WINTER OIL TEMPS.

[flyer]

My M-5 has the 0360CIF engine. Does it have any provision to automatically bypass the oil cooler when the temperature is low? Do I have to put speed tape on the inlet for the oil cooler air?

Flyer

[Hottshot]

I have my inlet blocked off and it sits juuust rite! Been in temps between 40+deg and down to less than 20deg

[montana maule]

I tape 1/2 of the cooler surface off below +30F and all of it off below O degrees F. At that oil temps still only run 160 to 170 F. I have made a blocking plate on the bottom exit of the cowling that reduces air flow. That helps the cabin heater work better, and helps raise the cylinder head and oil temps.

Rick

[flyer]

Thanks for your replies. Don't these engines have VERNATHERM VALVES that bypass the oil cooler when the temperature is low? Could it be that they do not work properly?

Flyer

[maules.com]

The vernatherm closes off the cooling 'until' the oil temp reaches the prescribed temp, often 175deg if set properly.

[flyer]

It would appear that if the vernatherm valve were working correctly, blocking off the oil cooler would not do anything. The valve should bypass the oil. Since I am not at around 180 degrees, I would think maybe the vernatherm is not set or is not working correctly.

Flyer

[maules.com]

Maybe your oil never reaches 175deg in winter, so the cooler is not in the loop. Check the cooler temp by hand after a flight. The hand can sense up to 120deg. If the cooler is hot, then the vernatherm may be stuck or badly seating ie concentrically, a common case in Lycs, though more with the older style vernatherm.

[flyer]

Good point Jeremy. Is the Vernatherm located in the oil filter base? How difficult is it to remove and fix or replace the valve? If the valve works correctly, blocking off the oil cooler will do nothing. Is that correct?


Thanks

Dick

[montana maule]

When the vernatherm is at prescribed temperature it fully closes and oil is forced throught the cooler. It is not a full on / off valve. Lets say at 100F its full open, at 130F its 50% open, and at 175F its fully closed. If your oil is running at 130F some is being by-passed and some is going through the cooler. Taping the cooler reduces the efficiency and will help the oil to run a bit warmer. Blocking the exit air at the bottom of the cowling also helps with CHT temps. When flying at -10F and below I could only get 200F on the front cylinders. Now I can get them closer to 300F which in turn helps the cabin heat situation.

Also remember the induction system runs through the oil sump. Cold air running through the pipes cools the oil in the sump. I haven't tried it yet but may carb heat would help that situation.

[montana maule]

I called Lycoming today to find out how to test the vernatherm. Put it in oil and heat to 150 to 180F. It should expand a min. of .160". At 250F it should have a max. expantion of .53".

Other than that the only advice they had to raise oil temps was to install the airframe manufactor's winterization kit. Last time I called Maule they said they didn't make one, hence the duct tape and blocking plate.

[g5280]

I just found a site that might interest you. High oil temperature in Continental or Lycoming aircraft engines. http://www.sacskyranch.com/eng18.htm
pretty interesting .Good luck

[flyer]

Thanks for that. Sacramento Sky Ranch does have great information. I liked that description of the Vernatherm valve.


Flyer

[maules.com]

The Sky Ranch Engineering Manual by John Schwaner 916 421 7672 should be on every pilot and mechanic's Christmas wish list.

[g5280]

I just downloaded Mechanics Notepad From Sky Ranch free or $10.00. It looks straight froward it might be an easy way keep track of all the information & data that Jeremy and others have offered oner the years. I know I have notes every where.I got my thumb drive at comp USA on sale 4G $135.00. Thumb drives are grate. Wait until after X-Mas
KEEP M FLYING

[Chopper206]

I use an exhaust tunnel winter baffle down to -39°C. At -40°C I stop flying. The exhaust tunnel winter baffle pressurizes the air in the cowling, making the heaters work better, also cuts down on the airflow through the oil cooler. It fits in plane with the firewall and cuts out about 90% of the airflow through the cowling with a couple holes cut around the two exhaust pipes. I use an Insight GEM to keep track of all the CHT's. The baffle works well up to around -10°C. Tape over the intake or intake baffles creates a vacuum in the cowling. On a few occassions I've launched in a temperature inversion only to find temps above 500' AGL above freezing. Then throttling back to the bottom of the green and mushing along til I get to colder air avoids going back and landing and taking out the baffle. Again, thanks to the GEM I realize the CHT's change as a function of all kinds of atmospheric inputs--temperature, humidity, density altitude, etc. I also blocked the fresh air vent intake at the front of the cowling and re-routed the duct to a Y off the heat muffler so I have three heater ports through the firewall.