Bubblehead

Bubblehead

Well Known Member
My 4 new cylinders are doing great. CHTs are around 380 even in the hot weather, although at altitude and <75% power when I lean the engine they rise to about 410. My oil temperature is causing me some concern though. It goes up to 230 and I have to level off from climb and reduce power to 2200/22" and wait about 10 minutes to let the temp get down to 210.

Today I pulled the Vernatherm and will test it tonight to see if it "grows" to the right length at the right temperature. After I pulled it I looked over the oil cooler installation and hoses to see what else might be causing problems. I may have longer hoses than are necessary which may be causing or allowing air bubbles in the hoses that may be slowing flow that may be.... You get the picture.

Here's a picture looking from the left side of the airplane with the corner of the standard Vans cooler in the lower left. The braided line and the black line just below it are the cooler in and out.

Do you think the humps are causing problems? If I redo the hoses to eliminate the humps the oil cooler will be the high point of the system and I may just be moving any air from the hoses to the cooler. There is no way to vent the line anywhere so I am not sure how to be sure there are no air bubbles.

575548361_F4anq-M.jpg
 
Just a possibility but is the cooler outlet (top port) going to the correct point on the engine? The usual return is right next to the top left hand engine mount, but your oil return line seems to run to a different point. It might well be correct since it is difficult to see in the photo.
Doug
 
To answer your question, I don't think the routing of the hoses is a problem - humps or not.

One thing I can't tell from your picture is whether oil is flowing into the cooler at the bottom or not? Check and make sure the oil does flow in at the bottom of the cooler.
 
I just installed my oil cooler today. The first thing I noticed with your installation compared to mine is that the top hose of yours is coming out an an upwards angle, whereas mine is at a downward angle, which is how my plans showed it (RV-9A). That might be why the posters are wondering if you got your hoses correct. The next thing I noticed is that your cooler seems to be mounted lower than mine. For me, I had to trim the right flange down to just above the second mounting hole but it appears you only had to trim the upper corner to clear the engine mount. With the cooler mounted lower, there may be a little less cooling airflow.

I am hardly an expert at this. I probably wouldn't have noticed anything had I not just been working on this today.
 
I checked the Vernatherm tonight and it seemed to check out fine. It's length was:

3.760 at 90F (garage temp)
3.850 at 165
3.880 at 175
3.990 at 185
4.006 at 195

Doug and Kyle - I will double check that everything is going to the right place next time at the hanger. One thing that may make it look funny is this is a "Dual Mag" engine with the Bendix all-in-one mag so the connection points are a little different than the two Slick mag accessory case.

I dug up some other photos and none of them show it clearly but it looks like the hose with the braid on the outside is going to the lower attach point on the engine and the black hose is going to a fitting between the vacuum punp and the right top engine mount, just aft of the thermometer well.

Just to make sure I understand, the oil is supposed to flow from the engine into the bottom of the oil cooler and from the top of the oil cooler back to the engine? Gotta get those plans out again and check this out. I'm not sure that I see it makes a difference though.
 
Bubblehead said:
Just to make sure I understand, the oil is supposed to flow from the engine into the bottom of the oil cooler and from the top of the oil cooler back to the engine? Gotta get those plans out again and check this out. I'm not sure that I see it makes a difference though.
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Yes, in at the bottom out at the top - otherwise air will likely become trapped. This air will prevent some oil to flood the tubes, reducing the effectiveness of the cooler.
Doug
 
SMO - I looked at that yesterday. The diagram that shows oil in and oil out (Fig 5) is for a engine with separate mags. My engine has the dual mag. I think the oil to the cooler location is the same on both but the oil return to the engine goes into a different place. The only diagram in that document that shows my accessory case is Figure 3.

If that is true, then it looks like the lower hose on the cooler is the supply line from the engine, which is the correct orientation.

I've also looked through the Lyc overhaul manual and the parts manual for the engine without any success.
 
Oil Temp

John,

My hanger neighbor was having the same issue with the same set up as yours. He move the oil cooler back from the baffle by 1" and that took care of the problem. I was planing to come up to Dekalb yesterday but the 30+ knt cross wind at C09 was just a little to much.
 
Hi Pete. Good to hear from you. Good thing you did not come up because I was in Virginia Beach visiting one of my sons. I'm back in town Friday night so maybe we can meet up on Saturday?

