Really cold weather operation

[rainman]

My question for you guys/ladies who fly in the frozen north is this. Yesterday, I flew from south central Texas to Willmar MN to drop of my 231 for a tank strip and reseal. When in Minnesota, the oil temp was in the 130s. It was -18 on the ground at Willmar and the oil temp would not go above 140. The question is what do you do to mitigate the problem of moisture in the engine since the oil didn't get hot enough to evaporate the water? By the way, the guys at Weepnomore were very nice, flying me to Minneapolis to catch a flight home to Texas! Ray

[Bob_Belville]

I wonder if one could block or partially block airflow through the oil cooler? Think the canvas radiator covers on diesel trucks used in the winter. But then again I don't suppose the vernatherm valve is allowing flow through the cooler at those low temps anyway. Perhaps restricting cooling air to the engine by modifying the openings @ the cowl flaps?

 

I'm just guessing, Some of the MS folks who routinely fly in cold regions will give you some ideas.

[FlyDave]

I know the Rocket Engineering Missile conversion has a "weather plate" that can be installed in the cowl opening to partially block the airflow.

My J had a plate that partially covered the #1 cylinder but that made #1 20-25 dF hotter than the rest in climates that are more temperate. This plate was not removable.

[flyingvee201]

I would think you could fabricate a simple metal plate to temporarily place over the oil cooler or cooler opening. Of course the plate needs some holes in it so not to completely block the airflow.

Pilots in Alaska do this all the time, but im sure its "ONLY" for bush planes with tundra tires and not for Mooneys!!  LOL

[Dave Marten]

My old Bo had a cold weather plate. For your K I wouldn't worry about the 'short term cold exposure' due to your Wilmar visit. On your flight south you'll get her back up to temp.

 

Other cold tips - close cowl flaps on start/ground ops. Takeoff with cow l flaps partially open and open full only if required base on actual engine temps (CHT/oil).

[BorealOne]

Gents - welcome to winter! Mooney does offer winterization kits for several airframes (basically, a metal plate cover for the cooler with an official sticker that warns 'CAUTION - This door shall be removed and stowed when field temperatures exceed 30ºF -1ºC') that most of us who fly the really cold skies install somewhere around the end of October and leave in place until April. It does an excellent job of keeping the oil in the green, except when the OATs get down towards -40.

 

This is actually more critical than just allowing the oil to boil off moisture - the vernatherm into the cooler comes alive above 150F, but if you've got a cooler full of oil the consistency of toothpaste, it will never fully open, creating a high pressure point within the oil system and in a worst case scenario, blow a hose or seal, making for a very bad day.

[aaronk25]

Go to Home Depot get the 3/8" or 1/4" fool faced bubble insulation that's used to wrap around heat ducts. Cut a piece about 3-4" tall and the width of the oil cooler plus 4". Then lay the piece directly up against the oil cooler and make 2-90 degree bends to go up the side of the oil cooler sleeve and secure using foil tape or gorilla tape. Done! The foil face won't damage the cooler nor will it melt if it gets to hot. The tape won't melt as it can take quite a bit if heat and the aluminum between the cooler and engine doesn't get to hot.

There piece should only block off about 3/4 of the cooler as you will want some air going through. I'll take a pic if I decide to freeze today and pull my cowl off.

The other thing I like about this is if you fly down south and oil temp rises land and reach in under cowl and tear it out, without removing the cowl.

[mike_elliott]

My question for you guys/ladies who fly in the frozen north is this. Yesterday, I flew from south central Texas to Willmar MN to drop of my 231 for a tank strip and reseal. When in Minnesota, the oil temp was in the 130s. It was -18 on the ground at Willmar and the oil temp would not go above 140. The question is what do you do to mitigate the problem of moisture in the engine since the oil didn't get hot enough to evaporate the water? By the way, the guys at Weepnomore were very nice, flying me to Minneapolis to catch a flight home to Texas! Ray

Did you see Bill G's Bravo getting worked on there, Rainman? While a long trip from Texas, it was the right trip if you want your tanks fixed once and for all. You wont have to worry about them for another 30 or so years. The newer sealants plus Pauls attention to detail when it comes to the sealing and stripping process is much better than what was coming from the factory and should last much longer. On that note, Paul is a sponsor of the Mooney Summit and will have a discount program available for the attendees. Thanks again for this, Paul! 

