Archive for the ‘Firewall Forward’ Category

Plenum & Oil Hoses

PA220002.JPGWhile I was in the process of replacing my accessory case, I decided to modify the inside of my plenum to even out my CHT’s. I added a small ramp about halfway between the 2 cylinders on the left side of the engine. Before the mod, the back cylinder was cold so the theory is that the ramp will deflect more air towards and through the aft cylinder instead of letting it pass to the back of the plenum. It worked pretty well, actually.





PA230003.JPG I guess I didn’t take any pictures as I was building these new hoses. I was so disgusted at having to re-do all of them that I just wanted to get it done and not stop for photos.

I ordered brand new Aeroquip AQP fittings and brand new Aeroquip stainless hose. I know you don’t have to use fire shield on stainless lines when used for oil, but stainless really scares me in terms of chafing potential so I went with the fire sleeve. Making hoses out of high quality stuff is REALLY expensive. I hope when I decide to sell my plane the buyer appreciates the difference!

I also pressure-tested 2 out of four of these hoses to 600psi. They really shouldn’t leak or fail again! Two dead stick landings are plenty for me for about the next decade or so!

Oil Pump & Accessory Housing

Things haven’t been going so well for my little airplane these days. I keep getting stranded away from home because my oil pump won’t seem to stay primed. When I start the engine, it fails to make oil pressure. There are all kinds of hocus pocus tricks you can try to get the pump primed again and I’ve tried them all. TWICE!! I finally reinstalled my custom made fitting on the left side of my engine case and used a T-fitting to add a primer line (the orange line in this picture). It worked, but not for long…

The long and the short of the situation is that my oil pump gears and/or the oil pump housing had worn beyond tolerances and could no longer make pressure. This is my accessory housing after I removed it from my engine. The plate in the middle covers the oil pump itself, which consists of 2 hardened steel gears.

Now: I’m no engineer, but even I can see where putting 2 hardened steel gears inside an aluminum housing might lead to some wear issues.

This is the aluminum plate that covers the oil pump and holds the gears in place. You can see where the gears have caused some wear marks on the plate. A lot of people are successful in restoring oil pressure by lapping this plate and reinstalling it. By the time I had gone to the trouble of removing my accessory case, I was going for the sure thing… not a maybe.

Here are the gears in the housing. The square drive on the lower gear engages on either the crank or the cam (can’t remember now) which then spins the gears. The backside of the top gear (not shown) has the square drive output for the tachometer.

You can see the wear on the housing from where the hardened steel gear has rubbed. There was a similar wear pattern on the other side of the housing, too.

I could have the old housing remanufactured for $850 or purchase a new housing for $905. The new housing is on the right. :-) Ouch.

The new accessory housing from the backside. Sure is pretty with that gold finish…

I’ve never actually painted a chess set, but I imagine it to be very similar to taping off and painting this accessory housing.

I reinstalled the accessory housing. Sounds simple enough, right? Wrong. I needed all new gaskets for everything attached to the accessory housing including: Both magnetos, the starter, the generator (capped), the tach drive housing and, yes, even the oil sump. By the time I purchased the accessory housing, a new oil pump kit (gears and the aluminum door) and all the gaskets, I had spent the better part of $1500. All I can say is that I’m glad I could do the work on my own because I’m sure it would have been another $1000 in labor if I was paying somebody else to do it!

Airwolf Adapter & New Oil Cooler

I put the porcupine fins on the oil filter and started building brackets for the remote filter installation. It’s surprising how much time it takes to fabricate brackets. If you look closely in the picture, you’ll notice that I used waxed lacing to hold the Adel clamps closed. The lace lays down fairly flat and allows me to get a nut and bolt started without too many cuss words. After the nut is started, I use a razor blade to cut and then remove the lacing.

The Airwolf oil filter adapter pickup is really a work of art. In my Continental O200 installation, I removed the original screen and replaced it with the Airwolf adapter. The fittings shown in this picture are just for test purposes. I’ll probably end up using 2-90 degree fittings.

Once I was satisfied with the fit of all my new brackets, I primed and painted everything white to match the engine mount. I’m pretty happy with how everything turned out. Note that I’ve removed the porcupine fins. I talked with a friend who tried them and said if they helped at all, it was VERY little. I’ll be sending mine back. For $100 they need to be more effective than the width of my temperature needle!

