NC9067K

Stinson Topics

2/21/02

Tach Drive Housing

    From the time I first saw 67K, it has leaked oil.  Over time I've replaced the pushrod tube and rocker cover seals with the red-silicone type and that has helped.  The last leaker I have to deal with is the Tach Drive Housing.   It's easy to remove.  1. Remove the tach cable and 2. remove the two 1/4" bolts that secure the housing to the accessory case.  The problem is, it's hidden between the mags and REALLY hard to get to.  Since I was doing some work on one of the mags, now is the time to go after that leak.

    I bought a seal set from Susan at A-1 Service.  All it had was a mount gasket and a small shaft seal.  Once I had the tach housing off, it was difficult to tell how the seal was installed.  One end had the driven gear and the other had what looked like a steel washer pressed in.  The only way to solve this problem was to take it apart.  I made an aluminum nest to hold the driven gear without damaging it and took it to the press.  Presto!  it popped right off.  The shaft then slipped out of the housing and another mystery unfolded.  What looked like a steel washer before was actually a shaft seal with a metal outer housing.  The new seal is different but it has the same OD and ID.  It's a little thinner than the old seal, that might mean that the ID of the new seal may not contact the shaft in exactly the same spot (which might be a good thing.)  The shaft has a shiny spot where the seal was rubbing on it but doesn't look worn (the picture makes it look much worse than it really is.)  I'm going to clean the shaft up, reassemble it, and see how it does.

2/27/02

I've reassembled the drive unit-no problems.  The new style seal fit snugly in the ID of the housing and the shaft has some perceptible drag when you turn it with your fingers--you can tell that the seal ID is snug.  I'll be putting it back on the engine this Saturday.

3/2/02

Success!  The tach drive is back in, the left mag has been reinstalled and timed, and the engine runs fine.  Now I taking off #4 and #6 cylinder to see why they have low compression.

3/16/02

Removed #4 & #6 Cylinders.  I really expected to see stuck rings in #6 but I was wrong.  They actually looked practically new!  Soon, I'll remove the valves and see how they and the whole cylinder measure out.  There's got to be *some* reason they both have low compression.

3/18/02

I copied the pages of the Franklin manual that covers the work I'll be doing to the cylinders.  If you're interested, you can get the copies in a .pdf file by clicking this link: Franklin Information

4/8/02

The cylinders are off and disassembled.  I found a little carbon buildup on the exhaust valve stems and a lot of crud collected on the backs of the intake valve heads.  It looks like the crud was beginning to encroach on the mating surface of the valves--that was probably what was causing my low compression.  There's no sign of erosion of the valve and they measure within spec.  I'll be cleaning them up and lapping them.   The cylinders both measure up at 4.5015 which is only .0015 oversize from new.  I should be able to hone them and still be well within tolerance.

 

#4 Exhaust Valve area

#4 Exhaust Valve

Notice the carbon deposits on the end and near the head. No deposits could be seen in the area that contacts the guide.

#4 Intake Valve

Notice the crud buildup underneath the head. You can see it encroaching onto the mating area of the valve.

#6 Cylinder Bore

The reflections and lighting don't really show it well but the bore looks fine. It measures only .0015 oversize from new spec.

#6 exhaust valve "freckle"

After I lapped the exhaust valve for #6, I noticed a dark area in the metal right on the mating surface of the valve. All the experts agreed this was typical of a "burned valve". I was surprised, I expected to see erosion. Anyway, the valve needed to be ground to see if it could be eliminated.

Exhaust valve after grinding

Hooray! It only took the lightest of grinding to totally eliminate the burned spots

Exhaust valve after lapping

The same valve after lapping. I thought it was done but now that I've seen this picture, I'd lap it a little bit more.

 

5/11/02

Ut-oh   minor set back.   After cleaning, honing, lapping, and checking all the parts, I discovered that the valve springs are too soft  Too soft springs is one of the things that can possibly cause burned valve, I certainly don't want to put these back in.  I've ordered replacements from Bruce Kown.  He's actually sending them to me without me sending any money first!  I should get them next week.

5/25/02

The valve springs arrived and although they're used, they checked out OK.  I've got the cylinders all assembled now and ready to go back on the engine.  Now I'm painting and doing minor repairs to various parts like induction tubes, cowling, etc.  I also need to get some new SCAT tube.

8/3/02

Can you believe it's been over 2 months since I touched the plane?  I got a little sidetracked with a job so I had to put off any progress but, now I'm back on track.  Got the cylinders installed today as well as most of the intake manifold.  I brought the cowl home, it needs some repair.  I'm seriously thinking about painting it before I put it back on.  It will look kinda funny until I can paint the rest of the plane, but once all the repairs are done, it will need to be painted.  Might as well paint it the color it will eventually be.

7/1/03

I have the cowling completely stripped now.  The nose bowl has a few small dings in it and a tiny crack.  Repairable but I might just replace it.  New ones are pricey though.  Speaking of pricey, I bought a gallon of Epoxy Primer... 185 bux!  While at the paint store I went through the colors to select the ones I wanted but, I could not decide.  I'm thinking of sticking with blue and white but I'd really like shades that were typical of what would have been used in the 40s.

5/20/07

Life can get in the way sometimes.  After a lot of distractions, I'm finally able to get serious about working on the plane.  Today I took out the seats and removed the ailerons; which are the only fabric covered parts remaining on the plane after it was metalized.

5/20/08

Today the wings were removed and trailered to my home.

5/22/08

Tail surfaces removed and the fuselage was prepped to be towed home.

6/07/08

Towed home.  I took a trailer coupler and attached it with a bracket in place of the tailwheel and towed it home just like any other trailer.  Kind of attracted a little bit of attention.

 

An airplane is a vessel of memories.......