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  #21  
Old February 5th 07, 01:13 AM posted to rec.aviation.owning
Michelle P
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Posts: 154
Default dirty oil

Dan Luke wrote:
wrote:


Definitely have an A&P borescope that engine. Broken ring maybe.



Talked to my mechanic this morning. He said not to worry; the dirty oil is
from the oil cooler and its plumbing, which don't get drained when the oil is
changed.


Should I pay to have the cylinders 'scoped?

Not sure I would completely believe this one. less than 1qt in 8 should
not turn the oil black. It will discolor it but it should not be black.
We had the oil in an engine on one of our 337s turn black in a couple of
hours. I talked to my boss (also an A&P) about this and we pulled the
engine and replaced it. Something was definitely wrong.

Michelle
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  #22  
Old February 5th 07, 01:32 AM posted to rec.aviation.owning
stearmandriver
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Posts: 9
Default dirty oil

there are other possibilities also. Have you changed fuel suppliers,
or maybe gone from avgas to mogas or mogas to avgas? Some fuels burn
a bit more slowly than others as a function of just what the actual
octane is. If burning slower, it will create more carbon in the
exhaust, go past the ring gap,then thru the valve guide clearances.
Or, your mixture control could be screwed up, and it's not leaning the
way it did.

In general, it's good to know what the usual behavior of one's engine
is. Black oil soon after change in some engines isn't always evidence
of a problem, I drive an old radial engined beast, and even after
overhaul, with the clearances and low normal compression, the oil is
black in 2 hours, tops. the thing having been designed to run on 70
octane doesn't help, either, with modern hi-octane only. Just thought
I'd mention this in case someone else who has the problem panics
before they find out it's normal for their engine.

Looking in the rocker boxes is a good start, however.

  #23  
Old March 4th 07, 06:45 PM posted to rec.aviation.owning
Stan Prevost
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Posts: 118
Default dirty oil

So, Dan, how did this turn out?


"Dan Luke" wrote in message
...
The oil in my Lyc. O-360 F1A6 is black only two hours after being changed.

What could be causing this? Compressions were in the 70s at annual in
September.

--
Dan
C172RG at BFM



  #24  
Old March 4th 07, 08:18 PM posted to rec.aviation.owning
Dan Luke
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Posts: 678
Default dirty oil


"Stan Prevost" wrote:

So, Dan, how did this turn out?


No unusual deposits under the valve covers.

The airplane is going into Teledyne Continental's shop in Fairhope tomorrow to
have the cylinders scoped. Will advise.

--
Dan
C172RG at BFM


  #25  
Old March 5th 07, 09:33 PM posted to rec.aviation.owning
Dan Luke
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Posts: 678
Default dirty oil

"Stan Prevost" wrote:

So, Dan, how did this turn out?



Friday, I took the airplane to Teledyne Continental's shop in Fairhope, AL
for a "second opinion" on the engine.

Just got the report: the engine seems fine. Compressions are ok, crankcase
pressure is ok, cylinders all looked good when bore-scoped.

This mechanic said the same thing my regular mechanic said about the dirty
oil: it most likely came from the oil cooler and associated plumbing which
doesn't get drained at oil change unless you pull a line off the cooler.

--
Dan
C-172RG at BFM


  #26  
Old March 5th 07, 09:55 PM posted to rec.aviation.owning
Denny
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Posts: 562
Default dirty oil



No one I know breaks the connections and drains the cooler at routine
oil changes...
if the oil is changed before it turns black then the oil cooler will
not have black sludge left in it.. The contained oil will be no
dirtier than what was drained and is diluted by the fresh oil...
Frequent oil changes is the solution...

Now, if you have a pan heater and you are coking your oil with so
called 'preheats' than that residue and char will collect where the
oil flow is the lowest, which is the cooler where the Vernatherm stops
the flow... The cure is to stop using the pan heater...

