cold weather oil temp's
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
cold weather oil temp's
Hi gang i got a question aboout oil temp's in the cold winter cond. I have been flying around home lately with temp's in the 20's and my oil temp. will not go above 100 deg. I have my oil pan hole blocked and just wanted to know if this is normal. this is my second winter in it and last year my oil temp gage took a dump so i don't know what it was reading last winter so any info would be great.
- Bruce Fenstermacher
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We'll assume your oil gage is working correctly now.
100 degrees seems a little cool but I'm not surprised. You need to block of probably as much as half of the from cool air intakes.
Here is one of many threads about this very thng.
http://www.cessna170.org/phpBB2/viewtopic.php?t=3029
100 degrees seems a little cool but I'm not surprised. You need to block of probably as much as half of the from cool air intakes.
Here is one of many threads about this very thng.
http://www.cessna170.org/phpBB2/viewtopic.php?t=3029
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
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You should try to get about 180 so as to rid the engine of any condensate.
with the sump and inlets plated I would red line the oil temps in high cruise, I removed the sump plate and I cruise in the range of 190. But then again my temps were always a little high.
with the sump and inlets plated I would red line the oil temps in high cruise, I removed the sump plate and I cruise in the range of 190. But then again my temps were always a little high.
Vic
N2609V
48 Ragwing
A Lanber 2097 12 gauge O/U Sporting
A happy go lucky Ruger Red label 20 ga
12N Aeroflex
Andover NJ
http://www.sandhillaviation.com
" Air is free untill you have to move it" BB.
N2609V
48 Ragwing
A Lanber 2097 12 gauge O/U Sporting
A happy go lucky Ruger Red label 20 ga
12N Aeroflex
Andover NJ
http://www.sandhillaviation.com
" Air is free untill you have to move it" BB.
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- Joined: Tue Aug 09, 2005 9:49 am
cold air
Thanks for the info. now i have a good reason to go back out to fly in the cold. think iam going to try the blast tubes and cyl. inlet's should do the trick. Bruce did i meet you at sentimentle this past summer? my 52 is polished with blue trim...........
Cold weather oil temps
Covering up the blast tubes that duct air to the oil screen does not really raise your oil temp. It only increases the indicated temp by raising the temp at the sensor in the screen. If you want to really scare yourself, leave the cover over over the blast tube and see what happens to your indicated oil temp on a 90 degree August day. If it makes you feel better, go ahead, but your oil temp really does not change as much as the guage indicates. Like many of us, my oil temp barely comes off the peg on cold days. I have a cover over my oil cooler inlet the winter months. Fortunately, in Tennessee we rarely get temps lower than the high 20's. I do condone using multi weight oil in the winter months. Seing the oil pressue guage come to life instantly on a 30 degree day is comforting. With 100W, it seems like you could die of old age waiting for the needle to move. ONLY FIVE MONTHS TO THE PETIT JEAN 170 FLY IN. For any of you who are within weekend flying distance of Arkansas, do not miss it. If you are curious, check the postings in the Fly In's forum.
- Bruce Fenstermacher
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Bodine it was me at Sentimental Journey. Will be there next year as well. Perhaps we should have a 170 gathering there.
I agree with t7275tr. Blocking the blast tubes only raises the indicated oil temperature and won't raise the overall oil temperature significantly.
I have the older non-pressurized cowl. I block 2 out of the 4 openings horizontally and block the oil sump cooling hole as well. My temps will make it over 180 in 20 degree weather. BTW I use a plane old round inspection cover for a rag wing to cover the oil sump cooling hole.
I agree with t7275tr. Blocking the blast tubes only raises the indicated oil temperature and won't raise the overall oil temperature significantly.
I have the older non-pressurized cowl. I block 2 out of the 4 openings horizontally and block the oil sump cooling hole as well. My temps will make it over 180 in 20 degree weather. BTW I use a plane old round inspection cover for a rag wing to cover the oil sump cooling hole.
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Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
The oil temperature sending bulb is located in the center of the output oil screen and is surrounded by oil. Oil is the medium that transfers its temperature to the sensing bulb. That's the oil temperature as the oil starts its journey through the oil galleys of the engine. That starting point is the standard location for oil temperature sensing on all engines with pressure lubrication.
BL
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You're correct that I do not know how much (if any) cooling those blast tubes are doing, but now with that cold air blocked off I do feel my gage more accurately reflects the true temperature of the oil. And it does make me feel better to see my needle in the middle of the range now instead of way at the bottom.N9149A wrote:I agree with t7275tr. Blocking the blast tubes only raises the indicated oil temperature and won't raise the overall oil temperature significantly.
Corey
'53 170B N3198A #25842
Floats, Tundra Tires, and Skis
'53 170B N3198A #25842
Floats, Tundra Tires, and Skis
An AP friend says you want to get the oil temp above 160 once and a while to boil off the acids in the oil??