I've heard of others moving the oil cooler back with great success. Does your hanger mate have any pictures? I've pulled a few pictures from posts here at VAF but the more pictures I see the easier the modification will be.

The oil cooler is old, and starting to crack on the flanges. I had intended to replace it but by the time I got through the cylinder replacement challenges it was April and I wanted to fly, not modify. I wish now I had taken the old cooler to a radiator repair shop to have it flushed or "boiled." I suspect I have some flow blockage in it too. They could probably do some repair to the flanges and the cooler would last fine until I'm ready to change it this winter.

I think I also want to shorten the hoses to reduce the pressure drop and reduce the hump in them.

I'm out of town all next week too so maybe I'll pull the cooler and have my wife drop it off at a radiator shop Monday for Friday pickup. I can reinstall and be flying again Saturday.

Anyone else out there have some unposted pictures of the oil cooler with a 1" spacer between it and the baffle?
 
pdecraene7a said:
John,

My hanger neighbor was having the same issue with the same set up as yours. He move the oil cooler back from the baffle by 1" and that took care of the problem. I was planing to come up to Dekalb yesterday but the 30+ knt cross wind at C09 was just a little to much.
Click to expand...

FWIW, both my 6A, and a friends 9A oil coolers from Van's are mounted directly to the back of the baffle. Temps yesterday, were around 90 F. at our airport level of 4200', and around 77 in cruise of 7500' msl. 9500' gave some air conditioning relief at 56 F. :)

Oil temps on both aircraft were running at close to 185 at we headed back to the airport at 5500'. I have an 0360, and he runs an 0320.

L.Adamson --- RV6A (flying)
 
Oil line routings checked

The oil line at the top of my cooler is going to this location on the engine. This is looking down from the top. That's the vacuum pump at the top of the photo and the tach drive location to the left. The tach cable is removed so you can see the connection.

581753165_ZhTZj-M.jpg


The oil line at the bottom of my oil cooler is going to this location. This view is from the right side of the plane, and you can see the oil filter. Just below this connection is the Vernatherm.

581753099_az34L-M.jpg


It looks like I have the connections backwards. I believe the connection by the tach drive is "oil to the cooler" and should go to the bottom of the oil cooler, and the other one is the oil return from the cooler which should be connected to the top of the oil cooler.

This is a dual-mag engine so the return is in a different place than engines with two seperate magnetos.

Does it really matter which side is which? I'll probably change it just to find out, but I'd really like some help from the wise people in the audience!
 
You want the oil coming in from the bottom to push any air bubbles out the top. Otherwise, you may have some voids and oil not in contact with all of the heat exchanging surfaces.
 
pdecraene7a said:
John,

My hanger neighbor was having the same issue with the same set up as yours. He move the oil cooler back from the baffle by 1" and that took care of the problem.
Click to expand...

I would not recommend moving the oil cooler back from the baffle. It creates a cantilever force on the baffle and is MUCH more likely to produce baffle cracks.

Get your oil lines set up the correct way (in at bottom of cooler, out at top). If that doesn't work start sealing up any leaks in the baffles. If you can't maintain reasonable positive pressure differential above the engine then less air will go through the oil cooler. There's higher resistance for air travelling through the oil cooler than through the cylinder head fins.
 
I started changing the lines around this afternoon, but every project with my -8 is a can of worms. Of course one line changed over fine and the other one is just barely held out of position by something else in this case, the upper right Lord pad. I don't have a 45 degree -8 fitting to make things right so am making an 1/8" spacer to move the cooler a little bit back, which will let the upper line connect properly.

Captain Avgas - I understand what you're saying and agree, but many people have moved it back. Many have put a brace between one of the crankcase bolts and the oil cooler to take the load. I might do that or try to build a flexible support from the aft side of the cooler to the engine mount. I realize the engine and engine mount do not move together because of the Lord pads between them, but perhaps I can design something to allow that but support the cooler

To all - Obviously to make and install the spacer I had to take the oil cooler out. I bought this RV already licensed and flying and was not sure what oil cooler it had. While it was off I copied this off the name plate.

Harrison Radiator Division
General Motors
Model# AP09AV06-01
Part# 8529245
Serial# 73E-874
Customer No. 455-192

I did a quick search on the internet and this model was used on a the Maule MS-235C and M6-235 (both came stock with 235 hp IO-540s) and the Piper PA-28-236 and PA-32-301 among others. It's equivalent to the Nigara 200003A and Aero Classics 9 row 8000074. I'm not sure if it came from Vans or somewhere else.