[rainman]

Aaronk25, I may need to do what you suggest when it comes time to take it home in a couple of weeks. A photo might help. Thanks everyone for the info. Ray

[Jeff_S]

I wouldn't worry too much about moisture. When it's that cold, the air can't hold any moisture anyway. I used to have an oil cooler plate for winter ops in my Warrior but I've not heard of such a thing for a J.

[aaronk25]

Aaronk25, I may need to do what you suggest when it comes time to take it home in a couple of weeks. A photo might help. Thanks everyone for the info. Ray

This is the stuff. I

[tony]

deleted

Edited December 24, 2013 by tony

[pinerunner]

I wouldn't worry too much about moisture. When it's that cold, the air can't hold any moisture anyway. I used to have an oil cooler plate for winter ops in my Warrior but I've not heard of such a thing for a J.

It is a concern. The dryness of the air doesn't enter into it since we're generating 46 gallons of water for every 52 gallons of fuel (freshman chemistry calculation based on octane). Most of that goes out the exhaust of course but any blow-by ends up going through the crankcase and can get in the oil. Normal oil won't dissolve much so water being heavier than oil it will tend to sink to the bottom of the sump. They talk about additives that help keep it in suspension but I don't know much about that. I've seen 180 degrees F mentioned as a minimum. On car sites I've seen 200 degrees F put forward as an ideal. I wouldn't be content with low oil temperatures. The additives may help but they'll have a maximum capacity so frequent oil changes may be indicated in winter.  

[Bob_Belville]

The engine shop owner who has my engine would be less worried about 220 oil temp in summer climb than 160 in winter cruise. He want the water boiled out of the oil.   

[Shadrach]

Just use aluminum tape. It goes on easily and stays on, yet is easily removed. It will conform to the cooler face and completely block however much of the cooler you decide to block. It is infinitely modifiable to get coverage that yields the oil temp of choice...

[Bob_Belville]

Ross, I'm curious whether in extreme cold weather, with CHTs ~300F, if the oil gets hot enough to open the vernatherm valve.... and if not, whether it makes much difference to block air through the oil cooler.

[pinerunner]

Its not a matter of opening to the oil cooler but of closing off the by-pass according to this article.

 

http://www.oilcoolers.com/article_oil_cooler_woes.asp

 

Scary pictures of popped oil coolers due to insufficient preheating can be seen and a nice simple explanation of how it happens. Scariest case would be an actual rupture and loss of oil pressure.

 

I don't know first hand that they're right but it sounds true.  I've just switched to multigrade for the winter after a period of inactivity. 

[Guest]

Hello Larry,

How are things in the west?

Your Ovation has the factory blocker plate as do most of the ones I've worked on. Some 252 s have one as well. Any other model needing one has to be invented by the owner or maintainer.

Clarence

[rainman]

Can someone post a photo of one of the plates in place? Ray

[aaronk25]

Ross, I'm curious whether in extreme cold weather, with CHTs ~300F, if the oil gets hot enough to open the vernatherm valve.... and if not, whether it makes much difference to block air through the oil cooler.

As per my recent post it makes a big deal on my m20J. When the oil cooler congealed and stopped passing oil at 75% power -38c. The oil went from 163 to 235 or so in about 10 mins. I know some 172s with 150hp don't have a oil cooler but these higher output engine seem to transfer a lot of heat to the oil.

[Bob_Belville]

As per my recent post it makes a big deal on my m20J. When the oil cooler congealed and stopped passing oil at 75% power -38c. The oil went from 163 to 235 or so in about 10 mins. I know some 172s with 150hp don't have a oil cooler but these higher output engine seem to transfer a lot of heat to the oil.

