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Baffles, aft baffle mounted oil cooler, and reinforcements...

Brantel

Brantel

Well Known Member
It seems that the newer baffle design is no more immune to cracks on the aft rear baffle when the oil cooler is mounted there than the old one...

Anyone not flying yet, do yourself a favor and beef this area up before flying!!!

I was naive and built mine per plans thinking the new brace design might solve the problem....wrong! Within 25 hrs I started seeing cracks in the corner. My prop has been dynamically balanced and the engine runs smooth. I have kept a close eye on the issue and it is soon to be repaired. I just purchased the $60+ worth of replacement parts in order to rebuild the aft rear baffle.

I plan to beef this area up greatly and add an angle brace.

If you have good ideas for beef up that you would like to share with me and others to come, please share them with us....

After contacting Van's about the fact that their baffle kit design is almost guaranteed to fail if built per the plans, the reply was something like we know it stinks, do the best you can with it, hopefully you will come up with a solution that will work for you, it is not our problem....not the best answer!!!
 
I have never mounted my oil coolers on the baffles. If you have room, mount it on the Firewall. I have managed to do that on my 6, 7A, and of course the 10. No problems, with lots of hours. I also believe that mounting them on the baffles provides an extra source of heat which the cooler needs to reject.

Vic
 
Vic,

Could you post a picture or two of your installation.......that's what I'm working on now. Thanks.

David Watson
49FD
 
Brantel, this has work well for me...



The picture should make is clear.
I use a piece of .063 angle and AN3 bolt.
I have seen this same fix going to the left side baffle instead of the engine.

Kent
 
Thanks Kent,

I have seen your brace before and plan to do something similar or the same.

Thanks!!!
 
add chromoly angle

Mine cracked at 100 hours. I added a piece of 3/4 x 3/4 4130 .032 chromoly angle on the outside where it cracked and no problems in the 600 hours since. One side of the angle runs forward towards the cylinder head, and the other side runs outboard.

Look at Randy Lervold's oil cooler plenum here.

http://www.romeolima.com/RV3works/FWF/firewallforward.html

Originally I had .032 alum. angle where Randy has 1/8' alum. angle on the forward side of the outboard edge of the plenum. When my .032 alum. angle piece cracked, I replaced it with .032 chromoly which resolved the problem. It looks like Randy used 1/8" 3/4 alu. angle there from the get-go to avoid the cracking issue. Either will work.

The plenum works well. My CHT's are always below 300 degrees in cruise, and I have to reduce the opening to the oil cooler in the winter to get 180 degree oil temps. I used a fly cutter to cut two holes in the backside of the baffle above the cylinders to let air into the plenum, and riveted a platenut between the holes on the oil cooler side. One hole is larger than the other. I can cover either or both with one or the other piece of alum. sheet to vary air flow and therefore the oil temp for Papa Bear, Momma Bear or Baby Bear settings. In Oregon winters, covering the larger hole works juusst right. Or you can mount the fancy shutter Van's sells in front of the cooler like Randy did.
 
It works

Brantel said:
Thanks Kent,

I have seen your brace before and plan to do something similar or the same.

Thanks!!!
Click to expand...

Cruise the posts and you will find many similar ways. I used steel tubing and formed tabs on the end. 300 plus hours, solid as a rock.
 
Reinforced on inside and outside

Hi Brian,

Here's my attempt...

Thanks to your advanced warning I have recently had a go at reinforcing that corner of my baffles. I made my own larger instrument panel so I canibalised the original panel and used the bottom flange to make a pair of .063" bent angle reinforcements. One reinforcement has gone on the outside of the Cylinder 4 Baffle as I have seen done by others. The other reinforcement has gone on the inside and replaced the FF-713 spacer. The FF-713 substitute is the part on the far right in the photo below. It has a somewhat complex shape to avoid interference with the cylinder head at the bottom and the CB-705B Oil Cooler Brace at the top. I also left it longer at the bottom as I'm going to use this to support the Alternate Air Cable.

2hs21oy.jpg


In the photo below the three open rivet holes in the top right are where the Oil Cooler Brace will attach.

