Engine... Overhaul? / Replace? advice please

The engine in our 1972 C172 (0-320-E2D) is now due for overhaul after 2800
hours as lead particles have started appearing in the oil filter. (Top
overhaul was at 1500, bottom end untouched). Still running beautifully, no
vibration, plenty of power, good compressions etc.

We are not sure how best to proceed.

Prices shown are in UK pounds and include taxes (vat @ 17.5%)
In addition to the overhaul we need to add another £1300 to have the engine
taken out and put back in again, (includes the engine mount kit and oil).

One option is to have our existing engine overhauled by a local company
(Jade Air / Norvic) who have a pretty good reputation (they did the top
overhaul about 10 years ago). The cost of this will be about £9987

Second option is to use Norvic but go for their "Millenium" rebuild at
£11491 in which "new cylinders are the
Millenium investment cast type and the crankshaft and connecting rods are
rebalanced to a finer tolerance than standard Lycoming limits" whatever that
really means.

Third option is Lycoming factory exchange "overhauled" £11714

Fourth option is Lycoming factory exchange "re-built" £13914

I understand that with "re-built" you get a new log book. This sounds good
but in practice it is because the engine has been re-built from a collection
of untraceable parts, hence the new log book, so the advantage seems
emotional rather than mechanical!

One big question......
As far as we know, there is nothing fundamentally wrong with our engine and
it has a "known" history, no prop strikes or anything nasty. What is the
chance of finding a cracked crankshaft or something equally nasty?
If we have our own engine overhauled (zero timed) is that better than
swapping it for a Lycoming overhauled engine whose history we have no
knowledge of?

I have heard that engines can only be re-worked about three times before
they are out of spec. If we get a Lycoming exchange engine how do we know
that it hasn't already been re-worked two or three times and would be
rejected at the next overhaul?

It is a serious amount of money to find and I just don't have the knowledge
and experience to know what is the best route to take. Instinctively I
rather like the idea of having my own engine overhauled and keeping the
original plane intact, but maybe I am too sentimental!

Over to you for advice please...

Many Thanks

Les

It's always nice to have a factory new engine, and a 0 timed one
should be grand. I wouldn't worry about the untracability of parts as
you can trace them all back to the factory (the manufacturer). That
said, a local shop can almost always give you a better deal when they
rebuild. If this is the first o/h, most parts will be serviceable,
but I'm sure ALL parts will be either checked or sent to the
appropriate shops to be inspected fully. Millennium Cylinders are
great, but I think I would spend an extra few dollars on making sure
the entire engine has been balanced by a shop that specializes in
this. It'll add another 400 or 500 (U.S.) to the price, but will
really make a difference in smoothness and longevity.


On Sat, 14 Feb 2004 11:17:47 -0000, "text news"
wrote:

The engine in our 1972 C172 (0-320-E2D) is now due for overhaul after 2800
hours as lead particles have started appearing in the oil filter. (Top
overhaul was at 1500, bottom end untouched). Still running beautifully, no
vibration, plenty of power, good compressions etc.

We are not sure how best to proceed.

Prices shown are in UK pounds and include taxes (vat @ 17.5%)
In addition to the overhaul we need to add another £1300 to have the engine
taken out and put back in again, (includes the engine mount kit and oil).

One option is to have our existing engine overhauled by a local company
(Jade Air / Norvic) who have a pretty good reputation (they did the top
overhaul about 10 years ago). The cost of this will be about £9987

Second option is to use Norvic but go for their "Millenium" rebuild at
£11491 in which "new cylinders are the
Millenium investment cast type and the crankshaft and connecting rods are
rebalanced to a finer tolerance than standard Lycoming limits" whatever that
really means.

Third option is Lycoming factory exchange "overhauled" £11714

Fourth option is Lycoming factory exchange "re-built" £13914

I understand that with "re-built" you get a new log book. This sounds good
but in practice it is because the engine has been re-built from a collection
of untraceable parts, hence the new log book, so the advantage seems
emotional rather than mechanical!

One big question......
As far as we know, there is nothing fundamentally wrong with our engine and
it has a "known" history, no prop strikes or anything nasty. What is the
chance of finding a cracked crankshaft or something equally nasty?
If we have our own engine overhauled (zero timed) is that better than
swapping it for a Lycoming overhauled engine whose history we have no
knowledge of?

