O.S. Engines FR5-300 Sirius partial teardown
 

This may be a redundant thread on this engine, but I thought I'd walk-thru my efforts to free up the subject radial engine. It had been stored improperly and was fully gummed up to the point where no movement was possible. There are pics here of the reassembly, which may be helpful to others that find themselves where I was.
The engine originated from an ebay purchase I made on a whim. It was listed as buy it now for $1500 ... no one bought it, I lowballed when I found out he was not an RC guy, and got it for a song.

On receipt, I found every moving part on the engine locked up. The carb and crank would not move. Hot air gun, oil and patience freed both of them, but it was obvious I was only getting compression on one cylinder.
I've done a lot of engine cleaning work, and have had really good results with the crock pot/antifreeze trick, but there are several rubber boots in this one and I was sweating the bearings might be rusted. For these reasons, I tried mild solvents - WD-40, penetrating oils, pure methanol soaks for days. It helped make it spin freely, but when I pulled the valve covers, I found that only three of the ten valves would move. This thing was really stuck. This led me to decide to pull the front end of the engine off to inspect the cam, bearings, and the source of the stickiness.

Removing the drive washer was fairly easy, levering with wood and heating with hot air - careful here with the Woodruff key. When I pulled the cylinder tops, all but one had the valve rocker assemblies fully locked ... with no pushrods involved, seven of the rockers were locked and the rest were stiff. Of interest, the pistons were pristine on top, and the cylinders looked new. It looks like the Original Guy ran it a couple of times, and then put it in a box as is. The manual gives some specific after run instructions, where long term storage requires flushing with kerosene and adding a lot of after run oil.

I pulled the front of the engine off and was initially terrified of what I saw. The bearings had what looked like rust throughout, and even worse, there are a set of small CAM FOLLOWERS (47064000) which drive the PUSH RODS (47066000). These cam followers are driven by the INTAKE AND EXHAUST CAMS ( 47062000, 47062100), and move in an out of the engine FRONT PLATE (47001600) through holes drilled in this aluminum part. Seven of ten of these cam followers were stuck in the front plate and even with heat would not budge. BTW, when I say "heat", I'm talking hot air gun heat ... I do not ever use a torch in these situations. As I pulled parts out, I kept track of the order of removal, and started cleaning. It turned out that the "rust" was actually softened castor oil sludge from all the solvents I had tried. It all came off with a shortened acid brush, and no evidence of rust on the races. Once cleaned several times and oiled, the bearings felt great. Similar situation with the timing gear bearings and the front bearing in the front housing. All that remained was to get the rockers on the cylinder heads freed and the cam followers out of the front plate.

In the case of the rockers, once the grub screw that secures the rocker shaft is removed, on all five cylinders I had to press them out into a wood block with heat applied. Each shaft had black discoloration, that came off easily with a scotchbrite pad. The rocker pivot holes were cleaned out with strips of cloth, or wood strips. Once cleaned, the shafts fit back into the heads and rocker pivots easily. Similarly, the cam followers needed to be heated and I had to use a small rod ground down to the diameter of the pushrods, to the outside of the follower through the cover hole, and then tap on each one until the follower fell out on the inside of the front housing. Again, black stuff on these pins, which came off with a scotchbrite pad. I chucked all these pins in a drill lightly and spun them against the s-brite pads. Once this was done, and the holes cleaned out with wood strips, the followers moved freely.

The whole internals I could get to were cleaned out repeatedly with alcohol and oils until very little gunk was left. Onto reassembly, which is the fun part of this thread.

http://www.rcuniverse.com/forum/atta...mentid=2166371
These are the parts of the front end valve timing. Some have not been cleaned at this stage and I'll show some of that for detail. The vertical set of parts go on the drive shaft with the top most part being "most inside".

http://www.rcuniverse.com/forum/atta...mentid=2166372
Interior of the engine ... note the counter balance ... it helps later with timing.

http://www.rcuniverse.com/forum/atta...mentid=2166373
Front plate on the right. Note the two holes at the one o'clock position ... these used to have cam followers stuck in them solid. The left disc is the FRONT PLATE (47001610). Timing reduction gear bearing at the five oclock position.

http://www.rcuniverse.com/forum/atta...mentid=2166375
Front plate from the front with a wood coffee stirrer to clean out the holes for the followers. Two followers, upper as it came out of the engine, lower cleaned. The ground rod at the top had to be used to get the followers out.

http://www.rcuniverse.com/forum/atta...mentid=2166376
Technique I used required a number of swabs with the stick, wipe out the gunk, repeat.