51d25i.jpg


nycj0o.jpg


Besides the reinforced side baffle, I am installing the Oil Cooler shutter. I am using the original FF-709 doubler as a spacer behind the shutter (to stop the shutter binding on the fins of the Cooler) and have made a substitute flat FF-709 to rivet to the Cylinder 4 Aft Baffle.

All this should make for a hopefully much stronger back corner. I am yet to investigate installing some sort of cross-member to triangulate off one of the central engine case bolts.

Obviously, this is not flying yet so no experience of how it will stand up to the real world. Hope this may be of some use. I considered and rejected FW mounting the oil cooler, regarding my approach above less hassle.
 
I still think you need the brace

shuttle said:
Hi Brian,

Here's my attempt...

Thanks to your advanced warning I have recently had a go at reinforcing that corner of my baffles. I made my own larger instrument panel so I canibalised the original panel and used the bottom flange to make a pair of .063" bent angle reinforcements. One reinforcement has gone on the outside of the Cylinder 4 Baffle as I have seen done by others. The other reinforcement has gone on the inside and replaced the FF-713 spacer. The FF-713 substitute is the part on the far right in the photo below. It has a somewhat complex shape to avoid interference with the cylinder head at the bottom and the CB-705B Oil Cooler Brace at the top. I also left it longer at the bottom as I'm going to use this to support the Alternate Air Cable.

2hs21oy.jpg


In the photo below the three open rivet holes in the top right are where the Oil Cooler Brace will attach.

51d25i.jpg


nycj0o.jpg


Besides the reinforced side baffle, I am installing the Oil Cooler shutter. I am using the original FF-709 doubler as a spacer behind the shutter (to stop the shutter binding on the fins of the Cooler) and have made a substitute flat FF-709 to rivet to the Cylinder 4 Aft Baffle.

All this should make for a hopefully much stronger back corner. I am yet to investigate installing some sort of cross-member to triangulate off one of the central engine case bolts.

Obviously, this is not flying yet so no experience of how it will stand up to the real world. Hope this may be of some use. I considered and rejected FW mounting the oil cooler, regarding my approach above less hassle.
Click to expand...

I did reinforce the corner as you have done, but I believe the brace is what keeps that corner stable. I did both. Maybe over kill, but the brace is super simple to build and makes that corner solid as a rock.
 
Hi JonJay,

Thanks. Yes, I will almost certainly do both too. I've seen some folks attach the brace to the Aft Baffle quite high up. Personally, if I can, I would like to attach the brace to one of the two inboard Oil Cooler Mounting Bolts. The challenge I foresee will be finding a straight line route from that bolt past the pushrods tubes and injector fuel lines to a suitable case bolt.
 
Based on a bunch of old threads, and in addition to beefing up the outside corner with an additional piece of angle, this is what I did on the inside. Haven't flown yet, though.

 
After spending 20 years fixing baffle cracks on my Grumman (no oil cooler), I decided that I was going to overbuild the -8's baffles. I went with the baffle-mounted oil cooler because it is simple. I reinforced the heck out of the corner and added the diagonal brace (to the crankcase) and have had zero problems in almost 1200 hours. Good cooling as well - and that is in south Texas!

Paul
 
Yep, keeping the baffle mounted cooler since I have zero issues with oil temp....even with Van's cheap cooler...
 
Brantel said:
Yep, keeping the baffle mounted cooler since I have zero issues with oil temp....even with Van's cheap cooler...
Click to expand...

I've had no problems with my baffle mounted Van's cooler either. About 150 hrs on my 6A. Out here in the west, we get cold winters & hot summers. It's in the upper 90's today.

And while on the subject...........I installed the Van's "shutter" for the oil cooler last year. It worked very well during the winter, as I could get temps up past 200F with just a pull of the knob. It's worked well this spring and early summer too, in the semi open, to full open position. I haven't tried it within the last week with high daytime temps, because the plane is in for it's condition inspection. Since I'll fly from near freezing conditions to the 60/70's in just one day, I think it's a very valuable addition.