I have heard that engines can only be re-worked about three times before
they are out of spec. If we get a Lycoming exchange engine how do we know
that it hasn't already been re-worked two or three times and would be
rejected at the next overhaul?

It is a serious amount of money to find and I just don't have the knowledge
and experience to know what is the best route to take. Instinctively I
rather like the idea of having my own engine overhauled and keeping the
original plane intact, but maybe I am too sentimental!

Over to you for advice please...

Many Thanks

Les

text news wrote:

Second option is to use Norvic but go for their "Millenium" rebuild at
£11491 in which "new cylinders are the
Millenium investment cast type and the crankshaft and connecting rods are
rebalanced to a finer tolerance than standard Lycoming limits" whatever that
really means.

Most companies use a technique called "sand casting" to make the cylinder blanks.
Millenium uses "lost wax" casting, AKA "investment" casting. The lost wax technique
captures finer details and will allow greater precision. You will be able to see
this in the cooling fins. There are also claims that investment casting produces
a better quality metal with less tendency to have embedded stress points. It is
certainly possible to accomplish this, since one can use higher pressures when
forcing the metal into the mold. "Rebalancing to a finer tolerance" simply means
that they try to make the counterweights on the crankshaft match the pistons. If
they do a better job of this than Lycoming does, the engine will vibrate less.


I understand that with "re-built" you get a new log book. This sounds good
but in practice it is because the engine has been re-built from a collection
of untraceable parts, hence the new log book, so the advantage seems
emotional rather than mechanical!

You've been lied to. When Lycoming creates a remanufactured engine, they use mainly
new parts. Whether new or used, all parts used meet the spcifications for new parts.
That's the logic behind the new logbook.

When Lycoming overhauls an engine, they also use used parts "from a collection of
untraceable parts", but those parts only have to meet the specifications for return
to service. Either way, they install new pistons and cylinders.

One big question......
As far as we know, there is nothing fundamentally wrong with our engine and
it has a "known" history, no prop strikes or anything nasty. What is the
chance of finding a cracked crankshaft or something equally nasty?

There's an excellent chance that the crankshaft will be pitted, possibly badly
enough to require replacement with a solid crank. It's highly unlikely that it
would be cracked. The camshaft is more likely to require replacement.

If we have our own engine overhauled (zero timed) is that better than
swapping it for a Lycoming overhauled engine whose history we have no
knowledge of?

The main thing that gives problems is the cylinders. In a field overhaul, your
old cylinders are usually bored and re-used. If necessary, the bore may be
plated back up to size. Other things may be done to recondition them, but, any
way you look at it, they've put up with a lot of abuse. Few cylinders will reach
TBO three times; some won't make it twice. Lycoming replaces the cylinders with
new.

I have heard that engines can only be re-worked about three times before
they are out of spec. If we get a Lycoming exchange engine how do we know
that it hasn't already been re-worked two or three times and would be
rejected at the next overhaul?

As far as the "bottom end" is concerned, you don't.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.

text news wrote:
snip
: One big question......
: As far as we know, there is nothing fundamentally wrong with our engine and
: it has a "known" history, no prop strikes or anything nasty. What is the
: chance of finding a cracked crankshaft or something equally nasty?
: If we have our own engine overhauled (zero timed) is that better than
: swapping it for a Lycoming overhauled engine whose history we have no
: knowledge of?

The engine in my airplane (O-360-A4A) has been overhauled 3 times, and now
has 6200 hours total on it, 900 since it was overhauled last. It still
has the original crankshaft, crankcase halves, etc., but the cylinders,
camshaft, pistons, etc. have been replaced. If your engine is running well,
and you know its history (as it sounds like you do), there is no reason
not to have it zero-timed. Do investigate what components will be replaced
with new, such as the camshaft which is a known weakness in Lycoming
engines. In general, the more components replaced with new the better.

On an opposite note, some years ago a friend of mine purchased a Warrior
with a worn-out engine. Since he did no know the history of this engine,
he opted for a Lycoming zero-timed engine. Recently he had a serious problem
with this engine. After 6 years and 600 hours, the case developed a crack.
Lycoming took the engine back (out of warranty!), replaced the cracked
case half and all of the wear items inside (bearings, mainly), and returned
the engine. My friend was charged only for shipping. I would doubt that
any other shop would do the same.