The pictorial manifestation of my oil cooler situation. I started with a used Stewart Warner cooler. I then switched to a used Positech cooler. I have now decided to go with a brand new Setrab cooler. It’s the one on the far right in this picture. It has about the same frontal area as the other two coolers, but only half the thickness. This is a 10 row cooler so I’m hoping it’s adequate for my O200. A friend is using a Setrab cooler in his Giles 200 with great results. The price was right at only $106–BRAND NEW!

Of course in true homebuilder spirit, I had to make a few modifications to my brand new cooler! I cut the mounting tabs off one side of the cooler to allow it to slip through a hole in my bottom engine cowl.

This was the painful part. I marked the outline of the material to be removed (yes, cut out) from my lower cowling. The idea is that I’ll slip the cooler down into a new air duct fabricated to provide a direct stream of fresh air to the cooler. So much for my shiny checkerboard cowling!

With the hole cut in the cowling, it was time to start fiberglassing in a few mounting pads to support the oil cooler. I used white duct tape to hold the cooler in place and then a couple of blocks of foam to help shape the mounting pads. This will be a multi-day, multi-step layup process so keep following along and the method to my madness will [hopefully] become apparent.

This is how I left the project when I left the airport at about noon today. With any luck, it’ll still look somewhat like this when I return to the airport tomorrow morning. It’s been getting into the 90’s each afternoon so I’m guessing the fiberglass will have cured by tomorrow morning!

We had a very special visitor at the airport today. Dick Vangrunsven of Van’s Aircraft stopped through on his way to Oshkosh. A few of us went out for BBQ this evening and had a great time listening to Mr. Vangrunsven. He’s a very smart and interesting person to talk to and I’m honored to have met him. When all the dust settles 50 years from now, I believe Mr. Vangrunsven will be seen as one of the top 5 most influential people in general aviation in recorded history. On top of that, he’s a really nice guy.

Still more cooling…

These are my upper and lower inner cylinder baffles. They rest on the top side and bottom side of the cylinders and are intended to force the air through the cylinder fins rather than allow it to flow through a big, gaping hole. I’ve been using nothing but safety wire to hold these in place, but have decided that a spring would be nice and would allow for easier removal and installation.

Here’s a birds-eye view of my engine installation with the inner cylinder baffles in place. Keep reading to see where I ended up modifying this setup to open up the top side of the cylinders a little more.

An overhead view of the engine with the newly redesigned plenum. Unfortunately, as near as I can tell, the new plenum design did absolutely nothing for me! Bigtime bummer.

Believe it or not, this little mod was good for 10 to 15 degrees in oil temperature! I bent a 3/4″ x 6″ piece of aluminum to a 45 degree angle and taped it to the aft lip of my cowling. The idea is that this lip causes a low pressure area in the exit airflow and helps to suck the hot air out of the engine compartment. Pretty snazzy.

It’s annual time so I started an oil change. This is the first oil change with a spin-on filter so I cut the filter apart to look for any signs of engine wear–like big pieces of metal stuck in the filter. I’m happy to report that none were found.

Since I’m now filtering my oil with a real live filter, the oil screen is no longer necessary. I used a torch like you’d use for sweating copper pipe to de-solder the screen from the big oil screen nut. This way, I can just change the filter and not worry about pulling the screen off for future oil changes.

While I had everything apart and just to make sure I wasn’t chasing a ghost, I decided to re-check the accuracy of my oil temperature sensor. I heated some water and stuck a cooking thermometer in the water alongside the oil temperature probe. I then compared the reading of the thermometer with what I was seeing on my oil temp gauge in the cockpit. I’m happy (I guess) to report that the two read within 2-3 degrees. (The width of the needle.)

I decided to open up the top side of my cylinders even more. I used a bent piece of wire about the gauge of a coat hangar to slide around the cylinders to provide a mounting point for my inner cylinder baffles. I took the fiberglass baffles that were on top of the cylinders and moved them to the bottom of the cylinders. You might also notice that I trimmed down the cylinder baffles a bit where the intake air first hits the cylinders.
I had a little issue a week ago or so where I had no oil pressure on startup after leaving the plane sit for about 2 hours. After a bunch of troubleshooting, I came to the conclusion that my oil filter and cooler system was plugged up. You’ll remember that I used a port off the left side of the engine to connect oil lines that would feed my spin on filter and oil cooler in series.
What I failed to account for in the original installation was that if either the cooler or the filter became plugged for any reason, the engine would be starved for oil. There were no bypass valves. Duh. Luckily, I discovered this problem on the ground and not in the air or we could have had serious problems.

