Dirty oil, part II

Back in January, I posted my concern about the oil in my 172RG (Lyc. O-360)
turning black just two or three hours after being changed. My regular
mechanic said no to worry, the crud probably came from oil that didn't get
drained from the oil cooler and associated plumbing.

Still concerned, I took the bird to Teledyne Continental's shop across the
Bay in Fairhope for an evaluation of the engine. They reported that
compressions were good, crankcase pressure was ok and borescope examinations
revealed nothing unusual in the cylinders. Relieved, I concluded that my
mechanic was probably right. I resolved not to worry about it.

Now I've got another airplane with an engine (Lyc. TIO-540) that is very
similar, at least in its cylinders and bottom end. I had the oil and filter
changed as soon as I got it because the oil was black. 15 hours later, the
oil is just barely showing enough contamination to make the dipstick easy to
read.

So now I'm wondering: what was really going on in the first airplane's
engine? What could have been getting the oil dirty so quickly yet not show
up in the TC shop's examination?

--
Dan
T-182T at BFM

From Sac Sky Ranch:
1. Blowby of combustion gases past the piston ring belt. Accompanied by high
oil temperature and increased oil flow out engine breather. Check engine
compression.

2. Excessive oil temperatures. (any carbon deposits in the screen or
filter?)


3. Contamination of oil.

Jim



"Dan Luke" wrote in message
...
Back in January, I posted my concern about the oil in my 172RG (Lyc.
O-360)
turning black just two or three hours after being changed. My regular
mechanic said no to worry, the crud probably came from oil that didn't get
drained from the oil cooler and associated plumbing.

Still concerned, I took the bird to Teledyne Continental's shop across the
Bay in Fairhope for an evaluation of the engine. They reported that
compressions were good, crankcase pressure was ok and borescope
examinations
revealed nothing unusual in the cylinders. Relieved, I concluded that my
mechanic was probably right. I resolved not to worry about it.

Now I've got another airplane with an engine (Lyc. TIO-540) that is very
similar, at least in its cylinders and bottom end. I had the oil and
filter
changed as soon as I got it because the oil was black. 15 hours later,
the
oil is just barely showing enough contamination to make the dipstick easy
to
read.

So now I'm wondering: what was really going on in the first airplane's
engine? What could have been getting the oil dirty so quickly yet not
show
up in the TC shop's examination?

--
Dan
T-182T at BFM

"Jim Burns" wrote:

From Sac Sky Ranch:
1. Blowby of combustion gases past the piston ring belt. Accompanied by
high
oil temperature and increased oil flow out engine breather. Check engine
compression.

Borescopes and compressions were ok, but I still think it was something like
this that was going undetected. But what?


oil temperatures. (any carbon deposits in the screen or
filter?)

Oil temp. was monitored on the JPI engine analyzer with a high alarm setting
of 215 deg. F. Never had an alarm.



3. Contamination of oil.

That's what my regular mechanic said.

--
Dan
T-182T at BFM

As an aside IO540... our Aztec engines run hot. With the Piper oil temp
probe located just after the cooler and the JPI probe located ahead of the
#1 cylinder, the Piper oil temp rarely hit 200 but the JPI's will show 230
and if we climb out too steeply they'll bust the 235 alarm. I changed the
oil and filters in ours last night and noted about 1/2 dozen carbon
particles in the sump screens of each engine with a few small chunks in the
filters. 66 hours on filter changes. Oil had 33 hours on it and was brown,
definitely not black.
Jim

"Dan Luke" wrote in message
...

"Jim Burns" wrote:

From Sac Sky Ranch:
1. Blowby of combustion gases past the piston ring belt. Accompanied by
high
oil temperature and increased oil flow out engine breather. Check engine
compression.

Borescopes and compressions were ok, but I still think it was something
like
this that was going undetected. But what?


oil temperatures. (any carbon deposits in the screen or
filter?)

Oil temp. was monitored on the JPI engine analyzer with a high alarm
setting
of 215 deg. F. Never had an alarm.



3. Contamination of oil.

That's what my regular mechanic said.

--
Dan
T-182T at BFM

"Dan Luke" wrote in message
...

"Jim Burns" wrote:

From Sac Sky Ranch:
1. Blowby of combustion gases past the piston ring belt. Accompanied by
high
oil temperature and increased oil flow out engine breather. Check engine
compression.

Borescopes and compressions were ok, but I still think it was something
like this that was going undetected. But what?


oil temperatures. (any carbon deposits in the screen or
filter?)

Oil temp. was monitored on the JPI engine analyzer with a high alarm
setting of 215 deg. F. Never had an alarm.



3. Contamination of oil.

That's what my regular mechanic said.

--
Dan
T-182T at BFM

Lets see 2 or 3 Compression Rings? is the Oilier (2 Scrapers And An
Expander) above or below the wrist pin? If it is above the wristpin
depending on piston design the 2nd or 3rd lower compression ring land is
probably slightly bent or tollerances to tight and binding the oilier witch
will not show on a leak down test but will cause lots of blow-by and or heat
when operating at a higher rpm. many other things are possible.

