hot oil

I have read everything I can find on the forum about high oil temperatures on the RV8. I have tried every suggestion here except putting louvers in the cowl. I really don't want to start cutting the cowl. I need to find my problem. There are too many RV8s flying without marginal oil temperatures. Titan IO360 with 9 to 1 pistons (no squirters). I bought the "big" oil cooler and installed it on the baffle behind #4. Moved it to the firewall with 4" hose. Outside air temperature around 90 degrees F. 24 squared at 2000 MSL will eventually get the oil up to 225 degrees F. I can very slowly climb to altitude and it will settle around 205 degrees F (10 minutes). Oil flow has be checked, hoses of been checked, the sensor has been replaced and the new one has been checked, the gauge (Dynon) has been checked, the vernatherm has been removed twice and checked. The baffles have been super sealed and are tight. CHTs have never seen 400 degrees F....never seen the highest one over380 degrees F. EGTs no higher than 1255 degrees F at take off power. What can the problem be?

Are you using -6 or -8 oil cooler hoses?

DEWATSON said:

What can the problem be?

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Not saying that it is necessarily the cause of your probelem, but one significant variable between one engine and another can be the amount of piston ring blow-by.

If you didn't get good ring break in, it can allow enough hot gasses blow-by to cause a significant increase in oil temp.

The difficulty in diagnosing this is that it won't neccesarily result I high oil usage or low readings when you do a compression check.

How was oil flow checked?
What exactly was flow checked?
Its not unusual to have a kink in the oil line that the fire sleeve hides. Walk your fingers down the lines and verify you have no kinks. You can feel a kink with your fingers. I suspect you dont given you have moved the cooler, changed the cooler, and probably had to change lines. But worth looking at. It is very unlikely that cutting any amount of cowl or louvers will help your problem given your other good data. Ill see if I cant get Bobby from Titan to jump in.

I bought the engine from America's Aircraft Engines (Richard Fowler) and I claim I have good ring seating. I have to put a quart in every 7 hours or so. The cooler lines are 8s with no kinks. I have moved them around just to try something different. The flow was not checked with oil....I did it with my breath. Effortless blowing through the cooler, effortless blowing through the hoses and effortless blowing through the hoses and cooler with them hooked together. I've always battled high temps by doing slow climbs and at altitude it will stay around 200. Lately it has gotten much worse. I just got back from a .6 hour flight at 2000 feet MSL at daybreak and I saw 227 degrees F before landing. I've checked everything but I must be overlooking the obvious. I think I'll order a new vernatherm.

Take a look at this link:
http://www.vansairforce.com/community/showthread.php?t=103676

Walt,

This is something that I was not aware of. I'll go investigate right now!! Thanks (fingers crossed).

Hot Oil Problems......ideas

DEWATSON said:

I have read everything I can find on the forum about high oil temperatures on the RV8. What can the problem be?

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DeWatson,

There are two things we have done to our R&D RV8 to control oil temp. One was putting lid on Vans air-box baffle system and the other was to move the cooler back a bit from the air box and turn it slightly. I will take some photos of my installation and this might give you some ideas....

You are always welcome to email us at [email protected] and someone will try an help you further with your installation.

I just took the oil filter housing off the back of the engine and peaked into the vernatherm cavity. The gaskets are correct and the passages are wide open. I also took the hose nipples out of the engine and peaked into those cavities and they are wide open and super clean. I drained the oil from the oil cooler lines and blew through them with the hoses connected to the cooler. I can blow through them with no trouble at all. I wonder if the vernatherm is long enough and isn't sealing properly. Someone made a statement yesterday that the constant speed propeller will make the vernatherm "dance" on the seat if it is a bit too short. Is there anything to that statement?

Relentless....please take photos and send them to me or post them here. I started to try to make an offset last year, but there isn't enough room between my engine mount and cowling to make the angle work. I would really like to see what you've done. Thanks. [email protected]

I would guess the cooler

I'd wonder about the cooler. Either the quality of the unit or the cold air flow it is actually receiving. Your baffling is obviously working well with the low CHT's, but is the cooler actually getting cold air flow through it? I had anticipated a problem with oil cooling on my hybrid motor IO-320 with 9:1 and squirters, so I had a friend fabricate a dedicated fiberglass "scoop" on top of the engine, back to the oil cooler that is mounted behind the motor on a 45 degree angle from the firewall. the cooler is the 13 fin SW (I've heard others complain that different model/less expensive coolers can perform quite differently/not well). Air flows straight through the cooler down the back of the firewall and out

My CHT's run around 330 and oil temp 180-190...colder (160-170) in winter. If nothing else works, you might try this, but start with the top quality oil cooler. good luck!!
Ron
RV-4

Post them here please!

I need to correct myself.......I reassembled the oil filter housing on the bench and I've found that I do have the gasket that half covers the oil passage from the vernatherm cavity. Others say this gasket is incorrect and installing the correct gasket should fix my problem. One poster above said that the gasket won't make a difference. Those that have changed the gasket and seen improvements; how much improvement have you seen? BTW, I have the larger SW oil cooler. There is a 4 inch SCAT tube from the baffle behind number 4 cylinder. The cooler is mounted flat (face down) on the firewall with the nipples forward. Will the flat position of the cooler make a difference?

I had originally installed my oil cooler on the RV8 the way you described
in a horizontal position with a 4" SCAT supplying air taken from the rear baffle
on the left side. I fabricated all sorts of ducts and deflectors hoping to see improvement in cooling. Everything else was also checked all without any measurable improvements.
I reluctantly moved the oil cooler to the rear of the left baffle and immediately
had oil temps drop 30 degrees. From then on oil temps were no longer a concern. The baffling will need to be beefed up and the cooler braced for additional support.
I remember I had about 25hrs before changing the position and I was able to use the same hoses.
Hope that helps.

DEWATSON said:

Will the flat position of the cooler make a difference?

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Actually yes. Its an improvement. Getting the heat pointed down helps lower the overall FW heat soak into the cockpit. From an oil cooling point of view, there is no difference.

N427EF said:

I had originally installed my oil cooler on the RV8 the way you described
in a horizontal position with a 4" SCAT supplying air taken from the rear baffle
on the left side. I fabricated all sorts of ducts and deflectors hoping to see improvement in cooling. Everything else was also checked all without any measurable improvements.
I reluctantly moved the oil cooler to the rear of the left baffle and immediately
had oil temps drop 30 degrees. From then on oil temps were no longer a concern. The baffling will need to be beefed up and the cooler braced for additional support.
I remember I had about 25hrs before changing the position and I was able to use the same hoses.
Hope that helps.

Click to expand...

This is due to the much larger cooling sq inches allowed on a rear baffle mounted cooler.

Kahuna said:

This is due to the much larger cooling sq inches allowed on a rear baffle mounted cooler.

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Not to challenge, but to understand . . . My little cooler for the 360 w/o squirters has about the same area (flow area that is) as the standard vans cooler. It is the same flow area as 4" diameter.

Bob Mills had knows a builder (multiple offender) that uses 2 - 2" scat hoses to this cooler and says it cools just fine. He is down in Nevada.

The whole issue of the firewall vs baffle location as a simple cure or curse is not well explained nor absolute.

Sorry, this too much diversion from the OP. I will begin another thread with data when I overheat.