Tuesday, July 26, 2011

Replacing the chain oil pump on a Stihl 034

While running my chainsaw, I noticed the chain was getting tight on the bar, and not operating free.  As I examined it closer, I found the bar was not being oiled. It turned out that my oil pump had stopped working.  Here's how to replace it.

  1. Get out your tools.  The 034 comes with a rudimentary tool kit that has almost everything you will need.  A flat head screwdriver, a number x torx, a 5/8th socket, you will also need a small flat head screwdriver, and a pair of needle nose pliers.
    The next four steps are pretty routine.  If you have never removed these parts, this guide is not for you.
  2. Remove the cover from bar, and remove the bar and chain.  
  3. Remove the air intake cover from the back of the saw (quarter turn on the locking knob and pull up).
  4. Disconnect the spark-plug wire (pull straight from plug).
  5. Remove the top cover (flat head screwdriver to loosen the screw on the top).
  6. Remove the flat head screw that holds the metal chain guide plate on, and remove the plate too.
  7. Drain the oil from the bar oil tank by removing the cap, unhooking the retaining chain, and pouring the oil into another container.
  8. Remove the two torx screws holding the plastic cover around the flywheel, and lift the cover off.
  9. Pry the lower cover up from near the bottom -- carefully.  It has a post on it that presses into a hole, so it you pry off to the side, you risk breaking this post.
  10. Using a small flat head screwdriver, remove the snap-clip that holds the sprocket drive in place.
  11. Lift off the washer and sprocket.
  12. Lift off the flywheel.  
  13. Remove the strap that stops the flywheel.
  14. Remove the spark plug.
  15. Now comes the tricky part.  To remove the clutch wheel, you have to stop the piston from going up and down. Stihl makes a special tool that is inserted through the spark plug hole and blocks the piston from moving.  We are going to use a clean (emphasis on clean) rope.  Thread a bunch of the rope down into the cylinder to fill it.
  16. The clutch has left-hand threads, so turning it clockwise will cause the piston to block against the wad of rope in the cylinder and then loosen the clutch.  
  17. The assembly that sits below and has a loop around the crankshaft is the oil pump.  Remove the nylon worm-drive gear from the center by turning it clockwise.
  18. On the bottom of the saw, turn the oil feed all the way in.
  19. Remove the two torx screws from ring on the oil pump that goes around the crank shaft.
  20. The pump is pressed down into a ring recessed into the crank case.  You have to pry it out.
  21. The pump comes with a new oil line so remove the old one -- and you are going to destroy it getting it out. Start by locating the brass grommet that fits inside the end of oil line where the oil is supposed to be coming out.  I had to dig at mine pretty aggressively to get enough of it exposed to grab it with a pair of needle nose pliers and pull it out.  
  22. Pull the oil line and the oil pump out.  Yay.  
A chainsaw is a pretty dirty environment.  Spend some time cleaning things up before you start putting it back together.  The grommet that creates the seal between the pump and the reservoir is really a flange on the end of the oil pickup tube.  I suggest removing it as well and cleaning it out with some compressed air.


  1. Clean out the grove in the crank case where the oil pump presses in. This is important because if you don't the oil pump may not seal and pick up oil from the reservoir.
  2. Feed feed the new oil line into it's passage way.
  3. Put the two torx screws in to hold the oil pump in place.  Tighten them incrementally, alternating to minimize binding, but making sure the oil pump is securely seated.
  4. Put the thrust washer back against the crank case.  
  5. Put the bushing on the crank shaft. 
  6. Thread the worm gear back onto the crankshaft.
  7. My pump came with what looks like a long spring for a pen.  That spring is to keep the oil line from kinking.  Slide it inside the oil line.  Press the new brass bushing into the end of the oil line to the line in place.   
  8. Thread the the clutch on to the crankshaft (remember it is left-hand threads).
  9. Slide the roller bearing onto the crank shaft.
  10. Slide the flywheel onto the crankshaft over the roller bearing.
  11. Put the sprocket back on.
  12. Put the thrust washer back on.
  13. Put the snap clip back on.
  14. Put the strap that stops the flywheel back on (make sure the break is disengaged).
  15. The rest of the reassembly is just reversing the remaining steps.
  16. Before putting the bar back on, clean the chain grove in the bar.  Also, take a look at where the oil line feeds the oil through the small hole in bar and clean it out too.

