check with your mechanic about this also. I think the proper
way to check torque of a bolt is to loosen it first and then re-torque.
This could lead to case-cracks after multiple sessions. The best method of
checking might be the "tamper stripe". Have your mechanic apply it after
torque and then just examine it at oil change.

Allen