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

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

"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, 7:39 am, "Dan Luke" wrote:
"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?


Did you get any compression numbers from the shop? I've found that
what TCM considers to be "OK" compressions, wouldn't necessarily be
considered OK by a lot of mechanics. A friend had a cylinder in the
50s a couple of years after a TCM factory overhaul and they considered
it "OK".

John Galban=====N4BQ (PA28-180)

"John Galban" wrote:


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


Did you get any compression numbers from the shop? I've found that
what TCM considers to be "OK" compressions, wouldn't necessarily be
considered OK by a lot of mechanics. A friend had a cylinder in the
50s a couple of years after a TCM factory overhaul and they considered
it "OK".


Compressions were all in the 74-78 range, about the same as at annual a few
months before.

--
Dan
T-182T at BFM