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Low oil temp

JackinMichigan

JackinMichigan

Well Known Member
In the winter months in Michigan I've noticed that during normal operations my oil temp hovers around 150 degrees. I haven't thought much of it, but the instructor I've been flying with for the past few weeks seems to think it's a big problem. He claims that it's not hot enough to evaporate away all the residual moisture that can sometimes build up inside the engine, and allowing it to go on for long will shorten the life of the engine.

To fix the problem, so he recommends, remove the cowl and wrap a portion of the oil cooler with aluminum foil tape. I haven't done it yet, mostly because the lower cowl is such a PITA to remove, but is this really as big a problem as he claims?
 
JackinMichigan said:
In the winter months in Michigan I've noticed that during normal operations my oil temp hovers around 150 degrees. I haven't thought much of it, but the instructor I've been flying with for the past few weeks seems to think it's a big problem. He claims that it's not hot enough to evaporate away all the residual moisture that can sometimes build up inside the engine, and allowing it to go on for long will shorten the life of the engine.

To fix the problem, so he recommends, remove the cowl and wrap a portion of the oil cooler with aluminum foil tape. I haven't done it yet, mostly because the lower cowl is such a PITA to remove, but is this really as big a problem as he claims?
Click to expand...

Search on oil cooler shutter. Lots of discussion on this topic. Low (below 180F) temps probably are not good.
 
Engine wear is reduced at temps of 180? F. I have to block off part of my cooler even in the summer months to keep temps up. I like 180-190?.
 
Kyle Boatright said:
Why not just pull the top cowl and partially block the 4? SCAT hose feeding the cooler? An aluminum plate would work fine.
Click to expand...

This is basically what I do with out Tundra in the cold months - I tape whatever scrap of thin aluminum I have handy that covers half the opening, and tape it in place with aluminum tape.
 
Shutter and restricted cowling opening

I have a oil shutter but with it completely closed, the oil stay too cool below -5C ( 23F)

I made a winter kit to restrict the air from the cowling front opening. Now i can get my oil to 175-180. Mainly to let the moisture evaporate from the oil.

Here is a picture.


https://untilidie.home.blog/winter-kit-rv-10/
 
I tend to agree with your instructor in that you need to get the temps up. The Lycoming 540 Operator's Manual states "For maximum engine life, desired oil temperature should be maintained between 165*F (73.8*C) and 200*F (93.3*C) in level flight cruise conditions." YMMV....
 
I put the throttle valve from TCW Tech on both my RV-10 and RV-14. You can use it to get the temps right where you want. Used it just last week on my RV-10 that wouldn't get out of the low 170's in the central US at higher altitudes. I don't use it with the servo controller though. For something like the oil cooler, I prefer an actual manual cable to operate it. If something were to happen that you couldn't control it, you could end up with blocked cooling and get pretty hot. So I keep it simple.
 
Temp

Yea pour water on a 150 degree surface and
it will never go away, be there for days.
Seriously, if you fly over 45min. to and hour
at a time shouldn?t be that big of a deal, or
just add a little bit of thinner wt. oil and press
on.
 
I second Tim O response. Get the TCW oil cooler valve. I can adjust my oil temp to almost exact temp I want to run at in the winter months. I feel this is a must on the RV10 if you fly in any temps below 55F. Last week flying from Ohio to south Florida I adjusted to keep my temps at 188F. I have had mine on my RV10 for 10 yrs now. Works great
 
Same problem with my -7, I installed the Anti-splat oil cooler shutter with a cockpit adjustable Bowden cable. That did the trick!
 
The "residual moisture" commentary seems to have attained myth status, kinda of like the "never run MP higher than the RPM" myth which traces its origins back to the radial engine days.

How often do you change your oil? If it's every 25 or 50 hours, residual moisture should be no problem even running at temps cooler than 180 degrees. And a cool running engine will outlive a hot running engine. Years ago, my Lycoming guy told me the residual moisture is only an issue for engines that are run for 100+ hours without a change.

My own engine (O-360) installation only ever exceeds 180 degrees on hot summer days (Texas) and even then has never hit 190. I usually see temps in about 160-175 range depending on time of year. After 800+ hours (knock on wood) the engine still runs strong. I change oil every 25-30 hours. And recently, I switched to changing the filter every 50 hours.

Seems to work.

Chris
 
Sue said:
Yea pour water on a 150 degree surface and
it will never go away, be there for days.
Seriously, if you fly over 45min. to and hour
at a time shouldn?t be that big of a deal, or
just add a little bit of thinner wt. oil and press
on.
Click to expand...

The dew point of exhaust gas is somewhere in the 53C/130F range. So, during the initial operation of the engine, water is condensing into the oil (from combustion gases blowing by the ring). Once the oil reaches 130F, water stops condensing in it. As the oil warms past 130, the process starts to reverse. The question is the ratio of times/temps below and above 130F.

Having flown with a cockpit adjustable throttle on the oil cooler (in MN) for 18 years, I cannot imagine not having one. With OAT's at -5F, I can still achieve 170F on the oil temp fairly quickly.
 
There's one other factor that people are completely missing out on as well. In the winter, where I fly, it may be 0 degrees or even lower on some days. Whey flying from home, I have it pre-heated so it's not too big of a deal as the run-up doesn't take too long to warm up. But, when you fly somewhere else, like I did a couple weeks ago, and the engine is cold-soaked into the 30-40 degree range, you're going to be looking at a long wait to warm up. I had dinner and a conversation and was in the 30's when I was done and ready to depart.
With the throttle valve, I am able to close it almost fully and prevent further oil cooling while I'm doing my taxi and run-up and warm up. I don't ever depart until I'm over 100F on the oil temps. I also often pull the valve shut on descent on the colder days to keep the engine warmer.

If I lived and flew only in the Southern part of the US, I may not add the valve. In fact, I didn't have them installed in either plane until a year or two experience on each. But when living where I do, I find I use the valves quite a bit from November thru April. Less so after that.
 
From the control valve servo page:

Use Standard kit (30mm travel) with Van's RV heater valves and TCW butterfly valves.
 
Feedback:
Previous to that install half of my cooler was blocked by a fixed plate. With OATs around freezing my oil Ts usually kept hovering around 150-160F (O-360 using sedate settings, typically 19/2000, reduced FF and noise, and I love to fly :))
Installed the excellent shutter from Anti-Spat with a Bowden to the cockpit. Went for a buzz yesterday and found that I'm now able to maintain the ideal 180F. With the shutter fully closed... wonder why to have the oil cooler in the first place ;)

PS
Also been flying in pretty hot weather last year, namely Spain with an OAT of 43?C (109.4F), and the oil was still well below 200 (remember, 1/2 of cooler blocked). Guess the engine would still be happy with a smaller oil cooler...
 
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