L.Adamson -- RV6A
 
I have not seen that before...

alpinelakespilot2000 said:
Based on a bunch of old threads, and in addition to beefing up the outside corner with an additional piece of angle, this is what I did on the inside. Haven't flown yet, though.

Click to expand...

I would be a bit concerned about attaching it to the head. Not sure why but you might consider doing what most of us have done and attach the brace to the case, simply because it is known to work. IMHO
 
RV-6A O-360-A1A Installation

My late 1990s baffle kit said to install a brace from the engine crankcase bolt to the rear section of baffle where the oil cooler is installed. I made a support brace of aluminum angle with the ends cut to a form a mounting tab of the vertical member with the horizontal member cut away. 6 years and 500-600 flight hours later no problem.

Bob Axsom
 
JonJay said:
I would be a bit concerned about attaching it to the head. Not sure why but you might consider doing what most of us have done and attach the brace to the case, simply because it is known to work. IMHO
Click to expand...

I agree - I saw a slow-motion film once of a Lycoming in action, and it was actually shocking how much the head can move relative to the case. I think that the diagonal brace to the case is a more determinate solution. (Of course, the outside of the baffles are attached to the very end of the head...aren't they?)
 
Yes, but with...

Ironflight said:
I agree - I saw a slow-motion film once of a Lycoming in action, and it was actually shocking how much the head can move relative to the case. ..... (Of course, the outside of the baffles are attached to the very end of the head...aren't they?)
Click to expand...

..a two part solution incorporating a split between the two heads.

I saw a local plane with homemade baffles that were one piece between the two heads - they didn't last five hours...:)
 
JonJay said:
I would be a bit concerned about attaching it to the head. Not sure why but you might consider doing what most of us have done and attach the brace to the case, simply because it is known to work. IMHO
Click to expand...

Ironflight said:
I agree - I saw a slow-motion film once of a Lycoming in action, and it was actually shocking how much the head can move relative to the case. I think that the diagonal brace to the case is a more determinate solution. (Of course, the outside of the baffles are attached to the very end of the head...aren't they?)
Click to expand...

Thanks, Paul and Jon, for the input. I'm definitely interested in suggestions, especially since this forum is where I got the idea to go from the oil cooler to the #4 head in the first place. I agree that going from the cooler to the #2 front head would not be good because of the (perhaps significant) relative movement. However, since the aft corner of the baffles are riveted together and screwed to the #4 cylinder head, there should be no relative movement there--in fact, that corner of the baffle MUST float with the aft head, right?

Please see this thread and, in particular, the posts covering the discussions b/w Rick Galati, Mark Burns, and Capt. Avgas...
http://www.vansairforce.com/community/showthread.php?t=44318&highlight=baffle+oil+cooler+brace

To further add to the discussion, it seems to me that if you connect the oil cooler/rear baffle to the engine case via a diagonal brace , you are making it harder for that corner of the baffling to float with the #4 cylinder, not easier. Which is the lesser of the evils?

Please keep the comments coming because I don't claim any expertise here.

 
Last edited:
alpinelakespilot2000 said:
since the aft corner of the baffles are riveted together and screwed to the #4 cylinder head, there should be no relative movement there--in fact, that corner of the baffle MUST float with the aft head, right?
Click to expand...

Steve,
I think I'm coming round to this view too. Perhaps better to tie both sides of the oil cooler to the same thing (the no. 4 cylinder head) rather than two different points that move relative to each other.
 
Makes sense

shuttle said:
Steve,
I think I'm coming round to this view too. Perhaps better to tie both sides of the oil cooler to the same thing (the no. 4 cylinder head) rather than two different points that move relative to each other.
Click to expand...

I can only speak from my experience and others I have seen/heard of. Most have it braced off of the case and it has worked long term. I also claim no technical expertise or reason behind it.
Uh oh, maybe we can start another endless debate thread on where to brace? Ha!
At least we all know what no brace is most likely to do, so any brace has to be better.
 
About all I can say is sort of like Jon did - I have about 1200 hours with the brace going to the case, and no cracks or movement whatsoever. i don't know if others with a brace to the cylinder head have as many hours or not. Yes, I have a sample size of (1), which isn't a lot of data.

