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Oil Cooler – Day 5. Progress.

Today sucked a lot less than yesterday.  I got the oil cooler attached to the engine mount, which is a significant milestone.  I also learned that you can attach anything at any angle using this One Weird Trick, which I’ll describe later.

The oil cooler itself doesn’t weigh all that much, and there are no significant loads placed on it.  The attachment method is Adel clamps, which serve to isolate it from some of the engine’s vibration.  Given that, it seems that the beef I put into the brackets is unnecessary and an example of overengineering.  That said, it’s really, really important to me that the oil cooler stays firmly attached and that it retains its structural integrity until the end of time.

Forward Bracket - Oil Cooler

Forward Bracket – Oil Cooler

The  Weird Trick I mentioned earlier is shown below.  On the right of frame, there is a large-ish piece of angle connected to another angle bolted to the cooler.  The way this works is that there’s enough span on the opposite side to cover the distance needed  by two Adel clamps when the angle is laid up alongside the tube and the adjacent side lines up with the angle connected to the cooler.  This made for a much easier test-fitting, and the same technique is in use on the bracket shown above.

So it’s come to this.  The oil cooler is suspended where it needs to be to get air to it from the big hole in the baffle. At this point, the whole setup will take nearly my full weight, so I’m not terribly concerned about the parts failing.  At this point, the weakest parts are the flanges of the oil cooler itself, and they can be reinforced with angle or bent sheet.

This is the best fit possible for access, airflow, clearance from other important things (fuel line, for example).  There should also be enough room to get a  fiberglass intake plenum between the cooler and the middle engine mount tube.  I measured.  But “best fit” means the least hideous compromise.   Now for shaping the  plenum.  Yay, fiberglass.

Happy New Year.

Oil Cooler, Day 4

This suuuuucks.   I usually feel a certain smugness when my predictions come true, but not this time.  I knew this was going to blow going in, that’s why I delayed it for so long.  I was on the money with this one.  Not one part of this has gone smoothly.  Most of it has to do with the fact that it’s impossible to suspend an oil cooler in mid-air in the place it will eventually go so measurements for bracketry can be taken.

I guess if it was easy, everyone would do it.  Today I took a different tack, and unfortunately I didn’t take any pictures, because there was nothing to shoot.  Just a lot of head scratching and pondering, followed by some fairly intense metal work.  Oh, and I managed to burn the f**k out of my left thumb and forefinger trying to grab a piece of hot angle off the bandsaw table.

At least I have a proper metal shop to do stuff in, even if it is at the opposite corner of the hangar from where my plane is.

Eventually, I was able to draw up some rudimentary plans plans based on some measurements.  That actually worked and I have a main bracket that should, in theory suspend the oil cooler in the correct position from the engine mount tubes in three places. There is also no chance in hell it’s going to break. It’s reinforced at the cooler mount point with .062 angle.

I also need a new oil hose, which is shaping up to be around $250.  Argh.

Oil Cooler, Day 3.

I thought this was going to be a fairly easy exercise.  After all, what’s the big deal, right?  Attach a flange to the baffle, mount the cooler, fab up some fiberglass ducting, slap on a length of SCEET, and presto, done.

Nah.  Slow your roll, dude.

First thing that needed to happen was removing the old cooler mounting flange.   Rather than take the baffles apart, which may have been a poor decision, I figured I’d just unzip all the rivets along the top and left of frame so the baffle can open up, swinging open from the bend right about where the spark plug wires go in.  That hypothesis was borne out.  After some less-than-stellar de-riveting, I have the baffle exposed, but even opening up, it was difficult to get any kind of squeezer or rivet set into the area by the engine mount tubes.  Before anyone freaks out, yes I did clean up the mangled rivet holes, and a couple of them went away entirely when I cut out some excess for the 4″ flange opening, seen in the next shot.

So now there’s a big plate of aluminum doubling up the baffle, to which is attached a beefy 4″ aluminum duct flange from an industrial dust collection system.  Fun fact about that:  Originally, this duct was two pieces, which included a sliding gate to control the amount of air going through the duct.  Cool setup, but it was not to be.  I either had edge-distance issues or conflicts with other parts of the structure, and it didn’t look like I would be able to set up the control cable and mount it.  Bummer, but that’s the way it goes.   I want to return to flight ASAP, I don’t want to be back to project status for any longer than necessary to make this a safe, effective modification.

The final configuration looks a little different from the above.  The flange is flipped over to provide material to rivet along the top where the baffle parts connect, and I cut one of the tabs off to allow for clearance of something else.   But it looks like I have enough room for a 90 bend of SCEET (or one of those boy-racer intercooler inlet elbows) and a diffuser.

