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Running too cold?

S

Sig600

Well Known Member
Brain trust...

Weather has cooled here lately (26F this AM), and I'm having some excessive cooling problems. I've got a shutter on the oil cooler, and with it completely shut I still can't get the oil temps above 160. WOT, leaned to peak making as much heat as possible it just sits at 150, CHT's will run 250-270. If I drop full flaps and plow along as slow as possible with as much power as I can carry, I can maybe crack 170 and the low 300's. May try leaving a quart out at next oil change.

Ideas?
 
I run 4 quarts (O-320) fourth winter season and I block oil cooler from BOTH sides. It helps a bit. But my RV sees WOT only on takeoffs unlike your Screamer :D
 
To correct one OWT first, peak egt is not creating max heat possible, except in the exhaust plumbing, and there is no oil there.

The mst heat comes around 50 ROP, but at high powers this is a very stressful position so I would not be recommending that.

Check your sensor is accurate. Look at covering the cooler even more.

CHT is fine.
 
Cold

Time to start "Shrinking the Exit", warmer engine and more speed .
Dan H has a few post about it . Search Shrinking Exit .
 
RV10inOz said:
To correct one OWT first, peak egt is not creating max heat possible, except in the exhaust plumbing, and there is no oil there.

The mst heat comes around 50 ROP, but at high powers this is a very stressful position so I would not be recommending that.

Check your sensor is accurate. Look at covering the cooler even more.

CHT is fine.
Click to expand...

By heat I mean generating high internal pressure to raise CHT...0-50ROP.

It's not sensors, I have two of every thing (8 CHT probes, 8 egt probes,2x oil temp, 2x MAP) to two independent systems, but that's another discussion) and egt/CHT on both systems agree with each other.

Can't shrink the exit more than it is, and if anything I need the air going in to either loiter longer, slow down, or reduce volume.
 
Last edited:
Sig600 said:
Brain trust...

Weather has cooled here lately (26F this AM), and I'm having some excessive cooling problems. I've got a shutter on the oil cooler, and with it completely shut I still can't get the oil temps above 160. WOT, leaned to peak making as much heat as possible it just sits at 150, CHT's will run 250-270. If I drop full flaps and plow along as slow as possible with as much power as I can carry, I can maybe crack 170 and the low 300's. May try leaving a quart out at next oil change.

Ideas?
Click to expand...

Maybe I can bust the other cooling myth. Having a lower oil level doesn't raise your oil temps. It will decrease the time it takes for the oil to reach a steady state temperature, but it won't increase that temperature.

Well unless there's so little oil the bearings run dry and heat up from friction, but for practical purposes oil level has no effect on oil or cylinder head temps.
 
Sig600 said:
Can't shrink the exit more than it is, and if anything I need the air going in to either loiter longer, slow down, or reduce volume.
Click to expand...

"Loiter longer, slow down, or reduce volume" are all (more or less) why you would shrink the exit.

IIRC you use a snorkel, so it would be relatively easy to modify the cowl for swappable winter/summer exits....unless you have pipes in the way.
 
DanH said:
"Loiter longer, slow down, or reduce volume" are all (more or less) why you would shrink the exit.

IIRC you use a snorkel, so it would be relatively easy to modify the cowl for swappable winter/summer exits....unless you have pipes in the way.
Click to expand...

Vetterman quad pipe system, 4 straight pipes in the exit (and a really expensive paint job I'm not going to cut). Not much exit area left to restrict.
 
Got the same issue. Am in the last couple of hours of phase 1.

Before I blocked the oil cooler I could get the oil temp only up to 140 with a 44 OAT. Now I can get it to 160-165 at those temps but if I fly at lower temps I am still running cold.

In the test forum I put a post with a link to my phase 1 summary data so far a couple of days ago. If you look at slide 16 and 17 (this was before I blocked the oil cooler) I only got the oil temp up to 122 and 138 for a 6000 foot climb at Vy (110mph) and Vx (70mph) respectively OAT was around 30 at the start of the climb for those graphs.

Don't have a good solution myself as Lycoming recommends no prolonged operation below 145. If I understand this correctly (and I know very little about engines) the main issue is that water can collect in the oil and won't "burn" off at those temps (can somebody confirm this?). So for now I am just changing the oil more often when it's cold outside until I can come up with something better.
 
spatsch said:
Got the same issue. Am in the last couple of hours of phase 1.

Before I blocked the oil cooler I could get the oil temp only up to 140 with a 44 OAT. Now I can get it to 160-165 at those temps but if I fly at lower temps I am still running cold.

In the test forum I put a post with a link to my phase 1 summary data so far a couple of days ago. If you look at slide 16 and 17 (this was before I blocked the oil cooler) I only got the oil temp up to 122 and 138 for a 6000 foot climb at Vy (110mph) and Vx (70mph) respectively OAT was around 30 at the start of the climb for those graphs.

Don't have a good solution myself as Lycoming recommends no prolonged operation below 145. If I understand this correctly (and I know very little about engines) the main issue is that water can collect in the oil and won't "burn" off at those temps (can somebody confirm this?). So for now I am just changing the oil more often when it's cold outside until I can come up with something better.
Click to expand...

Run 1/2 pint of cam guard, with each oil change. The water issue is moisture that can cause rust on the cam, which cam guard will help prevent along with other wear issues. Where is your plane at? Send me a PM next time you're flyin!
 
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Sig600 said:
Brain trust...

Weather has cooled here lately (26F this AM), and I'm having some excessive cooling problems. I've got a shutter on the oil cooler, and with it completely shut I still can't get the oil temps above 160. WOT, leaned to peak making as much heat as possible it just sits at 150, CHT's will run 250-270. If I drop full flaps and plow along as slow as possible with as much power as I can carry, I can maybe crack 170 and the low 300's. May try leaving a quart out at next oil change.

Ideas?
Click to expand...

Had the same problem on my -8. I installed Van's variable oil cooler baffle, which solved the problem.

-John
 
boomer said:
Had the same problem on my -8. I installed Van's variable oil cooler baffle, which solved the problem.

-John
Click to expand...

OOPs, missed that you had already done this. The other thing I did was replace the oil temp sensor. Turned out my first one was reading about 20 deg cool. Cost less than $25, as I recall.

-John
 
boomer said:
OOPs, missed that you had already done this. The other thing I did was replace the oil temp sensor. Turned out my first one was reading about 20 deg cool. Cost less than $25, as I recall.

-John
Click to expand...

I have two, on two independant systems... Both agree with each other.
 
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