Orval Fairbairn wrote:
In article ,
Ross wrote:

Mike Spera wrote:
I have owned this Cherokee 140 since 1994. I have logged over 1000 hours
in it through the original and the now installed overhauled engine. Oil
temps were usually at 180 degrees (both engines)when OATs were between
50-80 degrees or so. It would read 1 needle mark higher when it got to
be 95+ outside. In the last 150 hours or so, it has been drifting up and
is now reading about 2 needle marks above 180 degrees (200 degrees or
so?). I replaced the oil cooler because of age. It was cheaper to
replace it with a new PMA'd unit than to have it checked/cleaned. I
swapped the Vernatherm. No difference. Do the gauges/senders drift off
with age. I am going to test the sender/gauge with hot water and a
thermometer.

Once it gets to that mark, it seems to stabilize.

Baffles are all in good shape.

What else causes temps to drift high? I know that shifting main bearings
can cause this, but I doubt the engine would continue to operate for
this long if this were the case. I do wonder though because the cold oil
pressure is right at redline on takeoff. After 5 minutes it goes back
down into the middle of the green.

Thoughts/theories?

Thanks,
Mike
My oil temp always read low and I took the aircraft temp gage probe and
a multimeter that I had that had a temp probe and heated a small tin can
of oil to 180F, put both probes in the oil, and then marked the aircraft
gage so I would know exactly where 180F was. The O-360 oil was reading
lower than 180 always.

Are the baffle seals in good condition, and curved forward when the cowl
is in place? Also, check the intercylinder baffles, to make sure that
they are properly installed. Any discrepancies in those areas will cause
the cooling air to bypass the cylinders and lead to higher temperatures.

Most production planes have very inefficient cooling, anyhow.


Not sure if you are responding to the OP or me, but my temperatures
(when I had the plane) were always low. And, yes the baffling was
correct. I am sure there were some "leaky" places.

--

Regards, Ross
C-172F 180HP
Sold
KSWI