Checking O-360-A4A Vernatherm

[Mike Noel]

I decided to check the vernatherm on my Archer's engine because it is
running on the high end of the green during summer flights. I had already
checked the sending unit and guage and found it to be OK. I then removed a
1" hex cap from the top left of the oil filter adapter on the accessory
case. It is a few inched below the elbow that attaches the crankcase vent
tube and so was not easy to get off. I had to grind away a bit of metal
from the outer diameter of a box end wrench to get it to fit between the hex
plug and the metal of the engine. The hex cap is hollow and inside I
found...nothing. I couldn't get a really good look because I had left my
mirror at home, but there was nothing obviously under the plug except a
threaded passage.

Is this where the vernatherm is supposed to be located? If it is and one is
not installed, just what happens to the oil temperature?

--
Regards,
Mike

http://mywebpage.netscape.com/amountainaero/fspic1.html

[[email protected]]

What you describe sounds like a vernatherm from the outside... a 1 inch "nut"
that's only about 1/8" thick on the oil filter plate. The vernatherm works opposite a
car thermostat, though. Rather than requiring to operate to cool, it must operate to
*not* cool. It's got a tapered plug on the end that extends when heated. Rather than
me try to describe it poorly, check out:
http://www.sacskyranch.com/eng18.htm


Mike Noel > wrote:
: I decided to check the vernatherm on my Archer's engine because it is
: running on the high end of the green during summer flights. I had already
: checked the sending unit and guage and found it to be OK. I then removed a
: 1" hex cap from the top left of the oil filter adapter on the accessory
: case. It is a few inched below the elbow that attaches the crankcase vent
: tube and so was not easy to get off. I had to grind away a bit of metal
: from the outer diameter of a box end wrench to get it to fit between the hex
: plug and the metal of the engine. The hex cap is hollow and inside I
: found...nothing. I couldn't get a really good look because I had left my
: mirror at home, but there was nothing obviously under the plug except a
: threaded passage.

: Is this where the vernatherm is supposed to be located? If it is and one is
: not installed, just what happens to the oil temperature?

: --
: Regards,
: Mike
:
: http://mywebpage.netscape.com/amountainaero/fspic1.html



--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering Ph.D. Graduate Student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[[email protected]]

My 1975 172M (Lyc 150 HP O-320E2D) likewise had no vernatherm when I
checked. It apparently must be common to leave them out as they are
expensive. I don't have a problem with oil temp except that it many
times runs too low. Do you have high oil temps?

[Mike Noel]

Turns out I was looking in the wrong 'hole'. The vernatherm was in an
extended housing on the bottom side of the oil filter adapter and did
contain a vernatherm. However the seat at the end of the plunger was
unevenly worn, with one side worn in a bit and the other side showing only
slight contact. My mechanic is ordering a new vernatherm and will also
resurface the seat inside the oil filter adapter. If that doesn't fix the
oil temp, I'm going to have the oil cooler removed and flushed by Pacific
Oil Cooler or someone equivalent.

Anyone have any good or bad experiences to share with oil cooler cleaning?

--
Regards,
Mike

http://mywebpage.netscape.com/amountainaero/fspic1.html
> wrote in message
om...
> My 1975 172M (Lyc 150 HP O-320E2D) likewise had no vernatherm when I
> checked. It apparently must be common to leave them out as they are
> expensive. I don't have a problem with oil temp except that it many
> times runs too low. Do you have high oil temps?