After realizing the error of my ways, I decided to purchase an Air Wolf spin on oil filter adapter kit. When I called Air Wolf to talk to them, they said they’ve got a new filter fin kit that supposedly reduces oil temps by 20 degrees. What the heck, I thought, and I bought it. This thing really looks like a porcupine. It’s going to be a bit of a challenge to find a place to mount this bad boy.

Here’s another view of the filter fins. You can see that they cover about 300 degrees worth of the cooler. I’ll duct some cooling air to the filter to maximize the effectiveness of these fins.

Just in case the fins aren’t enough, I bought this spin on oil cooler port adapter from Steve’s Aircraft up in Oregon. This little baby spins on between the Air Wolf remote mount pad and the filter. It provides a pressure bypass valve and an in and out port for an oil cooler installation. After talking with the folks at Air Wolf, I discovered that the Air Wolf system doesn’t have a bypass valve per se… They, instead, count on the bypass capabilities of a CH43108 aircraft filter. That’s why it’s important to have a bypass valve for the cooler installation.
With all this stuff going on and a bunch of other things going on in my world, I’ll be lucky to have my plane flying again before the end of July. Bummer, really, because I was hoping to make it to a fly-in at Alamosa, Colorado on July 16th. I don’t think that’s going to happen. Oh well, there’s always next year!

Plenum Progress

Here’s a bird’s-eye view of the new plenum pieces painted and installed. I’m very happy with how they turned out. Now it’s just a matter of connecting the dots–joining the original plenum with the new pieces by fabricating a fiberglass lid.

Once again my good friend Phil came to my aid with my fiberglass work. He’s got more fiberglass experience and tools than any sane person ought to have. Using Phil’s equipment and expertise, we made a vacuum-bagged layup consisting of 2 layers of cloth, a 1/8″ layer of foam and another 2 layers of cloth. To complete the vacuum bagging package, we laid on a layer of peel ply and then a layer of breather cloth. The whole mess then goes into an airtight bag and a vacuum is drawn.

This little pump supplied the vacuum. We placed the whole package on the top of my engine with bags of lead shot to hold everything down nice and tight against the existing plenum and my new metal pieces. It took about 6 hours to cure to the point where I could remove the vacuum. I left the weights and everything else in place until the next morning.

I was back at it again first thing Saturday morning. This is what it looked like as I started pulling the peel ply and breather cloth off the cured part. The gold color is the foam core as the 2 layers of fiberglass are pretty much transparent once all the excess resin is sucked out. The piece is surprisingly light.

I laid the piece back on the engine to get a feel for just how much I’d have to trim. It fit surprisingly well, but will obviously need to be trimmed.

With the front-to-back trimming complete, I next marked strips along each side. I’ll use a Dremel tool with a small cut-off wheel to carefully remove the first two layers of fiberglass from the strips along the edge. This will allow the fiberglass, without the foam core, to rest on my new metal flanges.

Once the first two layers of fiberglass were removed, I just had to scrape the foam core out to leave the remaining 2 layers of glass exposed. This wasn’t a difficult process.

To finish the flange, I used a Dremel tool with a cone-shaped grinding tool to grind a 45 degree bevel in at the edge of the remaining foam core along the length of the flange. Even using the vacuum process, it’s easier to get fiberglass cloth to lay down over something less than a sharp 90 degree angle. After the bevel was cut, I applied another 2 layers of cloth tape along the flange so that the finished flange is 4 layers thick. 4 layers of cloth wouldn’t be enough for the entire plenum (without the foam core), but it’ll work well for the flange.

I drilled and clecoed the new fiberglass piece in place. I laid the blue tape on a flat surface and made my marks for the holes so they’d be equally spaced. It’s tough to determine the spacing on a curved surface so the tape works well. I drilled through the new plenum and into the flanges of my new baffle pieces. I also drilled and clecoed a few holes through the new plenum into my old plenum pieces.