I'm thinking blocking the air through the cooler would not have helped. From the Pacific article, the important caution is to start out with warm oil, including the oil in the cooler.

[jlunseth]

Getting the whole engine compartment, including the oil and oil cooler fully warmed, is very important.  It may mean sitting for 10 minutes or so before taxiing, but you must do it in super cold weather.

 

However, blocking the cooler also is very important and it does help.  I have seen two issues, the first is that the blast of cold air at ground level (where the air is very "thick") that is experienced by the engine on takeoff, can undo in a minute all the warming up work you have done.  I have found it is important to keep the cowl flaps SHUT during ground operations and on takeoff in these conditions.  Taxiing and particularly taking off with the flaps open, will undo with immediacy all the warming up that you have done back at the ramp.  The other issue with the oil cooler is longer term.  Everything may be fine on takeoff, but given enough time at low altitudes and cold temperatures, with no oil cooler block, you will see the oil temps fall to minimum operating temperature, give or take just a few degrees (meaning maybe a few degrees below minimum operating temp. which is not good).  So you will be in the worst of all worlds, running the engine as hot as you can, with consequent high internal cylinder head pressures but low CHT's, and the oil on the verge of jelling at some point in the engine, such as in the oil cooler, where it is getting exposed to supercold air.  This will eventually happen without the cooler, even if you have spent an hour on the ramp warming the engine compartment.

 

My last oil cooler was two pieces of open cell foam taped together and cut to fit into the cooler.  It worked very well.

[Shadrach]

Bob,

 

2 things:

 

1) Blocking the cooler does more than just keep the cooler from exchanging heat, it also prevents a large volume of air from entering the cowl, unless you have a 201 or later or a vintage bird with the cooler relocated.

 

2) IIRC, the vernatherm does not block the oil cooler, it blocks the direct return path to the engine forcing oil through the cooler. When the engine is cold, most of the oil bypasses the cooler but as it warms up to temp, the vernatherm blocks the direct path to the engine and oil is directed to the cooler.

 

I'm sure there are several reasons the system was designed not to "block" the oil cooler. The 2 that seem most obvious to me are 1) if the device failed in blocked mode  you could end up with a severe overtemp which is much worse than under temp in the short term. and 2) if flow was completely blocked to the cooler, any oil remaining in the cooler would congeal in very cold temps (especially for those that insist on running straight weight year round), the cooler needs a steady stream of warm oil to prevent congealing.

[mike_elliott]

Bob,

 

2 things:

 

1) Blocking the cooler does more than just keep the cooler from exchanging heat, it also prevents a large volume of air from entering the cowl, unless you have a 201 or later or a vintage bird with the cooler relocated.

 

2) IIRC, the vernatherm does not block the oil cooler, it blocks the direct return path to the engine forcing oil through the cooler. When the engine is cold, most of the oil bypasses the cooler but as it warms up to temp, the vernatherm blocks the direct path to the engine and oil is directed to the cooler.

 

I'm sure there are several reasons the system was designed not to "block" the oil cooler. The 2 that seem most obvious to me are 1) if the device failed in blocked mode  you could end up with a severe overtemp which is much worse than under temp in the short term. and 2) if flow was completely blocked to the cooler, any oil remaining in the cooler would congeal in very cold temps (especially for those that insist on running straight weight year round), the cooler needs a steady stream of warm oil to prevent congealing.

 

Ross, on your F, if the cooler hasn't been relocated, and you have the lower cowl closure, the airflow might actually be FROM the lower cowl area out the front to the low pressure area created by the vintage cowl. The lower cowl area is somewhat pressurized by the flow of air from the upper cowl area. That said, I did congeal the oil in my cooler once in sub zero temps, even with the conditions I just described.

[Bob_Belville]

Ross, my oil cooler is relocated so the air through it comes across the top of the port cylinders. I suppose blocking air in this case is less important. For one thing, diverting air from the oil cooler moves more air thru the post cylinders perhaps cooling those cylinders more than the starboard side which is typically hotter already.