Cool Oil Temperatures

[Ross and Paula Richardson]

I own a '65 Cessna Skyhawk with a Lycoming O-360-A1A turning a constant
speed prop. I recently read an article in the Cessna Pilot's Association
on too high of oil temperatures, but that is not my case. I have been in
contact with them and they also suggest I get the wisdom of the NG. The
oil temperature does not get anywhere near 180F even during the summer.
I have calibrated the temperature bulb by placing it in a bath of oil
along with a DMM thermometer and heating the oil to 180F and marking the
glass on the instrument. This is a factory OH engine with about 200
hours on it, but the old engine (2000 hrs) did the same thing.

At CPA suggestion I placed a oil cooler restrictor plate that cut down
the airflow opening to 1/3. This is modeled after the C-172M. My oil
cooler is mounted on the back left baffle above the cylinder. I went
flying the other day and it did not seem to affect the temperature at
all from not having it at all.

The 180F mark is in the middle (straight up) and the reading was 1/2 way
between the bottom of the green and the 180F mark. The outside air temp
was about 70F. Hey, its been warm here in North Texas. I was running
about 65% power.

Any ideas from this collective group.

Ross Richardson
a0452593 at ev1 dot net (that is ev one, not little L)

[Orval Fairbairn]

In article >,
Ross and Paula Richardson > wrote:

> I own a '65 Cessna Skyhawk with a Lycoming O-360-A1A turning a constant
> speed prop. I recently read an article in the Cessna Pilot's Association
> on too high of oil temperatures, but that is not my case. I have been in
> contact with them and they also suggest I get the wisdom of the NG. The
> oil temperature does not get anywhere near 180F even during the summer.
> I have calibrated the temperature bulb by placing it in a bath of oil
> along with a DMM thermometer and heating the oil to 180F and marking the
> glass on the instrument. This is a factory OH engine with about 200
> hours on it, but the old engine (2000 hrs) did the same thing.
>
> At CPA suggestion I placed a oil cooler restrictor plate that cut down
> the airflow opening to 1/3. This is modeled after the C-172M. My oil
> cooler is mounted on the back left baffle above the cylinder. I went
> flying the other day and it did not seem to affect the temperature at
> all from not having it at all.
>
> The 180F mark is in the middle (straight up) and the reading was 1/2 way
> between the bottom of the green and the 180F mark. The outside air temp
> was about 70F. Hey, its been warm here in North Texas. I was running
> about 65% power.
>
> Any ideas from this collective group.
>
> Ross Richardson
> a0452593 at ev1 dot net (that is ev one, not little L)


It sounds as if either:

a) Your baffles are extremely efficient.

b) Your sender/gage are out of calibration.

You can check (b) by removing the sender at the next oil change and put
in a cup of water heated to several temperatures and measured with a
candy thermometer. Check the gage against the thermometer.

[Aaron Coolidge]

Ross and Paula Richardson > wrote:
: I own a '65 Cessna Skyhawk with a Lycoming O-360-A1A turning a constant
: speed prop. I recently read an article in the Cessna Pilot's Association
: on too high of oil temperatures, but that is not my case. I have been in
<snip>

A friend's Arrow (IO-360-C1B?) had exactly the same symptom. The oil temp
runs at about 130F no matter what. The Lyc engines have a "vernatherm" to
bypass the oil cooler below some oil temp, and his was hung up wide open.
It's on the co-pilot's side of the oil filter adapter under a big nut with a
copper crush washer. You can heat it in an oil bath to see if it changes,
and check the bore that it rides in for a worn spot that it may catch in.
You can also touch the oil cooler & hoses to see if they're hot/warm/cool.
You could also pull out the dipstick & measure the temperature with your
DMM attachment.
If the oil cooler is pretty warm I'd really suspect the vernatherm valve.
It should be quite cold if the oil is less than 180-ish degrees.
--
Aaron C. (N9376J)

[Ross Richardson]

I did a calibration before, but used oil as the bath. We went to 180F to
get the correct position on the gage face. Although I believe it
correct, I plan to do it again. It is not hard to do.

Ross
Orval Fairbairn wrote:
> snip
>
> It sounds as if either:
>
> a) Your baffles are extremely efficient.
>
> b) Your sender/gage are out of calibration.
>
> You can check (b) by removing the sender at the next oil change and put
> in a cup of water heated to several temperatures and measured with a
> candy thermometer. Check the gage against the thermometer.

[Ross Richardson]

I thougth of that also, but wouldn't I see some rise in the oil
temperature if I restrict the airflow through the oil cooler by 2/3s?
Speaking of Arrow's, I talk to an owner that was putting on a
winterization plate on his oil cooler, and I think it was a plate with a
1.5 D hole in it. That seems like a lot of restriction.

Ross

Aaron Coolidge wrote:
>
> Ross and Paula Richardson > wrote:
> : I own a '65 Cessna Skyhawk with a Lycoming O-360-A1A turning a constant
> : speed prop. I recently read an article in the Cessna Pilot's Association
> : on too high of oil temperatures, but that is not my case. I have been in
> <snip>
>
> A friend's Arrow (IO-360-C1B?) had exactly the same symptom. The oil temp
> runs at about 130F no matter what. The Lyc engines have a "vernatherm" to
> bypass the oil cooler below some oil temp, and his was hung up wide open.
> It's on the co-pilot's side of the oil filter adapter under a big nut with a
> copper crush washer. You can heat it in an oil bath to see if it changes,
> and check the bore that it rides in for a worn spot that it may catch in.
> You can also touch the oil cooler & hoses to see if they're hot/warm/cool.
> You could also pull out the dipstick & measure the temperature with your
> DMM attachment.
> If the oil cooler is pretty warm I'd really suspect the vernatherm valve.
> It should be quite cold if the oil is less than 180-ish degrees.
> --
> Aaron C. (N9376J)

[Aaron Coolidge]

Ross Richardson > wrote:
: I thougth of that also, but wouldn't I see some rise in the oil
: temperature if I restrict the airflow through the oil cooler by 2/3s?