This is where I plan to put the oil cooler.  I’ve checked for clearance to mount tubes, wires, and my fuel line (important, that), and it also clears the lower cowl.  I think I can connect to the engine mount with Adel clamps in at least 4 places, both from above and below.  It also looks like there are no immediate obstacles to exit air, but I’m not sure how airflow will be affected by the proximity of the engine mount tubes, but there is nothing directly up against the fins on the bottom.

So I guess my New Year’s resolution for 2018 is to solve all my cooling issues.  Among the things that keep me awake at night is the possibility that the 4″ duct will now steal too much cooling air from the cylinder heads.  Also on the list is to rework the baffle seals to be fewer, more continuous pieces, made of silicone instead of the black rubber baffle material.

Today is New Year’s Eve.  It’s unlikely I’ll be making more headway on this until after I go back to work, but if I keep it chill on tonight’s festivities, I might be able to put in some work tomorrow.

Happy New Year, everyone!

More oil cooler fun

Finding a spot for the new oil cooler was just part of the adventure.  I needed to make room by disconnecting the plug wires and temperature probes from the left side so I could work.  I also needed to find a new spot for the fuel pressure sensor.  Fortunately, that’s easy. I can clamp it to the top strut of the engine mount, pretty much where you see it resting now, top middle of the frame.

Ordinarily, I hate working with steel.  it’s sharp, unyielding, and awkward to work with.   This all changes when you have the proper tools. EAA 96 has a plump machine shop, with a shear, two sheet metal bending brakes, numerous drill presses, grinding wheels, table saws, a massive lathe, and two Bridgeport mills, one of which is working, but neither of which I know how to use.  There are also a number of projects in the hangar that utilize the tube-and-fabric method, so there’s a scrap can full of 4130 steel tubing and sheet cut-offs.  So that’s where I went to get the brackets I needed.   I’m sure there’s some fancy engineer-y math I could have used to bend a bracket so it works in one piece like papercraft, but I was able to get this together with two pieces.  This connects to an angle brace on the cooler and suspends it from the engine mount at the angle and distance I’ll need to get a fiberglass plenum on it, which will connect to the baffle via 4″ SCEET tube.

I chose steel because it was available, I have the tools to work it, and I can get away with less material.  I don’t have the right circumstances to do a solid aluminum webbing, so steel it is.

There will also be a support member on the bottom of the cooler, where I have to battle the mechanics of attaching to the engine mount without blocking the airflow from the cooler.  I paid for 10 rows of cooling, I want all 10 rows cooling.

New oil hoses will also be a necessity.  The top one barely made it to the cooler with an acceptable bend in the line.  There’s no way it makes it now.   I may be able to repurpose the from-cooler line as the to-cooler line, but that’s doubtful, given the fittings necessary.

Oil Cooling hell.

Yesterday, I went from having a flying airplane back to having a project.  For quite a while now, my oil temperatures on hot days and climbouts have been marginal to unacceptable, and since I have the break in the work schedule, I figured I’d do something about it.   So I joined the Compton EAA chapter and rented a space in the hangar for a month while I sort it out.  My oil cooler is the stock Van’s 7-row Niagara oil cooler that seems to work on most RV installs, but not mine.   There are a few reasons this might be: timing, blow-by (which would suck, the cyls are more or less new) bad baffling (worked when I first flew, so wtf) or carbon deposits in the cooler.  It’s actually fine as long as the OAT is 65f or below.  I can settle in to cruise at 190-195F no problem.  But on hot days, or long climbs, I will go above 220 real fast, and that’s no good.   Last year, I purchased a 10-row cooler with the intention of replacing the stock one, but I never put it on.  I first attempted to seal up any baffle leaks.  This improved things a bit, but not enough to matter.  Cylinder head temps are fine.   I’ll hit 400 on those if I mash it and rabbit up to 10,000ft, but they cool down pretty fast once leveled off, and usually settle in around 350-375.  I’m sure there’s more I can do, but for now I need to solve the big one.

The 10-row cooler will not fit on the back of the baffle like the stock one does.  It’s too wide.  There are a number of ways to mount the cooler on the firewall, but none of them work because my firewall is already full of stuff, namely the RDAC, fuel pump, and brake line fittings.

I supposed I could probably move the RDAC and fuel pump, but that’s less appealing to me than mounting on the engine mount and connecting it with a SCEET tube to a flange on the baffle where the original cooler was mounted.

So it’s off to Compton I go, first to do exploratory surgery, then some design work, and then hopefully some fabrication.  They have ALL the tools.

Red Goo.

5 hours.

