Oil temp problems

[MarkW]

Well I have always had higher oil temps than i would like but since I fly high and LOP alot it is never an issue. Low and slow is also not a problem.
Seems like the last oil change it got worse. Maybe it is just summer and not a new thing. Baffles are good and CHT are about 350 - 360 in fast cruise.
However if I don't run LOP peak oil temps will go to 230.
I have the standard Van's 20002A oil cooler mounted on the firewall with 3" SCAT. I don't have problems with climb but high power cruise.
I can climb to 8500' on a hot day and just start to see 200-210 but after another 5 minutes of cruise it can continue to climb.
I assume one of three problems.
Low airflow
hot air entering cooler
low oil flow i.e. bad or poorly seated vernatherm

I say hot air entering the cooler as a problem because my 3" baffle connection is very low and about halfway behind #4.
This weekend I checked air temps entering and leaving the cooler.
75 degree OA
85 degree oil cooler entering air
200 degree leaving air
209 degree oil temp.

These numbers lead me to believe position of my intake is fine. Only picking up 10 degrees over the cylinders.

I don't think my numbers help me with understanding low oil flow or low airflow.

My next step may be to pull the VT and check operation and seating.
It is a 340 hr. ECI Titan IO-320
a 320 doesn't make enough HP for the 20002a to be a capacity problem.
I may need to measure the oil line temp in and out next flight.
Any thoughts?

[tracy]

Not sure 210 is necessarily bad. Mine was at 180 and I blocked 3/4 of it off to get 205 to 220 degrees, however, I would not like seeing 230. I think the upper limit on vt is 220.

[tracy]

Always had good clean tear downs using this method. Never any corrosion issues as the hotter engine keeps out moisture.

http://generalaviationnews.com/2011/...l-temperature/

[DanH]

Originally Posted by MarkW

Any thoughts?

Thinking about things that may have changed....if it really has gotten warmer, do you also see any sign of increased blow-by?

A 10 degree rise, OAT to cooler inlet, is ballpark with my own measurements. I've measured as much as 17F.

A 200F outlet temperature seems a bit high. I'm not saying it's wrong, just that I've never recorded an air outlet temperature that close to oil temperature.

Velocity, area, and density would tell you mass flow.

If you measure oil temperature in and out, and mass flow, you'll be my new hero

[MarkW]

Hey Dan,
The oil is now about 25 hours and still very clean and no consumption.
I have eliminated blow-by. Also changed filter only after about 10 hours to check for metal thinking that a bad main bearing would get things a little hotter. (fishing)
I figure 200 is a bit warm but with 209 oil temp I figured maybe not.
If I remember correctly the oil temps are measured after the cooler so I assumed cooler might have been 220-240 so 200 out air seemed OK. (just guessing here)
Maybe the outlet air temp of 200 means low mass airflow and hot cooler.
I guess next is measuring oil in/out temps.
Have you measured these? What should I expect for a delta?
I might be too lazy to set up a manometer. Then maybe not I have a few.

[DanH]

Originally Posted by MarkW

Hey Dan,
The oil is now about 25 hours and still very clean and no consumption.
I have eliminated blow-by.

Agree

Maybe the outlet air temp of 200 means low mass airflow and hot cooler.

Seems reasonable. I have varied mass flow through the cooling system at large by varying TAS, and cowl outlet temperature drops as mass flow rises:

TAS....... Exit Temp
knots..... F
133.7..... 228
154.5..... 221
170.6..... 221
191.9..... 209

I guess next is measuring oil in/out temps. Have you measured these? What should I expect for a delta?

I have not measured mine. Randy Stuart posted this last year:

I run a temp sensor at two points. One in the normal oil cooler out, on the filter adapter, and one near the bottom of the oil sump just as the oil moves up to the pump. The differential is typically 30 F average, give or take 5 F as the oil warms up or cools down.

I might be too lazy to set up a manometer.

For velocity? Need a pitot-static in the duct. Area is at the plane of the static port.

[lr172]

Originally Posted by tracy

Not sure 210 is necessarily bad. Mine was at 180 and I blocked 3/4 of it off to get 205 to 220 degrees, however, I would not like seeing 230. I think the upper limit on vt is 220.

If you look at Dan's post above, you'll see that the oil in the pan is running about 30* hotter than the reading post-cooler. While I agree that 220 is a good temp to run, that only applies in the auto world, where they measure temp in the pan. If your lycoming is reading 180, the oil in the pan is presumed to be 220. If you are running 220 post-cooler, the oil in your pan is probably 250. Thats starting to bump up on the danger zone and your oil will oxidize much faster at that temparture.

This, I believe, is why lycoming recommends 180.

Larry

[MarkW]

Originally Posted by DanH

For velocity? Need a pitot-static in the duct. Area is at the plane of the static port.

http://www.niagaraairparts.com/20002...ifications.pdf

With this info seems like I only need static delta.
This will give me airflow in lbs/min. and using a psychometric chart I can get ft3/lbs with db and wb.
Wallah CFM and Heat Rejection.
Now what. I guess if I fall in the middle of the chart for Heat Rejection then I am good?
Do we have info that tells us how much heat rejection we need with a IO-320 @ 85% power?