Duct tape, duct tape, and more duct tape.
Oil 15w-50 year round.
As temps drop in the fall
1st. Blast tubes on rear baffle taped up.
2nd. Oil cooler hole on from nose bowl (this is progressive)
3rd. Front cowl openings this also progressive starting on the inside and moving out. Not much past the cylinder barrels about half way is as far as I go.
Flying back the other day my temp were as follows:
OAT Oil Temp
10F 185
0F 165
-10to-20F 140 to 145 this was while desending and doing low level scouting.
Duct tape, duct tape, and more duct tape.
Oil 15w-50 year round.
As temps drop in the fall
1st. Blast tubes on rear baffle taped up.
2nd. Oil cooler hole on from nose bowl (this is progressive)
3rd. Front cowl openings this also progressive starting on the inside and moving out. Not much past the cylinder barrels about half way is as far as I go.
Flying back the other day my temp were as follows:
OAT Oil Temp
10F 185
0F 165
-10to-20F 140 to 145 this was while desending and doing low level scouting.
There is an opinion that is commonly held, that the blast tubes' purpose is to blow air onto the probe to "trick" the oil temp readouts. I feel that is an incorrect interpretation.N9149A wrote:I agree with t7275tr. Blocking the blast tubes only raises the indicated oil temperature and won't raise the overall oil temperature significantly.
The oil suction screen, where the blast tube directs it's air, is the pickup point for the oil pump. The design criteria for the engine calls for oil temp readings to be taken at the oil "inlet"....and the screen is indeed the inlet point of the system (since it happens to be where the pump picks up the oil for distribution.)
The blast tubes help assure that the oil temps in the screen are kept at the specified "inlet" temp.
If, the oil in the inlet (screen) is denied cooling air in the winter.... does that mean the oil temp we see indicated in the cockpit is no longer valid? Does it only raise the "indicated oil temperature and won't raise the overall oil temperature significantly"? I don't think so.
I think that if the oil in the sump is running 180 degrees, and the blast tubes lower it at the screen where it enters the pump, down to 120... then blocking that blast tube so that the indications come back up to 180.... is a valid indication of the oil in the sump AND the screen. This is because the screen is no longer contributing to the cool-down of the oil on it's way to the pump inlet. In other words... if the blast tubes are blocked off...then the blast tubes will no longer COOL the oil down as they did before. The oil reaching the inlet will be more like that in the sump. (But truly,....it will not actually "raise" temps above that already in the sump.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
- Bruce Fenstermacher
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- Joined: Tue Apr 23, 2002 11:24 am
George I think we said the same thing differently.gahorn wrote:....... In other words... if the blast tubes are blocked off...then the blast tubes will no longer COOL the oil down as they did before. The oil reaching the inlet will be more like that in the sump. (But truly,....it will not actually "raise" temps above that already in the sump.)N9149A wrote:I agree with t7275tr. Blocking the blast tubes only raises the indicated oil temperature and won't raise the overall oil temperature significantly.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
- cessna170bdriver
- Posts: 4063
- Joined: Mon Apr 22, 2002 5:13 pm
Re: Cold weather oil temps
I've heard this one ever since I bought my airplane. The story goes that Cessna cured an oil temp problem by just cooling the sensor. Well, it's just my humble opinion, but I believe this an old wives tale. I don't see how you can change the temperature of the sensor without changing the temperature of the moving oil it's immersed in.t7275tr wrote:Covering up the blast tubes that duct air to the oil screen does not really raise your oil temp. It only increases the indicated temp by raising the temp at the sensor in the screen. If you want to really scare yourself, leave the cover over over the blast tube and see what happens to your indicated oil temp on a 90 degree August day.
Miles
Miles
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
- Bruce Fenstermacher
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- Joined: Tue Apr 23, 2002 11:24 am
Miles I think the oil at the sensor is cooler but it doesn't accurately reflect the temperature of ALL the oil. An yes by it's nature the blast tube would cool the oil but not significantly.
Since the temperature readings we use in other seasons has the blast tube cooling that spot how would you compare a reading of 180 degrees i the summer with the blast tube against 180 degrees in the winter without the blast tube. In other words your changing the calibration of the measuring system. IMHO
My point all along is that I have not found it necessary to block the blast tubes to raise my oil temperature to 180 degrees at an OAT of 20F.
Since the temperature readings we use in other seasons has the blast tube cooling that spot how would you compare a reading of 180 degrees i the summer with the blast tube against 180 degrees in the winter without the blast tube. In other words your changing the calibration of the measuring system. IMHO
My point all along is that I have not found it necessary to block the blast tubes to raise my oil temperature to 180 degrees at an OAT of 20F.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com