I did look at bracing to the cylinder, but something about the geometry of bracing to the case looked more robust to my eye. Basically, I am picking up the load in the middle of the aft baffle (halfway from the centerline of the engine to the head of the cylinder, which should be the place with the most flex (if unbraced). I have no engineering data to back this up, only my experience so far. I go the idea of the brace from several builder's sites before the days of VAF....

Paul
 
Notes From the Field

Approaching 300 operational hours, I can happily report no cracking or trouble spots on the older style baffling have been observed. In my case, the assembly appears as robust as ever. The photos illustrate how I dealt with the perennial problem of baffle cracking that seems to occur with some frequency around the rear baffle mounted oil cooler. YMMV.

2yodd12.jpg
 
Stiffner added.

Hi folks.

I've just completed annual and found no cracks or problems with the oil cooler, but after reading this tread, I added a support-rod.

Before I added it, there was clearly movement-possibities in the baffles around the upper right hand (left side on this pic) corner of the cooler, but now it's nothing.

There's two weak areas on the rod: the two attach points. I'll check them regurarly and see what happens.

I choose to attach the rod to the center of the engine after reading in this tread about how the cylinders move around.

It might not be so visible on the pic, but I've installed the "box" from Vans, which kind of "fills out" the area above the cooler.
(That's where you can see the temp-stickers which I put on in differnet areas underneath the cowling, just to get an idea what's going on)

The ouboard opening of the blast-tube for cooling air will probably not get so much air into it as before, but this is for the engine driven fuel-pump.
That pump actually has another blast tube which opening is not visible on the pic, (outside the left edge of the pic) so I hope those two still will be enough.
(the two other blast tubes are one for each P-mag)


 
Ironflight said:
I agree - I saw a slow-motion film once of a Lycoming in action, and it was actually shocking how much the head can move relative to the case. I think that the diagonal brace to the case is a more determinate solution. (Of course, the outside of the baffles are attached to the very end of the head...aren't they?)
Click to expand...

Paul,

That is exactly why I did not brace my oil cooler to the case. I thought it a bad idea to have part of the baffle attached to a cylinder that has significant movement attached to a fixed position on the case. This will cause something to flex.

My solution was to add a stiffener between the oil cooler and the baffle just above the #4 cylinder so the entire baffle/oil cooler moves in unison with the cylinder.

250 hours without a single crack and the only modification was to add the cross brace.

Click on the following pictures to enlarge them.


(BTW, the engine did not fly with that locknut. It was replaced with an all metal one prior to the first flight. It was there for test fitting only.)
 
Hey Bill, whatever works! I think that stiffening the middle of that long back edge is important to keep the corner from cracking, especially with the mass of the oil cooler hanging out there. My goal was to tie the oil cooler bracing to the central part of the engine, to keep it from moving around relative to the center of mass of the motor. Empirically designed - yes. No cracks after 1150 hours - so some part of the system is working!

Alf - I will be interested to see if your aluminum brace holds up. I used a piece of 4130 steel tube with the ends flattened for the brace - it might be overbuilt.

Paul
 
I am just now working on this area. I have beefed up as many areas on the back and side that I can. I am going to run the long brace from the center of the case but I'm making it out of Carbon Fiber. Not sure if I will run a brace from #4 but I made provisions for it. I'll let you know how it holds up...If I ever get it flying :rolleyes:!
 
Baffle Mounted Oil Cooler

Hmmm.....I installed new baffles when I changed engines about 300 hours ago and moved the oil cooler from the firewall to the left rear corner per the plans and I have much cooler oil than before and no cracks.
I've seen so much talk about bad cracks here that I've been inspecting it on every oil change and everything is still secure so it works for me!
 
mrreddick said:
Hmmm.....I installed new baffles when I changed engines about 300 hours ago and moved the oil cooler from the firewall to the left rear corner per the plans and I have much cooler oil than before and no cracks.
I've seen so much talk about bad cracks here that I've been inspecting it on every oil change and everything is still secure so it works for me!
Click to expand...

Ouch! Just changed the oil yesterday after 376 hours since the new baffle installation and found 3 cracks! Time for some rework and bracing. :(
 
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