I took the entire plenum off as a single piece. My plan is to remove 2 layers of cloth and the foam core where the new piece will mesh with the old plenum halves. This should make it easier to graft the new piece to the old pieces and create an invisible transition so that the entire plenum will be a single piece. Obviously there are some openings in the corners that I’ll have to address with additional wet layups.

More cooling issues

Looks like I did the victory dance a little early with my cooling issues. When I went out to fly my plane in 74 degree temps, the oil temperature went straight past redline. I landed as quickly as I could to prevent any damage. I’m convinced that the oil cooler isn’t doing much at all. I’m thinking the only reason it worked last year when it was mounted on the top of the case is that cool air blew through the cooler and cooled the case itself.

Before I started on more drastic measures, I decided to bypass my new thermostat to make sure it wasn’t causing my cooling issues. In this picture and the last picture, I’ve capped off the thermostat and joined the hoses with AN couplers. No change. Still ran right to 225 degrees and was headed higher when I landed after 3 laps overhead the airfield.

I dug through all the junk that came with my airplane when I purchased it 7 years ago and found the original baffles. There’s no way I’m putting this junk back on my shiny new airplane, but maybe it’ll be good for a pattern. Or not. In the end I decided I like the plenum over the cylinders and how it fits… I just need to extend it over the top of the case to (hopefully) provide better cooling.

I used my contour tool and some foam core board to make a few patterns. I have previously used poster board in these situations, but find that it gives too much for an accurate pattern. My plan is to seal off the case from just behind the spinner to just in front of the engine mount bolts.

Here’s the aft piece fabricated from .032″ aluminum. It fits the contours of the case well enough that it shouldn’t be a problem sealing it up airtight with some RTV. If the combination of the RTV and the plenum isn’t enough to hold the piece in place, I could always attach a few brackets to mechanically hold it in place.

Here’s the nose piece just setting in place for a preliminary test fitting. There are two attach holes on either side of the crank flange that will allow me to attach this piece to the case. I think the holes were used as part of the stock baffling installation. In any case, a quick trip to the aviation aisle at Ace Hardware and I’m all set with the proper 1/4″ coarse threaded bolts.

With the fore and aft partitions in place, it was time to plug up the irregular-shaped holes on either side of the front of the case. Again, I used foam core board and my contour tool to come up with the shape. After I took this picture, I marked the patterns to be trimmed so they’ll just meet up with the forward partition.

I needed a flange along the top of the forward and aft flanges so I broke out my stock of Van’s-supplied stiffener material. Van’s fabricates this stuff for use as control surface stiffeners. It’s the greatest thing since sliced bread as far as I’m concerned. I ordered a bundle of it and have found many uses for it during the Midget Mustang project. Here I’ve cut notches along one side so it can follow the gentle contour of my new baffle.

Here’s a shot of the baffles after priming and after the flange has been cleco’d in place. I always get excited when things start to come together like this.

With the flanges in place it was time to fit the pieces at the front of the case to the left and right of the crank flange.

I’m pretty happy with the way these fit. After a few tweaks I separated all these parts, primed the remaining pieces and riveted everything together. The next day I painted everything black to match the existing pieces at the valve covers. I don’t have a picture of the freshly painted pieces because they were still tacky when I left the hangar on Saturday afternoon.

While waiting for the paint to dry, I decided to tackle another little squawk that’s been bugging me for almost a year. I just don’t have enough elevator trim authority. At different phases of flight I find myself trimming to the full up and full down positions and wishing I had more. The painted piece to the right side of this picture is my existing trim tab. The one on the left is the replacement.

Here’s a better shot to see the difference in size between the old and the new. Believe it or not, the new tab is more than 50% larger in surface area. I’ll start with this and if it’s too much I can always trim it down a bit. I can’t believe I put this project off for almost a year. Once I got started on it, the project probably only took me 30 minutes to complete.
I was really busy at work during the months of April and May, but I’ve vowed to be less busy during the month of June. I’ve already missed some fantastic flying days so I’m highly motivated to return my Midget Mustang to flying status as soon as possible. I’m off work for 5 days in a row starting next Thursday. I’m hoping for some serious progress during that time.