http://www.rcuniverse.com/forum/atta...mentid=2166377
Top of pic shows the PIN FOR CRANKCASE AND FRONT PL:ATE ALIGNMENT (47001100), which does with the title says it does. It had to be cleaned too.

http://www.rcuniverse.com/forum/atta...mentid=2166378
Front plate installed. The brown you see is the color of the lube I am using - parts are clean. Note the three and nine oclock holes - you can see the edges of the counter balance through them. It is in the WRONG place for timing. You want them so that a line through the timing reduction gear bearing through the drive shaft is at right angles to the edges of the counter balance. The drive shaft needs to rotate about 45 degrees clockwise to be right.

http://www.rcuniverse.com/forum/atta...mentid=2166379
Here is the addition of the REDUCTION GEAR (47062700). Note the easy to see timing mark on the lower gear, and the really hard to find mark on the drive shaft. This is a photo through a magnifier.

http://www.rcuniverse.com/forum/atta...mentid=2166380
Cam thrust washer (A) added

http://www.rcuniverse.com/forum/atta...mentid=2166382
Roller bearing, cam assembly installed. Note timing marks on reduction gear and cam.

http://www.rcuniverse.com/forum/atta...mentid=2166385
Cam thrust washer (B) and crankshaft spacer installed.

http://www.rcuniverse.com/forum/atta...mentid=2166386
Front plate installed, and two cam followers installed.

http://www.rcuniverse.com/forum/atta...mentid=2166387
Disassembled rockers from cylinder head. I found I had to take these apart in order to get the head on easily.

http://www.rcuniverse.com/forum/atta...mentid=2166389
The head gaskets have to be aligned in the head groove to get the head on properly - I put some oil in the groove and the gasket "stuck" in it long enough for me to get the head installed.

http://www.rcuniverse.com/forum/atta...mentid=2166388
First I install the cylinder head with the pushods and pushrod covers in place and tighten the cylinder head screws. Then put on a rocker and get the pushrod end in the rocker socket, then push the shaft through part way. Then add the other rocker and push the shaft the rest of the way - make sure the flat on the shaft is aligned so the grub screw catches it. Secure with the grub screw.

http://www.rcuniverse.com/forum/atta...mentid=2166390
One of five done. One valve is operated in this photo.

http://www.rcuniverse.com/forum/atta...mentid=2166391
Last cylinder about to be done. I finished with no problems except one screw head was partially stripped. I replaced it with a new one I had from OS.

I installed the drive washer and Woodruff key, which went on easier than it came off. I have not put on the rocker covers yet because I want to show my pals that the valves work now!

The destination for this engine is an old Thrush crop duster I got from an estate that needs to be recovered and some wing improvements made. It will be a while before I get to it. I want to run it to be sure I got the timing right, but I also do not want to fill it up with gunk again and hope that a kerosene flush cleans it ... I think if I do run it, I'll flush and then fill the timing area through the nipple with air tool oil and spin the thing with a starter, plugs out.

Nice engine!

Thanks for that Fan Man . Im a sucker for engines and now Im a sucker for that one . Its cool to see the innards and those twin row radials that are made are fantastic as well . I would need to take plenty of pics when pulling down one of those . Let us know how she runs when you get around to it . Cheers the pope

Hi Lightning Fan ,

First off , Thank You for the photos and I'll be following along with this thread to see the test stand runs (Ya KNOW ya want to !!!! :)) .

And yes sir , your idea of filling the crankcase (and some in the cylinders too) with oil and spinning it with the plugs out , getting every bit of the inside sloshed around with it , is the method I use to store all my model engines that aren't in frequent use . I have engines that have sat 20 or 30 years and still spin perfectly because of this . The oil I use is nothing fancy , just good old fashioned automatic transmission fluid .

Thanks guys. I showed off the engine at our club meeting last night, so I can go ahead and complete putting the rocker covers on before I can run it. Yeah, I'm going to run it. We'll see!

Are you still out there?

Yes, I am ... how can I help?

Wow. Great, thanks for responding. I have a stuck cam/follower condition in a Sirius 300 radial I ended up with. Everything else freed up and is smooth. Wanting to access the cam by removing the bell cover. All fasteners are removed and the bell is loose but won't come free
I don't know if the bell is a press fit on the crank bearing race. Dint want to pry if the cover can't be removed from the front.
any thoughts?

It has been a long time since I did this work, but I'm fairly certain that I was able to pull the front plate by soaking it (I remember soaking the whole engine) in solvent, and then I THINK I held the front plate, and tapped on the crankshaft with a prop nut on it, using a block of wood. The bearings were a press fit so they stayed with the plate. I would NOT pry on the plate if I were you. You want axial force on the crank relative to the bearings so the bearings slip off the shaft and not get cocked.