If you recently changed oil types to one that is more aggressively
detergent which acted as a solvent and loosened the gunk in the
cooler, then this is likely a one time issue... A self curing
situation...

GL .... denny


  #27  
Old March 6th 07, 12:49 AM posted to rec.aviation.owning
Stan Prevost[_1_]
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Posts: 71
Default dirty oil

Thanks for the update, Dan, and glad it is not anything serious. Someone
said that as long as the engine makes full power and doesn't make metal,
don't worry about compressions etc. Presumably that covers black oil too.

Stan


"Dan Luke" wrote in message
...
"Stan Prevost" wrote:

So, Dan, how did this turn out?



Friday, I took the airplane to Teledyne Continental's shop in Fairhope, AL
for a "second opinion" on the engine.

Just got the report: the engine seems fine. Compressions are ok,
crankcase pressure is ok, cylinders all looked good when bore-scoped.

This mechanic said the same thing my regular mechanic said about the dirty
oil: it most likely came from the oil cooler and associated plumbing which
doesn't get drained at oil change unless you pull a line off the cooler.

--
Dan
C-172RG at BFM



  #28  
Old March 6th 07, 05:47 AM posted to rec.aviation.owning
Montblack
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Posts: 972
Default dirty oil

("Denny" wrote)
No one I know breaks the connections and drains the cooler at routine oil
changes...
if the oil is changed before it turns black then the oil cooler will not
have black sludge left in it.. The contained oil will be no dirtier than
what was drained and is diluted by the fresh oil...
Frequent oil changes is the solution...



Doing our (vehicle) oil changes, I drain the old oil. I use a "flush filter"
that goes on next. I add (less expensive oil) and run the car for 20
minutes - while I clean up from the first batch.

On my second oil change, the "flush filter" gets drained and returned to its
(labeled) box on the shelf. A fresh filter is used, then I add my good oil
and I'm all set.

When I do it this way in my cars, the oil stays golden (like new) for 3,000
miles. If I do it the normal way, my drain oil looks like ...drain oil,
after 3,000 miles.

Does anyone do this with their planes - an oil flush, then a change?

For our cars, it adds about $5 to a driveway oil change. I buy a new "flush
filter" every year.


Montblack-gold


  #29  
Old March 6th 07, 06:02 AM posted to rec.aviation.owning
Bob Noel
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Posts: 1,374
Default dirty oil

In article ,
"Montblack" wrote:

Does anyone do this with their planes - an oil flush, then a change?


I don't.

--
Bob Noel
Looking for a sig the
lawyers will hate

  #30  
Old March 6th 07, 07:56 AM posted to rec.aviation.owning
Roger[_4_]
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Posts: 677
Default dirty oil

On 5 Mar 2007 12:55:43 -0800, "Denny" wrote:



No one I know breaks the connections and drains the cooler at routine
oil changes...
if the oil is changed before it turns black then the oil cooler will
not have black sludge left in it.. The contained oil will be no
dirtier than what was drained and is diluted by the fresh oil...
Frequent oil changes is the solution...


Lordy,
I don't even have a filter and the oil is black when I change it at 25
hours. However it takes it 15 to 20 hours before the new oil darkens
much.

Now, if you have a pan heater and you are coking your oil with so
called 'preheats' than that residue and char will collect where the
oil flow is the lowest, which is the cooler where the Vernatherm stops
the flow... The cure is to stop using the pan heater...


I use the Tanis which is temperature controlled or rather limited.
It'll peak at somewhat under 50C. Hot enough if you just stick your
hand in there you will jump back, but cool enough that when you expect
it you can put your hand on the pan or cylinder heads and leave it
there.

Dipstick sump heaters are notorious for coking up.


If you recently changed oil types to one that is more aggressively
detergent which acted as a solvent and loosened the gunk in the
cooler, then this is likely a one time issue... A self curing
situation...


Remember the old cars that got a dose of detergent oil after years of
non detergent?


GL .... denny

73

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
 




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