On Jul 13, 9:11 am, "Jim Burns" wrote:
As an aside IO540... our Aztec engines run hot. With the Piper oil temp
probe located just after the cooler and the JPI probe located ahead of the
#1 cylinder, the Piper oil temp rarely hit 200 but the JPI's will show 230
and if we climb out too steeply they'll bust the 235 alarm. I changed the
oil and filters in ours last night and noted about 1/2 dozen carbon
particles in the sump screens of each engine with a few small chunks in the
filters. 66 hours on filter changes. Oil had 33 hours on it and was brown,
definitely not black.
Jim

"Dan Luke" wrote in message

...





"Jim Burns" wrote:

From Sac Sky Ranch:
1. Blowby of combustion gases past the piston ring belt. Accompanied by
high
oil temperature and increased oil flow out engine breather. Check engine
compression.

Borescopes and compressions were ok, but I still think it was something
like
this that was going undetected. But what?

oil temperatures. (any carbon deposits in the screen or
filter?)

Oil temp. was monitored on the JPI engine analyzer with a high alarm
setting
of 215 deg. F. Never had an alarm.

3. Contamination of oil.

That's what my regular mechanic said.

--
Dan
T-182T at BFM- Hide quoted text -

- Show quoted text -

I have never understood why the manufacturer would plumb the oil temp
sender after the cooler, it gives a false reading. If the cooler was
very efficient it could shed 50+ degrees. So lets say the after cooler
temp was 220 degrees after a long climb out during hot weather, that
would mean the actual oil temp in the pan of the motor was 270+. Funny
the FAA lets the certified planes get away with it plumbed that way.

wrote:

I have never understood why the manufacturer would plumb the oil temp
sender after the cooler, it gives a false reading. If the cooler was
very efficient it could shed 50+ degrees. So lets say the after cooler
temp was 220 degrees after a long climb out during hot weather, that
would mean the actual oil temp in the pan of the motor was 270+. Funny
the FAA lets the certified planes get away with it plumbed that way.


Thats how it is in our Mazda's... we measure the coolant temp before the
rad, but the oil temp AFTER the cooler.

What makes you think someone is "getting away" with something?

Dave

Dave S wrote:
wrote:

I have never understood why the manufacturer would plumb the oil temp
sender after the cooler, it gives a false reading. If the cooler was
very efficient it could shed 50+ degrees. So lets say the after cooler
temp was 220 degrees after a long climb out during hot weather, that
would mean the actual oil temp in the pan of the motor was 270+. Funny
the FAA lets the certified planes get away with it plumbed that way.


Thats how it is in our Mazda's... we measure the coolant temp before the
rad, but the oil temp AFTER the cooler.

What makes you think someone is "getting away" with something?

Dave

Let me rephrase my reply a bit..

Oil flow is from the pan, to the pump, to the cooler, to the engine. The
temp going IN to the engine is what counts, from a viscosity and cooling
standpoint. The temp in the pan is NOT reflective of the temp going INTO
the engine.

On Jul 13, 7:08 pm, Dave S wrote:
Dave S wrote:
wrote:

I have never understood why the manufacturer would plumb the oil temp
sender after the cooler, it gives a false reading. If the cooler was
very efficient it could shed 50+ degrees. So lets say the after cooler
temp was 220 degrees after a long climb out during hot weather, that
would mean the actual oil temp in the pan of the motor was 270+. Funny
the FAA lets the certified planes get away with it plumbed that way.

Thats how it is in our Mazda's... we measure the coolant temp before the
rad, but the oil temp AFTER the cooler.

What makes you think someone is "getting away" with something?

Dave

Let me rephrase my reply a bit..

Oil flow is from the pan, to the pump, to the cooler, to the engine. The
temp going IN to the engine is what counts, from a viscosity and cooling
standpoint. The temp in the pan is NOT reflective of the temp going INTO
the engine.- Hide quoted text -

- Show quoted text -

The temp in the pan is true state of affairs in the engine. Hell, I
could plumb several oil coolers in series and dissapate most of the
heat, install the oil temp probe just before the cool oil re-enters
the motor and tell everyone my my oil temp only runs 110 degrees, of
course that would be smoke and mirrors and only fools would buy it. My
point was and is, if someone wants to really know how hard a motor is
working use the true heat numbers it is creating. not the altered
numbers. By going with your concept,why don't we use the temp of the
coolant coming back from the radiator instead of the true temp as is
passes through the thermostat housing on the way to the radiatior?

Ben
www.haaspowerair.com

wrote in message
ps.com...
The temp in the pan is true state of affairs in the engine.

While that might be true, I think the benefit of measuring oil temperature
as the oil enters the engine is that it enables the engine manufacturer to
provide meaningful oil temperature specifications. For my engine, TCM says
that the oil entering the engine (after passing through the oil cooler) can
be as hot as 240°F at full power and still be acceptable. TCM apparently
feels that so long as the oil entering the engine is no hotter than that,
then the engine will be fine so long as I'm using a recommended oil. For
takeoff, the oil entering the engine should be at least 100°F as it enters
the engine.

If we measured oil pan temperatures, the engine manufacturer would never
know what kind of oil cooler we had or how well the cooler was installed and
could not specify a maximum or minimum oil temperature because they wouldn't
know how efficient the oil cooler was.

Dennis