A shortish day, after Thanksgiving weekend.  But decent.   I got the pax side restraint system involved in addition to the pilot side crotch strap or “anti-submarine” restraint, as it’s called.  That took longer than I thought because of the number of times I had to hop in and out of the plane to find washers and other hardware and tools.

But now they’re both in.  This unflattering photo is just to show that both seat belts are hooked up.


So I went on to the red goo.   I’ve been putting this off, because of my usual aversion to non-solids, but it was finally time to RTV the baffles.   Squeezing a tube of red RTV into all the places it has to go is really hard on the hand muscles, especially when you have to get the nozzle into nooks and crannies now blocked by FWF equipment.

IMG_1685So I’m not the best RTV’er in the world, but I think the bases are more or less covered – a bead running along the baffle meterial, and anywhere light gets between the baffle and the engine.   OK, maybe not everywhere, but everywhere I could get the stuff in there.

IMG_1686Oops.  Didn’t get around the right magneto blast tube.  I’ll have to get that later.

But I was sure to get RTV into all the gaps between baffle and oil cooler, because that’s kind of important, and as for other leaks, we’ll have to see what happens to CHT’s in flight.

More firewall forward progress… And regress.

5 hours.

The latest load from ACS allowed me to finish a couple of things. I got the oil pressure line/oil line adel clamp securing done, I finished the purge valve bracket assembly, I got the fittings installed on the oil cooler, and I actually got the prop governor installed, and the front center baffle reinstalled. I painted the throttle and mixture brackets and put them back on, and I re-secured the current sensor to the alternator wire. This is where it all went south.

I also finished attaching the fuel hose to the throttle body, and securing it to the intake pipes, but this is where it all went horribly wrong. I had purchased a steel 1/4″NPT-AN6 elbow, but I was using one of the blue aluminum ones to get my fit and mount done. The Floscan is on the firewall, and the elbow points toward the intake pipes on the left hand side of the engine. I had the fuel line connected to this. Somehow, in backing out the AN6-1/4″ NPT elbow on the output side of the Floscan fuel flow sensor, I managed to cross-thread the fitting as I was taking it off. Taking it OFF, not putting it on. So what it did was essentially pull on one side of the threads but not the other, kind of just bending the whole thing. Long story short, I completely destroyed the threads on the Floscan and it will have to be replaced. That was a very expensive ($210 from MGL Avionics) lesson in not connecting loads to dry-fitted NPT fittings loose enough to jam up. I did finally manage to extract the threads left in the Floscan housing and re-tap them, but I don’t trust the connection anymore, especially not with high-pressure fuel running through it. Now would be the time to switch to the Red Cube, except that now I’m reading about failures of these units, plus my firewall mount is drilled specifically for a Floscan. The time for experimentation is pretty much over.

I also got a tube of red RTV for sealing the baffles and putting some blobs wherever things might rub that I didn’t get with Adel clamps.

I still have to track down a hose from PHT (throttle body to fuel spider), but that’ll have to wait until tomorrow. My intercylinder baffles are on their way, and once those get installed I can permanently reattach all the baffles. I can also rivet the firewall to belly skin, because I’m giving up on making an exhaust fairing for now.

Baffles 15 – Almost done!

6.5 hours

Today was fairly significant, even though it might not look it. I finished attaching the airseal material to all the baffles, drilled the holes for the spark plug wires, and more or less permanently attached the baffles to the engine.

Since I did the aft left baffle last time, I figured I’d do the aft right baffle, that way I could at least get both of them on and done. this one actually proved to be pretty easy, with no surprises. After all, it was more or less about doing the spark plug wire grommet holes, deburring everything, and attaching the airseal with rivets.

The connection in the middle where the baffle connects to the bracket got changed a little. Originally, I had the bracket pinning the airseal between it and the baffle, but that looked stupid and distorted the baffle, so I cut some slits in the baffle to get around the bracket. It should seal fine, and eventually the rubber will mold itself around the bracket with hours of heat and use.

With both sets of aft baffles on, I installed the oil cooler. This was one of the items that’s been bugging me for a while, and now it’s finally done. I’m still not happy about the amount of flex in the aft baffle where the inboard oil cooler attaches, but I’m not exactly sure what to do about it right now. Any reinforcing strut that picks up a convenient attach point on the engine would interfere with the fuel injector lines, which is no good. This shot shows the beefy angle bracket I installed last time to reinforce the connection between the side and rear parts of the baffle, and gives the oil cooler bolts a more solid structure to hang from. Lots of people report problems in this area, but this, and a strut for the other side usually fixes it.