Gotta show a picture of my new beater truck. I bought this in anticipation of my next project… finishing my basement! 4 x 8 sheets of drywall will certainly fit better in this truck than they’ll fit in my VW Passat! It’s not much to look at and it doesn’t get very good gas mileage, but it’ll serve a purpose. I’m finding it really fun to not have to worry about where I park for fear of door dings, too!

Tail Spring Fairing & Breather Tube Mod

Friends have been bugging me forever to fabricate a fairing for my tailwheel attach bracket. It’s a big, draggy bracket that attaches to where the original leaf spring tailwheel attached. The first step in the process is covering everything with either shelf paper (the white stuff) or vinyl tape to protect it from my sloppy application of cloth and epoxy resin.

With the area protected, I used modeling clay to form the shape of the fairing. The flash from my digital camera really emphasizes the surface irregularities. It really did look a lot smoother than that to the naked eye. Not a huge concern for a part like this, I guess. And the fiberglass cloth itself kind of smooths out smaller surface lumps and bumps.

I covered the clay and the surrounding area with PVA mold release and then applied 3-4 layers of 6 oz. fiberglass cloth and epoxy resin. This is the part after the resin is cured and the part has been separated from the aircraft.

This is the part after I’ve finished removing the clay and pealing the PVA mold release. I’ve also done some preliminary trimming with a Dremel tool equipped with a cut-off wheel. It was still a little cool in my hangar so the part hadn’t really cured enough to start sanding on it. I’ll probably take time to sand, fill and prime it before I put it on the airframe for a test flight. I tend to get some oil back there and I don’t want an unprotected, raw fiberglass part to get oil soaked. It’d be nearly impossible to get the paint to stick if that were to happen.

Another little nagging project I’ve been meaning to complete is the installation of a modified breather fitting. The original O-200 breather tube fitting is simply the threaded fitting you see in this picture. When screwed into the case, the fitting is flush with the inside wall of the case which allows oil to easily run down the inside of the case and get sucked out via the breather tube. If you look closely at the fitting in this picture, you’ll see that it’s been machined slightly to allow a bigger inside diameter on the treaded end of the fitting.

The larger inside diameter allows a 1/2″ copper tube to slide in and be silver soldered into place. Once the tube is soldered, it is cut down to 2-3/4″ from the end of the threads. This extended breather vent still provides the “breather” function, but it makes it more difficult for oil to actually escape the engine. (Or so the theory goes…) Big thanks to Dave Biesemeier–friend and machinist extraordinaire for his efforts in modifying the fitting.

This is the original fitting as it was installed on the engine at overhaul time. It was powdercoated with the rest of the engine at that time.

I lost the red powdercoating, but I still think the gold looks cool against the red. You can also see the bead of Permatex thread sealant that oozed out of the threads as I installed the fitting. On the advice of Dave B., I’ve started using the sealant on pretty much all my pipe threads. Never had a leak on a fitting with the sealant. Forgot to apply to one fitting on my oil filter housing and had a leak. Definitely worth the time and effort to use.

Plenum, Oil Cooler Duct & Upholstery

My poor plenum tops have taken a beating with my oil cooler installation and then relocation. It was a shame to screw up my checkerboard paint, but it’s all in the name of progress, right? After grinding out all the previous ducting I had to re-glass the holes near the inlets. I used clay as a backing and then glassed the holes shut.

The lower half of the new duct to the oil cooler is attached to the cylinder baffles. As you can see, the cylinder baffles are held on with safety wire. I put a couple of nutplates in the lower duct that the top duct will attach to. The gap will eventually be filled with a neoprene ring. I needed a little space because there will likely be movement between the engine and the oil cooler (because the cooler is mounted to the engine mount).

The plenum is in place and completes the new duct to the oil cooler. With all the screws in place, it’s really a solid setup.

Here’s a birds-eye view of the engine compartment as it currently stands. You can see the patches towards the inlets where I removed the previous ducting. I used duct tape to seal the gap in the new plenum for now. Once I know the system is going to work, I’ll fabricate a neoprene sleeve for the gap.
I went up on Wednesday of this last week to test the new installation. I ran the plane wide open for 30 minutes to see how high I could get the temps In the old days, I could easily flog it into going to 225 degrees. I’m happy to say that the best I could do running around at 3000+ rpm for a full 30 minutes was 210 degrees. I have no intention of running around at 3000 rpm in normal operations so I’m calling this a success.
I de-cowled the airplane after the flight and found 2 small oil leaks. The first was an easy one… in fact it was one of those “duh” moments… The hose on the breather port was night tightened down. Woops.
The second leak came from my modified reducer fitting on the right side (looking at it) of my oil filter adapter. I remember being excited to see if the modified adapter was going to solve my clearance issue so I put the fitting on without using the Permatex teflon sealer. It leaked. Woops again. I stopped by the hangar last night at about 9pm on my way home from work and fixed both these issues in hopes of flying to breakfast this morning.