Hmmm, probably, but I can't think of any other reason for cold oil temps.

: Speaking of Arrow's, I talk to an owner that was putting on a
: winterization plate on his oil cooler, and I think it was a plate with a
: 1.5 D hole in it. That seems like a lot of restriction.

My airplane (Cherokee 180, O-360-A4A) has a similar oil cooler cover
plate. I don't usually use it, as my oil temp runs just below 180 in the
winter. If the air temp is realy cold I will put it on. We get 60F days
in the winter here in Southeastern Mass., and the oil temp goes really high
if the plate is on.
--
Aaron C. (N9376J)

[Mike Rapoport]

"Ross and Paula Richardson" > wrote in message
...
>I own a '65 Cessna Skyhawk with a Lycoming O-360-A1A turning a constant
> speed prop. I recently read an article in the Cessna Pilot's Association
> on too high of oil temperatures, but that is not my case. I have been in
> contact with them and they also suggest I get the wisdom of the NG. The
> oil temperature does not get anywhere near 180F even during the summer.
> I have calibrated the temperature bulb by placing it in a bath of oil
> along with a DMM thermometer and heating the oil to 180F and marking the
> glass on the instrument. This is a factory OH engine with about 200
> hours on it, but the old engine (2000 hrs) did the same thing.
>
> At CPA suggestion I placed a oil cooler restrictor plate that cut down
> the airflow opening to 1/3. This is modeled after the C-172M. My oil
> cooler is mounted on the back left baffle above the cylinder. I went
> flying the other day and it did not seem to affect the temperature at
> all from not having it at all.
>
> The 180F mark is in the middle (straight up) and the reading was 1/2 way
> between the bottom of the green and the 180F mark. The outside air temp
> was about 70F. Hey, its been warm here in North Texas. I was running
> about 65% power.
>
> Any ideas from this collective group.
>
> Ross Richardson
> a0452593 at ev1 dot net (that is ev one, not little L

You should check the rating on the vernitherm which is usually mounted on
the side of the cooler. It should have a rating on it. My Helio Courier
has low oil temp too but only because the vernitherm is a 165F unit. I am
thinking about replacing it with a 180F unit. You need to do this before
experimenting with blocking off part of the oil cooler.

Mike
MU-2

[Ross Richardson]

Now that is interesting. When I purchased this aircraft it had the oil
screen instead of the spin on oil filter. The vernitherm was located in
that casting. When I installed the spin on oil filter adapter the
vernitherm was transfered to the adapter. I am not sure of the
temperature rating. How do I tell the rating of the vernitherm since it
is not in the cooler?

Mike Rapoport wrote:
>
> "Ross and Paula Richardson" > wrote in message
>
>
> You should check the rating on the vernitherm which is usually mounted on
> the side of the cooler. It should have a rating on it. My Helio Courier
> has low oil temp too but only because the vernitherm is a 165F unit. I am
> thinking about replacing it with a 180F unit. You need to do this before
> experimenting with blocking off part of the oil cooler.
>
> Mike
> MU-2

[nrp]

Are you certain you still have a vernatherm (i. e. did it really get
transferred?). They are expensive.

My 172M with an O-320E2D on inspection did not. In the winter I can
completely close off the oil cooler air inlet. It will get warm in the
summer with it closed off though.

[Ross Richardson]

Yes, I did the work myself and didn't have one laying around when the
job was completed.

That was my other question to the post on a vernatherm getting stuck
open, shouldn't I see some affect when closing off the oil cooler
opening.

Ross

nrp wrote:
>
> Are you certain you still have a vernatherm (i. e. did it really get
> transferred?). They are expensive.
>
> My 172M with an O-320E2D on inspection did not. In the winter I can
> completely close off the oil cooler air inlet. It will get warm in the
> summer with it closed off though.

[Mike Rapoport]

"Ross Richardson" > wrote in message
...
> Now that is interesting. When I purchased this aircraft it had the oil
> screen instead of the spin on oil filter. The vernitherm was located in
> that casting. When I installed the spin on oil filter adapter the
> vernitherm was transfered to the adapter. I am not sure of the
> temperature rating. How do I tell the rating of the vernitherm since it
> is not in the cooler?
>
> Mike Rapoport wrote:
>>
>> "Ross and Paula Richardson" > wrote in message
>>
>>
>> You should check the rating on the vernitherm which is usually mounted on
>> the side of the cooler. It should have a rating on it. My Helio Courier
>> has low oil temp too but only because the vernitherm is a 165F unit. I
>> am
>> thinking about replacing it with a 180F unit. You need to do this before
>> experimenting with blocking off part of the oil cooler.
>>
>> Mike
>> MU-2

On the ones I have seen the rating is stamped onto the part.

Mike
MU-2

[nrp]

Yes - I believe the vernatherm is a cooler bypass or shunt valve.

You might try blocking the cooler air inlet completely & do a short
flight to see what happens. I used a foam plug wrapped with a
polyethylene bag - all aircraft approved of course.....