Oil temperature question

[Colorado-Cub]

I reused the cap part of the vernatherm. I just removed the spring clip and the vernatherm mechanism.

I was hoping you would say that. The plug is like $130 new but I didn't want to tread new ground...

 

[Schwarz]

Hello everyone,
I've read thru this thread and have some questions. I have a O-360 in an experimental backcountry super cub that is running high oil temps, 230-235 or higher with OAT 100*f. I have checked the temp gauge with a temp gun after flight, I haven't checked it with sending unit heated in oil but seems accurate according to readings on the heat gun. It is a steady temperature increase at any power setting straight and level, won't cool off when I reduce RPM to 2100 or so. CHTs are around 370-380. Cylinder compressions were all 78-79 at last inspection in June. I just changed the oil and checked the filter, no metal found. I removed the vernatherm and tested it in heated oil, it didn't start to move until around 215-220 so I replaced it. The old one does not have a complete 360 degree witness mark and the seat looks wrong.

Does anyone have a copy of Lycoming service instruction 1316A? Will this create a high oil temp situation as described? Here are some pictures of how oil cooler is mounted.

After I changed the vernatherm I flew for about 30 minutes after a brief rain shower here in south Texas, OATs in the low 80s and oil temps around 220. Baffling seems good, left side seal,

Right side seal,

The oil cooler has a 3" hose running to it, will a 4" hose help? I have the material to put 4" SCAT to the cooler but the heating problem wasn't noticeable last summer, probably because I was in NE PA, didn't get as hot up there. I would like to address the vernatherm seat after I get a copy of the 1316A. Is this set up wrong for the heat of Texas or should it be sufficient if everything is working correctly? I know its a lot of questions, but any help is appreciated,

thanks in advance,

 

[Rice farmer]

Others smarter than me will reply but as addressed previously it seems you would want to dispose of the vernatherm as I have done on my 160 cub and on our C 195. Mag timing helped on mine also overhauling my low time slick mags helped.

 

[DENNY]

CHT's of 370-380 is hot. You need better engine cooling to solve your problem. Seaplane lip, bigger cheeks, check mag timing, and carb is what you need to look at. I would also go to viscosity valve for the oil.
DENNY

 

[skywagon8a]

CHT's of 370-380 is hot. You need better engine cooling to solve your problem. DENNY

I disagree Denny, with an ambient temperature of 100*, CHTs 370-380* is good cooling.

A 4" hose giving more volume of air through the cooler may help. And the seaplane lip is also a good recommendation.

 

[PerryB]

The 3" hose is probably marginal in terms of airflow volume. A 4" will flow a LOT more air, like about 70% more. Also a small baffle around the cylinder right in front of the intake will keep the hot air moving down and around the cylinder, and not into the intake. Look at the last pic in post#72. Try the baffle first, it's a lot easier. The Vernatherm is not helping obviously. Its allowing some oil to bypass the cooler. It looks to be a minor seat repair issue and not very serious, but certainly a contributing factor.

 

[Steve Pierce]

First thing I would do would be to get a manometer and see what kind of pressure differential on either side of the oil cooler. It is all about air flow and without modifying anything you can see what you have going on. https://www.amazon.com/Digital-Manometer-Pressure-Differential-Hti-Xintai/dp/B07KQVWFMK

Tom and I spent many hours troubleshooting a similar issue and documented it here.
https://www.supercub.org/forum/showthread.php?46845-High-Oil-Temperature-Experience

 

[RaisedByWolves]

Wes, you didn’t have this problem when you were up north. Just saying..
bowman is next weekend. No fog right?


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[Schwarz]

Thanks everybody, I've ordered the manometer and will start checking airflow Monday. I would also like to review the

service instruction 1316A, where is the best place to get a copy?

Thanks again,
​

 

[Schwarz]

Tom I’ve whined more than once about the heat down here, 18 months up there and I appreciate your summers, but still a fan of a Texas winter, ;-)
Probably won’t make Bowman or the WAD this year sad to say, unless something different happens pretty quick. Melissa and I would love to see y’all again!!


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[Schwarz]

PS.... I’m still trying to find South Carolina.