I'll finish the spacer tonight and install and test tomorrow.
 
L.Adamson said:
FWIW, both my 6A, and a friends 9A oil coolers from Van's are mounted directly to the back of the baffle. Temps yesterday, were around 90 F. at our airport level of 4200', and around 77 in cruise of 7500' msl. 9500' gave some air conditioning relief at 56 F. :)

Oil temps on both aircraft were running at close to 185 at we headed back to the airport at 5500'. I have an 0360, and he runs an 0320.

L.Adamson --- RV6A (flying)
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Larry - do you know what model oil cooler you and your friend have?
 
Bubblehead said:
I understand what you're saying and agree, but many people have moved it back.
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Yep, and many have developed cracks. Dan Checkoway's experience is probably typical (unfortunately his website has been removed).

In fact most set-ups with the cooler mounted on the baffles as per Vans standard drawings develop cracks. And offsetting the cooler just exacerbates the problem. And I certainly wouldn't dream of supporting the cooler off the engine mount.

Anyway, don't say I didn't warn you. ;)
 
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Bubblehead said:
It looks like I have the connections backwards. I believe the connection by the tach drive is "oil to the cooler" and should go to the bottom of the oil cooler, and the other one is the oil return from the cooler which should be connected to the top of the oil cooler.

This is a dual-mag engine so the return is in a different place than engines with two seperate magnetos.

Does it really matter which side is which? I'll probably change it just to find out, but I'd really like some help from the wise people in the audience!
Click to expand...

Perhaps a phone call to Lycoming support or any of the major engine builders (say Aerosport for example) would elict the correct information. Don't rest until you are 100% certain the plumbing is correct. Better safe than sorry!

The Lyc. manuals I have simply do not cover your engine type nor the spin on oil filter adapter.

From my reading - it does matter which side is which.

Doug Gray
 
By George I think he's got it!

Last night I dug through every Lyc manual I could find for any Dual Mag equipped engine info. I had to put bits and pieces together from multiple sources but it looked like hoses are going to the right places on the engine but are reversed on the cooler. I'm not sure why that would matter except when an air bubble is considered.
This morning I was at the hanger by 6 am and reversed the lines. To get a connection without putting extra stress on fittings I had to modify the oil cooler mount so the inbd side was 3/16" farther aft. That angled the upper fitting just right so the return hose would clear the motor mount.
While I am not overly proud of the modification (safe, secure, but ugly - kind of like some of the girls I used to date) the 1 hour test flight revealed much lower temps. OAT is only 70 today, but I climbed at 120 kts to 7500' and oil only got up to 220F.
At cruise my CHTs were around 350 and oil dropped to 190. When I reduced power and leaned it out CHTs were around 400 and oil was 230.
This is much better than I had been experiencing. When I flew back to IL from TX two weeks ago I saw 240F oil temp within minutes of takeoff with 80 OAT.
I don't know if it is because of the shim moving the cooler back a little or the swap of the oil lines, but either way thing are better. I am concerned about the baffle cracking, but the builder added a thin sheet metal doubler over this entire part of the baffle so I think it will hold up. The doubler is riveted to the aluminum so it is stiffer, and the steel will be much less prone to fatigue cracks.
Next step is to make a nice spacer/shim and maybe shorten the hoses slightly to improve the geometry even more.
My thanks to everyone who chimed in on the issue. This forum is of great value to me. It seems like every week, usually every day, I learn something new and important.
 
Bubblehead said:
Larry - do you know what model oil cooler you and your friend have?
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They are both, what Van's advertises as "Traditional Harrison/Stewart Warner Style Oil Coolers"..........which means Niagra's. Both are mounted
behind cylinder #4 on the real baffle. I looked at my cockpit pics from last Sept. to now. The highest oil temp is 195 F. Mine is a 6A with a Lyc 360, and the other plane is a 9A with a Superior O320. His temps are about the same as mine. In the winter, I have to put tape over the inlet. For next winter, we'll have adjustable exit doors.

L.Adamson
 
Thanks for the info, Larry. Just trying to have as good of knowledge of oil coolers as I can. That is the same oil cooler as I am using. Temps got a lot better after I swapped the lines on the cooler so oil from the engine goes in the bottom of the cooler.
 
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