Oil Cooler Opening on Aft Baffle

Hi All-

I am working on installing the oil cooler on the #4 cylinder aft baffle. I have read several posts on reinforcing the area to hopefully avoid any cracking. My question comes from a statement in the instructions. It says to mount the oil cooler as high as possible, but keep at least a half inch of clearance to the cowling. When I do this, the bottom of the oil cooler ends up about 5/8" below the level of the cylinder cooling fins. Should I cut the air hole in the baffle to stop at the level of the cooling fin on the cylinder, or make the cut to the bottom of the oil cooler. I am not sure if that will effect cooling on either the cylinder or the oil?

Peter,
Also pay attention to oil cooler bolt (middle right as seen from the back) by the engine mount. If you go too high it may meet the mount.

pmccoy said:

Hi All-

I am working on installing the oil cooler on the #4 cylinder aft baffle. I have read several posts on reinforcing the area to hopefully avoid any cracking. My question comes from a statement in the instructions. It says to mount the oil cooler as high as possible, but keep at least a half inch of clearance to the cowling. When I do this, the bottom of the oil cooler ends up about 5/8" below the level of the cylinder cooling fins. Should I cut the air hole in the baffle to stop at the level of the cooling fin on the cylinder, or make the cut to the bottom of the oil cooler. I am not sure if that will effect cooling on either the cylinder or the oil?

Click to expand...

Hi peter,

Im at the same stage as you, and last night asked myself the same Question.
I have been looking for the answer, and so far all I came up with is this web link.


http://www.jeffsrv-7a.com/ENGINE/06-03-08.htm

I hope someone will post more links/photos please.

Long ago, I faced the same issue. At first, I cut the hole high, with the bottom a half inch or so above the top of the cylinder fins. I had oil cooling problems for almost a year until I went ahead and extended the hole all the way down to the point where the fins are directly against the baffles. My oil temps went down by 20-30 degrees immediately and have been great ever since.

So that's what I'd recommend - cut the opening all the way down to the point where the fins meet the baffles.

I will add that this had little or no impact on the #4 CHT's which was a concern.

Other bracing ideas,....

This is just one man's version. First thing to do is set the baffle height using methods of your choice. The right corner is going to determine how how high you can set the cooler up. Where the bottom goes is just where it ends up but it should be well above the bottom of the baffle. See pix below.

Keeping it from shaking is also important. I ran a 3/8 SS tube flattened on both ends and bent accordingly to brace the rear baffle. It comes off the engine block to the baffle and note that I also reinforced the area it goes to as well.



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The following may be overkill :-( On the back side, I put a .032 plate over the whole cooler area and extends around the engine mount and ties into the lower block baffle bolt. Can send pictures by Em if you want them.



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It is absolutly rock solid in all directions. I also paid close attention to the blot spacers so that there was NO clamping distortion when they were tightened up. I also used larger washers on that side to spread the stress area. I "think" I also used sligthly larger washers under the flange as well and fit them with a grinder. Note area cut out to clear mount. I repositioned another bolt so that I still have 3 on that side.



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Not sure this won't move a stress crack someplace else but it's just what I did. Don't have enough hours to tell if it will work long term but for now it looks good.

Hope the pictures help!

Bill S
7a on the verge

I'm not sure if the others actually answered your question, but cut the hole to the size of the oil cooler. The oil cooler temperature will be much more limiting than the CHT's and you will have insufficient cooling for oil if you don't expose the entire surface of the cooler to inlet air. The bottom of the cutout will be somewhat below the top of the fins. You will also need to trim the upper outboard corner of the oil cooler doubler to get the cooler as high as practical. I think I ended up with the bottom of the cutout about 1.5" below the cylinder fins. The CHT's were still easy to balance with a small (about 3/4") air dam in front of cylinders 1 and 2.

Oil Cooler Opening and Placement of Oil Cooler

I am in South Louisiana and in terms of a hot environment, I can't imagine any hotter. Therefore I did several things to ensure cooler oil temperatures even if the outside air was 95 degrees with 95% humidity. I followed Dan Checkoway's lead and offset the oil cooler further back from the baffles. This removes the cooler from being next to the cylinder head. I used 1 in angle aluminum to offset the cooler back. Furthermore I purchased the Pacific Cooler, the larger and more dense cooler than Van's sells with the engine.
My angles further support the oil cooler and make this area stiffer. I had to remove part of the oil cooler so as not to hit the engine mout strut.

On a very hot humid day, my oil temps are in the 190 to 200 range. The highest temp is 205 and as soon as I lower the nose, the temps drop.
I can send photos if you are interested.

Steve Anderson
RV 7A 165 hours
Lafayette, La.