The other thing I did yesterday was that I picked up my new seat cushions with the new upholstery. A guy over in Brighton, CO built the seat cushions and did all the sewing, too. I could have picked from any material in the world for my upholstery, but ended up picking sheepskin. I purchased 2 pelts from Colorado Sheepskin Factory in Denver.
I was originally planning to go with a dark grey color, but nothing I found really blended well with all the other colors in the interior. I ended up going with black because black seems to go with everything. Now that it’s installed, I’m very happy with the look.
I went out to the airport today (Friday) with hopes of flying over to Greeley (KGXY) for breakfast. Unfortunately, by the time I arrived at the airport at about 7:30 this morning, the wind was already blowing in a direct crosswind at 16 knots. It would have been do-able, but I figured I’d get my fanny kicked all the way to and from Greeley so I decided to stay on the ground and work on the next project.
What’s the next project? Stay tuned for pictures and a narrative in the next entry.

Upper plenum and exit air diffuser box

I spent a little time out at the hangar today and continued my work on the ducting for my relocated oil cooler. I’m making the new duct as a 2-piece part. The lower half will be attached to the cylinder baffles and the upper half will be a part of my fiberglass plenum. There was a pretty large volume of space to fill so rather than use 20 pounds of clay, I first filled the void with shop rags and then put duct tape over the rags so the clay wouldn’t stick to the rags.

With the rags and the duct tape in place, I started adding clay. It took me about 40 minutes to achieve this shape. As a little tip, it is tremendously easier to work with this clay if you first heat it thoroughly. I’ve got a microwave I use to heat my lunch in every so often. Turns out it heats the clay up fine, too!

Once I was happy with the overall shape of the clay, I painted it with 2 coats of PVA mold release. Again, it pooled in the low spot, but these dimensions aren’t critical to the thousandth of an inch so I’m not too concerned. It’ll just take a while to dry.

This is the plug for my oil cooler exit air diffuser box. Again, to avoid having to work with a 20 pound glob of clay, I started with a foam core. To help stiffen the foam up, you’ll remember that in a prior work session I coated the foam with a mixture of micro balloons and epoxy. This method seemed to work pretty well.

In the process of poking around the engine compartment looking for air leaks in my cooling system, I think I may have discovered the cause of my erratic CHT readings on my #2 cylinder! I’m not sure if this worked its way to being loose or if I somehow failed to torque it down, but this is how I found my #2 cylinder temperature probe when I de-cowled the engine. I love it when a solution is simple and obvious!

Oil cooler ducting

I spent about 1-1/2 hours out at the hangar this evening after I finished my 4-day trip. This is my new piece after I’ve pulled it out of the clay mold and scraped the clay off. Of course I’ll need to trim it and do a bunch of sanding and filling before it’s anywhere near finished.

Since I’m abandoning my “Y-duct” near the front of my plenum, it was time to hack off my handiwork. Obviously the entire plenum will need to be refinished once I’m finished with the new oil cooler installation.

In this picture I’ve trimmed the new piece and have cut back the original plenum. I’ve also sanded a strip of the plenum all the way down to the original fiberglass. This will give me a nice surface to splice into the old plenum to continue the chamber back to the oil cooler. The plan is to have the bottom piece of the chamber attached to the cylinder baffles and the top top piece will be an integral part of the plenum. I’ll probably end up creating a gap between the cylinders and the oil cooler and bridging the gap with neoprene. I’m afraid the part would crack due to the shaking/twisting of the engine relative to the engine mount. Since the oil cooler is hard-mounted to the engine mount and the cylinders are attached to the engine which is attached to the mount via rubber mounts, I’m guessing I’ll need to make allowance for the movement. I’ll take a picture and point it out when I get to that point. I’m having a tough time describing it.