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[DENNY]

Skywagon8
He has the 370-380 temps at 2,100 RPM. I could see that happening at 2,500 RPM, but at 2100 he should be a lot lower even with the high ambient temps. I am not a fan of silicone baffling but his looks good with witness marks on the cowl doors.
DENNY

 

[skywagon8a]

Denny, I read his post as meaning the oil temperature started down when the rpm dropped below 2100 and that the CHTs did not exceed 370-390 at all power settings.

 

[DENNY]

Skywagon8
That would sound a lot better.

Schwarz
I don't see a lot of CHT probes how are you getting that reading. Is that just one cylinder?
DENNY

 

[stewartb]

With that oil cooler installation you could add a pilot controlled scoop on the top cowl and force more air through the cooler without stealing any air from the top deck. If it was mine? I'd hang a 9 vein cooler on the rear baffle and lose the blast duct or move the cooler to the nose.

Those CHTs are great in my opinion. Below 400* in 100* ambient is an achievement. Part of that success may be because there isn't enough air going to the oil cooler. Open up the cooler flow and you may see your CHTs rise.

 

[Schwarz]

Denny I am getting that reading on one cylinder, not a fan and I have been contemplating getting a better engine monitor but I have checked the readings with my temp gun and they are pretty accurate. Also to clarify, the oil temp will not come down at low power settings, the CHTs will a little bit. Even when taxing back to the hangar oil temps won't cool. I shutdown and immediately shoot the engine to see what the temps are, last time OAT was 106, all CHTs were with in 10 degrees or so of each other and oil temp shooting 235 around filter housing where the temp prob is located. Here is a pic of my gauge setup,

After reading through the thread Steve P posted the link to I'm going to check my airflow through the cowling and see what I need to do to repair the vernatherm seat....or move up north. :lol:[SUB][/SUB]

 

[stewartb]

A 3" blast tube provides 7.065 sq in of area. Changing to 4" would provide 12.56 sq in. My 9 vein Niagara coolers have 22 sq in of cooling area each. The blast tube arrangement is limiting your oil cooling potential.

 

[Schwarz]

A 3" blast tube provides 7.065 sq in of area. Changing to 4" would provide 12.56 sq in. My 9 vein Niagara coolers have 22 sq in of cooling area each. The blast tube arrangement is limiting your oil cooling potential.​

I have the stuff I need to change it to 4", do you have any idea what CFM of air is going through a 4" tube at cruise if airflow through the cowling is good??

 

[stewartb]

No idea, but it can't match the flow through a fully exposed cooler on the rear baffle. But you can duct air from other places than just the top cowl. That would be a good place to start without impacting your CHTs.

 

[CamTom12]

No idea, but it can't match the flow through a fully exposed cooler on the rear baffle. But you can duct air from other places than just the top cowl. That would be a good place to start without impacting your CHTs.

There may not be room back there between the baffles and the engine mount for a fully exposed oil cooler. That’s the big problem I had with mine. I don’t think having the oil cooler flush against the cylinder does any good.

I’d 100% install your 4” SCAT. That’s what’s feeding my 8406R and I have to block the inlet to warm up to 180 degree oil temps now. I’d do this no matter what - you live in the South now .

I also think your upper to lower cowl pressure differential will turn out to be low. From the pictures I’d be willing to bet your upper cowl pressure difference to static pressure will be high, and that your lower cowl will have fairly high pressure as well.

If that’s the case, I’d fabricate a seaplane lip on the forward edge of your lower cowl opening. You need to create a low pressure area below the lower cowl opening so it can help evacuate the lower cowling.

 

[stewartb]

Having never seen a section view of an oil cooler's cooling core, is there a reduction in efficiency when the cooler is laid horizontal rather than the vertical installations 99.9% of us use?

 

[skywagon8a]

Having never seen a section view of an oil cooler's cooling core, is there a reduction in efficiency when the cooler is laid horizontal rather than the vertical installations 99.9% of us use?

The important thing to consider is to whether there can be some blockage trapping air in the cooler which would effectively reduce the available cooling capacity. It's best to place the inlet at the bottom and the outlet at the top in order for any air to be purged.

 

[CamTom12]

The important thing to consider is to whether there can be some blockage trapping air in the cooler which would effectively reduce the available cooling capacity. It's best to place the inlet at the bottom and the outlet at the top in order for any air to be purged.

