Alan Carroll

Alan Carroll

Well Known Member
With the return of warm weather I?ve been seeing abnormally high oil temperatures, compared to several years of past observations. Engine is an O-360-A1A, Hartzell, and Niagara oil cooler from Van?s. Typically oil temperatures in the past were in the low to mid 190s in warm weather (ca. 75-80? OAT at 2500?, power at 24/24, 10.5-11 gph). This year however I?ve seen 218? after 20 minutes flying. Something definitely changed over the winter.

I?ve been through the usual list of things to check and nothing else has changed: condition of baffles, oil cooler mounting/condition, cylinder compressions, CHTs, EGTs, oil pressure, oil consumption, performance. No obstructions in the oil cooler lines or passages. Checked the temperature probe in boiling water and it was spot-on (210? at 900? elevation). Changed the oil and filter, cut open the filter, checked the oil sump screen. I sent the oil cooler to Pacific Oil Cooler to be flushed, and they also tested the vernatherm. Acccording to their report it expanded by 0.239?, well within tolerance. No improvement in oil temp after reinstalling however.

Today I tried installing an oil cooler bypass plunger and spring. As described in previous threads, the plunger effectively shuts off any flow past the vernatherm and sends it all to the oil cooler. I left the vernatherm installed for now (I have a straight Lycoming filter adaptor).

Flying under similar conditions as before, oil temp today topped out at 200?, about an 18? improvement. I?m not sure if I?ve fixed the original problem, or just masked it, but the plunger made a substantial difference. I will need to decide whether to buy a new vernatherm, or leave the plunger in place and install a ball valve as Larry Vetterman has done.
 
Where did you buy the plunger?

Where did you buy the plunger... and where does it go?

I have the same engine that you have. I have been chasing down high oil temps as you have described with out success. At this point in the game I would be thrilled with 200 degree oil. I just got back from a flight tonight. The outside air temp when I took off was 97F. Sadly.... at almost 10:00 pm it is still 95F. At 2500 msl the temp dropped to 93F I climbed full rich using about 12 gal/hr. Upon reaching 2500 I decreased the power to 24inches and 2600. After the oil got to 230, I went back to maximum power settings to increase my airspeed... but I could only fly like this for maybe a minute as the oil temp came to 245. I reduced the manifold pressue to 19 inches and the RPM to 2100. I also went to a nearly full rich setting. With all this the oil temp came down to about 230 in about 10 minuntes.
 
I got the parts from A.E.R.O. in Granite City Illinois. Part numbers are 62415 (plunger) and 69436 (spring), and MS35769-11 (gasket). The plunger installs in the accessory case, just below the tach drive. There has been some previous discussion of this which is helpful, for example start at post #23 in this thread:

http://www.vansairforce.com/community/showthread.php?t=60008&highlight=plunger+oil&page=3

Sacaramento Sky Ranch also has a good discussion; basically what I did was to reinstall the older "viscosity valve" which predated the vernatherm:

http://www.sacskyranch.com/eng18.htm

I should point out that I'm not an A&P or engine expert, and therefore am not advocating this mod for anyone else!
 
resurrection

Howdy

Resurrecting this thread as I am considering this mod to make a measured test of the oil temp difference before and after.

Since the thread is about a year old does anyone have any long term experience with this mod to report?

Thank you,
 
You must log in or register to reply here.