So here it is, the bane of my life, nearly finished. I recut the governor baffle, because the governor hole didn’t seal well enough for my taste, and this time around, I left a big dog-ear flap on the front to aid in sealing with the cowl, should the need arise. I didn’t take a lot of photos of the process of installing the governor baffle seal, because it’s difficult to shoot pictures while you’re using both hands to wrestle with airseal. The end of the governor is bigger than the housing where the seal sits, so you have to cut the hole big enough to get over the end, but small enough to seal on the governor housing.

This process also revealed a small flaw in my governor baffle design: I can’t actually take the baffle off without removing the governor. I can live with this, I think. But what I have to do to get at the governor nuts is take the left front baffle off, which can’t be done with the governor and its baffle in place. But there’s always a way. It’s messy, and it’s a hack, but disconnecting the oil line from the #2 cylinder allows me to drop the left front baffle out of the way and slip it out past the governor baffle.

I also put the airbox on, just to see everything in place, and make sure it all still fits. What you see in the photo is essentially the final configuration of the baffles and intake.

I still have a few minor things to do. I need to drill the duct holes for the mags and alternator, but I don’t want to do that until I’ve figured out control cable routing. I also need to make the rods securing the baffles at the bottom where they wrap around the cylinders. Once that’s all set up, I’ll need to squidge some red RTV in where the airseal meets the baffles, and around the engine-baffle interface in various places, plus around the corners of the oil cooler so I get maximum efficiency from the airflow through that.

Baffles 14 and Oil Cooler

8 hours.

I haven’t been working on this a lot lately, because my motivation is low, and I’m traveling for work. But I can report this time that the project is sucking a little less. Last time, I’d gotten the baffle seal material trimmed. Since then, I’ve been knocking items off my list, one by glorious one. At this point, baffle seal material is riveted to both front outboard baffles, and left rear baffle.

In addition to that, the oil cooler bracket is done, and the left rear baffle parts are all riveted together. This went surprisingly well, except for the fact that I initially installed the oil cooler double upside down, which sucks, because just flipping it over doesn’t work: The damned holes don’t line up on the sides anymore. I managed to fix this without making a huge mess, but there were a few too many extra holes for my comfort, so I beefed up the section in the corner with a piece of angle running down the vertical where the side and rear join up.

This is a shot of the rear baffle section before I cut out the hole for the actual cooler.

Making the hole for the plug wire grommet was also fun. Not that big a deal though. And finally, everything became a more or less unified piece of equipment that will hopefully serve its purpose as part of the cooling system. With the angle going up the vertical on the outboard corner, this thing is really solid, and hopefully stands up to all the engine vibration. I’m not crazy about the fact that the inboard side of the cooler is attached directly to the baffle, so I’m going to look at options for transferring the load to the engine case somehow.

Here’s everything riveted together, except the baffle seal. I’ll try to find a better photo. When I was doing this, I didn’t take a lot of photos, because I’m experimenting with a new workflow that involves periodically stopping to clean up the mess that accretes around the work area, such as tools, clecos, harware, and cast-off bits of aluminum. At some point, I’ll roll photos into that process. Yeah, I know, seven years on is a little late to be experimenting with new methodologies, but that’s why it’s called “experimental” aviation.

Linkages, obstacles.

I read all the warnings. “Use a Van’s-approved engine or you’ll have a ton of trouble making everything fit.” Or this one: “By the time you convert the engine to what you want, you’ll have spent just as much money as if you’d bought new.” Tinker or fly? So, I now have a laundry list of issues related to my particular setup that will now require no small amount of customization, some of it in steel, which I haven’t had much to do with since shoehorning large snowmobile engines onto the backs of go-karts back in the mid-80’s. Here’s the list of fun so far:

-Throttle body interferes with the starter. The Kelley Aerospace starter has a retaining bolt on it that prevents the TB from being mounted in the diaphragm-up position.
-Stock brackets won’t work. Either the mixture or the throttle arm goes the wrong way when pushed, so a bellcrank is probably going to be required.
-AFP throttle body won’t play nice with the airbox. More fun with fiberglass.
-Fuel hose from engine pump to TB inlet is too short in any position except the one that won’t work because of the starter.
-Custom-length quadrant cables will be required.
-Throttle and mixture arms interfere with factory-set linkages when oriented in directions that work for me. I’ll need a straight arm from Don at Airflow.
-Right magneto interferes with battery box. Will need to be re-indexed for harness to clear and be retimed.
-Left magneto had to be removed to adjust oil cooler fitting. Timing will need to be reset.
-Breather tube is a little close to the RDAC. Should be OK though.
-Alternator interference unknown at this time, since I haven’t purchased it yet.
-Oil cooler taken off the engine when I got it is cracked. Need a new one.