True. I mounted mine at a slight angle, with the outlet on the top.

 

[stewartb]

The important thing to consider is to whether there can be some blockage trapping air in the cooler which would effectively reduce the available cooling capacity. It's best to place the inlet at the bottom and the outlet at the top in order for any air to be purged.

My coolers are 3-1/2" thick. I believe oil is spread across the full width dispersing heat through all the webs as it travels through the cooler from top to bottom. Laying on it's side I wonder how much of that width (now height) is filled with oil. If gravity holds the oil on the bottom half of the veins the cooler is losing much of it's capacity to cool the oil. I don't know if that's how they work but if I had the setup in the pics? I'd be asking a cooler manufacturer to hear what they had to say.

 

[bob turner]

I might have missed a comment on this: all those rubber seals stapled to the aluminum baffles go up and forward, right? That can make a startling difference in oil temp.

 

[Gordon Misch]

My coolers are 3-1/2" thick. I believe oil is spread across the full width dispersing heat through all the webs as it travels through the cooler from top to bottom. Laying on it's side I wonder how much of that width (now height) is filled with oil. If gravity holds the oil on the bottom half of the veins the cooler is losing much of it's capacity to cool the oil. I don't know if that's how they work but if I had the setup in the pics? I'd be asking a cooler manufacturer to hear what they had to say.

Interesting point that I hadn't thought of. Depends on the flow rate, among other potential parameters I'm not sure of. If one were to mount the cooler such that the inlet is on the bottom, and the discharge is on the top, the cooler would be assured to be full. I think you have a valuable question there.

Edit: Also, the inlet and outlet ports are in the centers of the ends of the cooler. Seems like when mounted horizontally it would be pretty easy for air to be trapped on the top if the oil flow is insufficient to purge of all the passages.

 

[DENNY]

Air in the oil cooler is a definite possibility (I did not notice it) and the cheapest thing I can think of to fix. Disconnect the highest line and cooler from mount stand cooler on edge so all air will come out (shake and tap) fill top line with oil and reconnect.
DENNY

 

[G44]

Your symptoms still sound to me like sludge in the engine plugged up the new oil cooler. First flight was good and it got blocked with sludge so subsequent flights have high oil temperature. I would remove the cooler and backflush it with solvent and see what comes out. If the oil cooler worked on the first flight, it should have continued to work, unless the flow of oil or air was blocked. From what I read, the air flow is not blocked, so it only leaves a blocked oil flow as the culprit.

^^^^^^^ This ^^^^^^^

 

[C-FIJK]

Hello Like I had mentioned above take the oil cooler and move it to the front and all your problems will be solved .

Hello everyone,
I've read thru this thread and have some questions. I have a O-360 in an experimental backcountry super cub that is running high oil temps, 230-235 or higher with OAT 100*f. I have checked the temp gauge with a temp gun after flight, I haven't checked it with sending unit heated in oil but seems accurate according to readings on the heat gun. It is a steady temperature increase at any power setting straight and level, won't cool off when I reduce RPM to 2100 or so. CHTs are around 370-380. Cylinder compressions were all 78-79 at last inspection in June. I just changed the oil and checked the filter, no metal found. I removed the vernatherm and tested it in heated oil, it didn't start to move until around 215-220 so I replaced it. The old one does not have a complete 360 degree witness mark and the seat looks wrong.

Does anyone have a copy of Lycoming service instruction 1316A? Will this create a high oil temp situation as described? Here are some pictures of how oil cooler is mounted.

After I changed the vernatherm I flew for about 30 minutes after a brief rain shower here in south Texas, OATs in the low 80s and oil temps around 220. Baffling seems good, left side seal,

Right side seal,

The oil cooler has a 3" hose running to it, will a 4" hose help? I have the material to put 4" SCAT to the cooler but the heating problem wasn't noticeable last summer, probably because I was in NE PA, didn't get as hot up there. I would like to address the vernatherm seat after I get a copy of the 1316A. Is this set up wrong for the heat of Texas or should it be sufficient if everything is working correctly? I know its a lot of questions, but any help is appreciated,

thanks in advance,

 

[don d]

What is that motor mount nut torqued to?