: I have heard that engines can only be re-worked about three times before
: they are out of spec. If we get a Lycoming exchange engine how do we know
: that it hasn't already been re-worked two or three times and would be
: rejected at the next overhaul?
You do not know the history of any parts in the exchange engine, unless they
were installed new.

: It is a serious amount of money to find and I just don't have the knowledge
: and experience to know what is the best route to take. Instinctively I
: rather like the idea of having my own engine overhauled and keeping the
: original plane intact, but maybe I am too sentimental!

You might consider a "custom overhaul" by Lycoming, wherein you ship them
your engine, they overhaul it, and ship it back to you. The downside is
that the time required would be longer than exchanging the engine, as you'd
need to ship it to the US, and have it shipped back to the UK.

There are a few websites you might look at:
www.textron.lycoming.com has some information about the terminology used;
www.mattituck.com is a major US-based overhauler of engines;
www.pennyanaero.com is another US-based engine overhauler.

--
Aaron Coolidge (N9376J)

I think I would spend an extra few dollars on making sure
the entire engine has been balanced by a shop that specializes in
this. It'll add another 400 or 500 (U.S.) to the price, but will
really make a difference in smoothness and longevity.

When I was researching my options with our Lycoming O-540, I was told that
balancing a normally aspirated air-cooled engine is a waste of money. The
imbalances in fuel distribution are so great that any improvement in
smoothness the balancing might impart would be obliterated by the normal
"roughness" (relatively speaking) of the engine.

A fuel-injected engine is a different story.

I went with all new Millennium cylinders, and a field overhaul at a trusted
shop. We've been very happy with the results.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Sat, 14 Feb 2004 18:11:50 GMT, "Jay Honeck"
wrote:

I went with all new Millennium cylinders, and a field overhaul at a trusted
shop. We've been very happy with the results.

What benefits did you expect from the Millennium cylinders? (I
understand about the casting methods, but sand-cast Lyc O-540 jugs
have logged many a mile.) What did you do for mags? Why?

(Our engine is about to be torn down and decisions must soon be made.)

Don

text news wrote:

The engine in our 1972 C172 (0-320-E2D) is now due for overhaul.....
If we get a Lycoming exchange engine how do we know
that it hasn't already been re-worked two or three times and would be
rejected at the next overhaul?

Why do you think this is important? This engine lasted 32 years. Do you really
think that you will still own the plane 32 years from now when it needs another
engine?

Even if you do still own it, this will only matter if you do a field overhaul
next time. If you swap for another Lycoming rebuilt, you'll get a different set
of parts (collectively known as an engine) and it won't matter if your old ones
meet the serviceability limits or not.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.

What's the guarantee on the factory exchange?
denny
"G.R. Patterson III" wrote in message
...


text news wrote:

The engine in our 1972 C172 (0-320-E2D) is now due for overhaul.....
If we get a Lycoming exchange engine how do we know
that it hasn't already been re-worked two or three times and would be
rejected at the next overhaul?

Why do you think this is important? This engine lasted 32 years. Do you
really
think that you will still own the plane 32 years from now when it needs
another
engine?

Even if you do still own it, this will only matter if you do a field
overhaul
next time. If you swap for another Lycoming rebuilt, you'll get a
different set
of parts (collectively known as an engine) and it won't matter if your old
ones
meet the serviceability limits or not.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way
that
you look forward to the trip.

Dennis O'Connor wrote:

What's the guarantee on the factory exchange?

Lycoming gives 1 year full warrantee on all their engines. They give a second
year pro-rated warrantee on new and reman engines.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.

text news wrote:

We are not sure how best to proceed.

When I was checking the Lycoming web site for some other info, I ran across a
little item that might help you justify the extra cost of going to them for the
engine. They state that their reman and overhauled engines come with all the
accessories that they usually ship with a new one. I don't know how many items
that would be, but that would at the very least mean that you'd get new magnetos
with the engine. You won't get that with a field overhaul. You might check into
what that involves.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.