Oil Cooling Blast Tube

[6597]

There is a cover for the blast tube part# 0450310 you can fashion one easily or try tape. I think it says something like 'remove above 70 degrees'. Check the parts catalog to get an idea under 'winterization kit'.

There is an oil tank cover part# 0450316 to help keep the oil warm. WagAero sells something like a tank cover but I have no experience with it...
https://www.wagaero.com/catalogsearch/r ... tank+cover I suspect it would take some finagling to fit. Will probably get oily over time. There are covers for the pushrod tubes also in the kit I think.

Yes do cover the 2 holes under the prop hub.

I don't understand

additional tape on the bottom exit of the cowl by the breather ( only 6” inboard).

I cover my grills about 1/4 or slightly more in the winter, but I"m in the pacific northwest with a fairly maritime climate. Home made covers

4-13-15 009.jpg (230.96 KiB) Viewed 5215 times

There's a schematic for making a nice set, probably in the club maintenance manual?

[6930]

Five below already! Holy smokes! You’re making me feel downright balmy in Northern Illinois.

Personally, I don’t fly when it is that cold. Others that do, and have more experience on this, can weigh-in…but I would recommend covering the blast tube hole for sure. The parts manual shows the blast tube cover and recommends it be removed at temperatures over 70 Deg F.

Second, if you haven’t already done so, I would consider adding the oil sump cover. Again, shown in the parts manual (winterization kit). I don’t recall what temperature criteria is used for installation, but certainly anything under 10 or 15 deg F would warrant doing so in my opinion.

And yes, I would be seriously concerned about shock cooling. I worry about it when it is plus 20 Deg and avoid power off glides.

Stay warm!

[6643]

My recollection is the blanket for the oil tank comes off at 40 degrees F. The Wag Aero kit includes covers for the intake tubes, but I never tried to put them on.

Optimum oil temperature is about 180 degrees F. This means it gets hot enough passing through the engine to boil off any moisture it accumulates from condensation and combustion. If you fly a lot and can't get it that warm, consider changing the oil more frequently. Combustion byproducts plus moisture yields acids...

I cringe whenever I hear something like "the oil sensor/screen blast tube". It's just a coincidence that the oil temperature sensor is there and not somewhere else. The purpose of the blast tube is to cool the oil before it goes back into the engine. Years ago there was a rumor spreading around that the point was to trick the gauge into reading lower, as if it was somehow reading higher than the actual oil temperature. It just ain't so... And if it were, the solution would be to re-calibrate the gauge.

[lampak25]

Thanks for the info. The tape on the bottom of the cowl that restricts outflow in my mind would create more pressure inside the cowl, keeping a bit more heat inside.

[lampak25]

I’ve flown the past 2 days.

SFC Temps 1000 AKST -16F, -20F
Inversion layer at 400-500 agl @Alt. 20-24 F

I placed foil tape covering the lower inlets below the spinner, 1/4 coverage from the prop side of the cowl inlets, also covered half the blast tube that leads thru the baffling from behind cyl #1.

Oil temps on climb out were 130-140F.

Cursing at 2400 rpm at 1000’ agl OAT 20F temps maintained.

Yes I want them higher, I’ve very attentive to preheating, both the engine and cockpits prior to flight. I plan to change the oil more frequently during the winter, 15 hours apart. My engine baffling also needs some attention. Any other cold wx pilots have tips or trips?

Lucky for me, it’s not too cold. Did moat of my PPL last winter in -20 to -30F. Super fun!

[6643]

If the blast tube is on the oil screen housing, block it off completely. (If it's on the generator, don't block it at all. If it has any effect on oil temp, leaving it open will increase oil temp, but it probably won't make a measurable difference). Also, you can block all of the cowl inlets in front of the cylinder barrels (about 1/3). Do not block the area in front of the cylinder heads.

[edidin]

Not wanting hi-jack this topic but it’s related to oil temps…mine are quite cold. Today, at -5F surface temp, oil temp was 115F at startup, 95 at take off and after 500 agl climb temp was at 112F. These temps where produced while both vents under the prop are taped over and additional tape on the bottom exit of the cowl by the breather ( only 6” inboard).

My big concern comes from descent to land. On final temps fall below 90F and this was after a 2 hour cruise. I understand raising oil temps in sub zero temps on a C85 is tough but when is oil temp too low?

Would covering up the oil sensor/screen blast tube be the wrong way to have a high oil temp reading.

My oil temp reading is coming from a CGR-30P

Do you block the main grills at all like with winterization kit? I have to to get winter temps reasonable.

[lampak25]

I blocked off the inside third of each cowl inlet. Oil temps stay in the 140’s. Also have low CHT. All temps within +/- 30 F, but peak is 190. One twist that I learned today is that the EI engine monitor I have installed has a CHT probe (p-100)that is not contact the CH wall but rather the air temp inside the hollow where the probe is placed.

List of fixes:
1) repair baffling. It’s not terrible but needs replacing
2) replace the CHT probe to p-101 (bayonet style)