I never ran the engine. I had it nicely stored for some time, and then all my stuff was lost in a shop fire. That engine, along with a lot of other stuff, was lost in heat, water, dirt and ash. Still disturbed by it - I bought the collector ring for it and was really looking forward to putting it in some lumbering bipe.

Wow. Thanks. Never lost anything to fire. That must have been devestating. Sorry to hear.
I am pretty much in the same page with the Sirius.
Wont a puller on the alum. Cover flange mating surfaces naturally, and didn't want to try not seeing the assembly inside( can't find an exploded view of this engine).
It is in the soak again right now. May try to pop it off later.
Not to profit from tragedy but would you like to sell the ring.? I was going to fun this motor with headers only.
It would sound better with a ring lol

Hyjinx is this the correct manual you are looking for? Exploded view & parts ID on page 15 of downloadable PDF
sorry just realized an old post, hopefully your rebuild went smooth?
Attachment 2270488

LightningFan, sorry to hear about your shop loss. That must have been devastating. I landed on your post because it is one of the few pictorial teardowns of the radial I have come across. Thanks for posting them. Did you come across any similar links of overhauls or repairs to this or similar glow radials?

I'm specifically wondering about engine lubrication. If I understand it correctly, intake charge enters from the carb in rear, impinges on master rod & connecting rod assembly. And then out the rear induction tubes to respective head. But I think some portion of fuel mist caries forward through the crankcase, through those aperture holes in the nose plate & lubricates the cam gears, cam plates & valve lifter assembly contained within the nose case chamber. The OS drawing doesn't quite have the parts exploded in their respective order but I tried to illustrate with sketch. Blue lines represents the (oil premix) fuel. Does this look reasonable to you? If so I have some questions, but will save unless I'm barking up the wrong tree.

https://cimg8.ibsrv.net/gimg/www.rcu...da3ea914b5.jpg
https://cimg9.ibsrv.net/gimg/www.rcu...10050ea8c5.jpg
https://cimg0.ibsrv.net/gimg/www.rcu...58a13444ad.jpg

Hi everyone. I wanted to thank Lightning Fan as well as others who have posted on this thread. I recently was able to acquire an OS FR5-300 radial from a lady whose modeler husband had passed. I have torn down/rebuilt/refurbished many 2 and 4 stroke engines but never a radial so I was quite happy to find this thread. I found the photos and information very valuable. So after reading thru this thread I have reassembled the engine. I used this thread to disassemble and reassemble the engine. To clean the engine I soaked all of the various parts in automobile parts cleaner for a day or more. Once clean I began the reassembly.

However, I am trying to find info on valve adjustment (not the clearances but the sequence in which the cylinders fire (i.e. firing order)) so I can properly adjust the valves. I looked on YouTube and could not find anything . Can any of you help? Also, what size 2 or 3 blade props are any of you running on this engine?

Thanks for your help,
Ed
https://cimg5.ibsrv.net/gimg/www.rcu...0e4899be3c.jpg
Engine as purchased
https://cimg4.ibsrv.net/gimg/www.rcu...8c8c970781.jpg
Front cover removed
https://cimg0.ibsrv.net/gimg/www.rcu...d155349fde.jpg
inside the front cover. Cam followers were all stuck.
https://cimg7.ibsrv.net/gimg/www.rcu...932cec333a.jpg
Another view of cams and timing gears
https://cimg3.ibsrv.net/gimg/www.rcu...3636a4f7ad.jpg
Main assembly after soaking in parts cleaner for a day
https://cimg4.ibsrv.net/gimg/www.rcu...4545b210e8.jpg
Back side of engine with view of master rod
https://cimg5.ibsrv.net/gimg/www.rcu...6de555853f.jpg
front cover on and cylinder number one installed
https://cimg7.ibsrv.net/gimg/www.rcu...df7d62360c.jpg
Engine assembled without valve covers
https://cimg1.ibsrv.net/gimg/www.rcu...74b835a5b6.jpg

I don't have that particular engine but the valve adjustment procedure is discussed on page 13 & 14 of the PDF manual I attached in my post #17 along with helpful diagrams. I believe it is common to all 4-strokes: you rotate the crank through power stroke until the dwell period where both valves are fully closed. The pushrods should be stationary of course, they are not being acted on by the cam/lifters. They manual indicates there is also a marking on the driver washer to assist with crankshaft positioning. At that point you make the gap adjustment if it falls outside the prescribed limits with the feeler gauge. The firing order of 5 cylinder radials is 1-3-5-2-4

ptxman thank you very much . Very much appreciated .

Ed