Jim, all the indicators point to severe high oil temperature. I'll bet that
if you continue to run high power in climb or cruise, to the extent that the
oil pressure dips just below the 60 PSI mark, you also begin to experience
prop overspeeding beyond the set RPM.

Do you have anything like a JPI engine analyzer, to which you can add an oil
temperature sensor? They usually mount in the right front oil gallery on
the Lycomings. I would bet a dollar to a doughnut that you are experiencing
oil temperatures in the 260 to 270 degrees F range (130 C). 200 C (390 F)
on the CHT is also significantly higher than these engines should run in
cruise; another indication of excessive oil temperatures. Cruise CHT should
be closer to 325 F (162 C). You need to get this sorted out soon, or limit
your climbs and cruise to power settings that result in more normal
temperatures. Normal oil temp for most of our applications is closer to 190
F in cruise (88C). This is right about where the little white dot is, in
the green on the oil temp gauge.

You probably won't be able to load the engine enough to reproduce this
problem on the ground. It usually takes a long hot climb, along with ten to
twenty minutes at high-power cruise, to make it show up.

I know you said that the Vernatherm was replaced last year. Are you 100%
certain it was replaced with a brand-new part, as opposed to a
used-serviceable part? Used Vernatherms should never be reinstalled; they
have a very high failure rate if the Lycoming test is performed on them. I
remain suspicious of either the valve or its mating seat. One member
reported going through three rounds of valve and seat repair, before it got
fixed. Another possibility is a partially clogged oil cooler. Southwest
Cooler Service in Dallas, TX does good work, but you can probably find a
closer service. Do NOT let a local technician try to flush it locally with
solvent; that will not clean clogged passages, and is a waste of money.

Sometimes the remote cooler setups result in relocation of the Vernatherm
from its stock location. In turn, this usually provides the valve with a
new seat. If you are certain that you got a brand new, good valve, and that
it has been properly installed in a new adapter housing, and that correct
gaskets were properly installed, you might want to start with the cooler
flush. Particularly if there are no records showing that it has ever been
done. It should always be done at overhaul, or whenever work is done due to
contaminants having been found in the oil filter media (or screen)
examination, but the coolers are very often neglected.


From: musketeermail@yahoogroups.com [mailto:musketeermail@yahoogroups.com]
On Behalf Of Jim Campbell
Sent: Sunday, February 12, 2006 8:57 AM
To: musketeermail@yahoogroups.com
Subject: [musketeermail] Re: Too much oil pressure?

Very many thanks for the link to that article, Bob.
I have been suffering from what I believe to be low oil pressure/high
temperature. I had a spin-on, firewall-mounted kit installed because
of claims that it assisted with lowering oil temperatures but it made
no difference.
At this time of the year oat is 28C at 1500msl and the oil pressure at
cruise shows neatly on the edge of the yellow segment with temp almost
into the red. CHT is 200C. (at 2600/26mp ~13gph)
Had the vernatherm replaced last year too.
Of course, I notice it more when the oil and filter have been changed
- like last week!
Is there a way to raise the maximum oil pressure? Or should I just fly
higher, or slower?
Jim C

--- In musketeermail@yahoogroups.com, Bob Steward <n76lima@...> wrote:
> >Had the oil pressure go over the top of the red today... 12 minutes
> >T/O at 3,000'msl, 2500rpms, oil temp unknown due to sender
> >always high. Landed. Oil on dipstick looked thin. Impossible to
> >quantity at high temperature. I did not wait for cooling. Added two
> >to the 5qts (I think) already onboard. Ran cooler on the way back
home at
> >2300rpms.
> >
> >Question: Can you have too much oil pressure?
> Within reason, its like being too rich or too thin. <G>
> The down side to "too much" oil pressure is that if you have a can type
> filter you can blow the gasket out or fail the crimped seal on the
> housing and blow out all the oil in a few seconds. You might also
> the sealant between the case halves if your engine case hasn't been
> modified to provide a separation between the forward and center cam
> journals and the outside of the case.
> Cessna worked with Lycoming to RAISE the oil pressure on the current
> production planes. They changed the red line on the gauge and they
> up the pressure at a different point on the engine where the
pressure is
> known to be less than at the pump outlet, which is where the older
> Lycoming's picked the pressure tap.
> The end result is that if you measured the OP on a new C-172 at the old
> location where your Musketeer is taking its pressure reading, that
the red
> line for the new Cessna is about 125 PSI, or ~25# higher than the older
> plane's gauges read it.
> For those that want a more in depth discussion, I refer you to this
> http://egaa.home.mindspring.com/new.htm
> Bob Steward, A&P IA
> Birmingham, AL

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