Sunday, July 17, 2011

Most Active Blog Post.

Out of Tragedy comes Triumph.

OK, that's a bit over-dramatic. The blog post I get most comments on is the one about replacing broken mirrors on my truck.

It is nice to know I have helped others in some small ways. I took great joy in the comment from the Juanita Williams who was able to repair her husbands truck. I am excited every time someone says thanks. I figure maybe one in 10 folks comment, so the 40 odd notes of appreciation means somewhere I have helped 400 people.

But today's note elevates the post to a new high... "The instructions that came with my after market mirror consisted of ... the web address of your blog"

Yay! I'm famous!

Saturday, July 16, 2011

Why I Fly (Chapter 16)

Last week, I was on a business trip to CT. I knew I also needed to spend the weekend on the east coast, so I decided to get checked-out for an airplane rental and take the plane on a quick tour of New England. As a result of casual conversation in the office, I decided to get checked out at Blue Sky Flight at Bridgeport's Sikorsky Memorial Airport in a Grumman AA-5.

It was from this airport the US cranked out F4U Corsairs, the planes featured in the 70's TV show Baa Baa Black Sheep. On my first visit to the airport there was one mounted as a popsicle near the passenger terminal's south entrance. The plane was removed a while back for restoration.

Blue Sky is on the north side of the airport, next to a little dive bar called the Windsock Inn. I stumbled onto the Windsock a couple years back, and try to go grab dinner there on each of my trips just to experience the local color and home cooked meal.

I made am appointment for 6 PM Tuesday night, and met my flight instructor for the week, Sheila Murchan. Getting checked out for a new plane at a new flight school can be kind of a pain. It is not like renting a car where having a license for a state 3,000 miles away and being over 25 years old is good enough. Nope, every flight school needs to confirm that the FAA approved Designated Pilot Examiner, and the list of flight instructors that came before them measure up to their standards. And every rental facility's standards are different.

How different? Here are some examples:
  • I was holding the airplane's check list in my left hand, progressing down the checklist using my thumb to mark my progress. I reached across with my right hand to hit a switch and was reprimanded for not using my left had since it was closer.
  • To control my speed during taxi, I reduced the RPMs below 1,000 rather than applying the breaks.
  • On a simulated engine failure, I flew an arching right turn onto the runway rather than turning immediately over the runway and slipping for altitude...
  • Oddly there was no handbook test to assure my familiarity with the aircraft systems and specifications.
Sheila knows the intricacies of the Grumman AA-5, and I had to fly it to her standards to get her permission to rent it, but I'm not convinced that any of her training on general flying is any better than what Rev, Lewis, Sean, Mike, Chuck, Patty, Howard, Bob (you get the idea) had taught me before.

Other than area orientation and the specifics of the AA-5 such as climb-out and approach speeds, I was frustrated by much of the training. Yet I know Sheila's goal is to keep me and the airplane safe, so I listened and perform the flight according to her standards.

After 2.4 hours of flying in circles, I was approved to fly N11840 on my own. Wednesday night I picked up the charts and manuals needed to navigate the New England area.

Friday evening back at the hotel, I found a large table on the edge of the lobby where I studied the charts and manuals to familiarize myself with airports, frequencies, towers, altitudes, landmarks and headings.

Saturday morning, I updated my flight log for the current winds aloft, and called flight service to get a weather briefing and file my flight plan. Flight service is this great free service provided by the federal government. Pilots can call these guys any time, day or night, and get a 10 to 30 minute weather briefing on any arbitrary flight route in the US. For free. As often as we want. And we are encouraged to do so by regulation. But being a limited government guy, I wonder what part of the constitution empowers me to expect my neighbors, friends, and relatives to pay for this service for me. Heck, I wonder what part of the constitution authorizes the Air Force. But I digress.

The weather forecast is for intermittent low clouds in the morning, and improving as the day goes on. Good enough for me. The airport is clear, and I'm out for a joy ride. If things go bad, I can turn around and come back.

The plane's preflight reveals no surprises and soon I am at 3,500 feet east bound towards North Central State Airport, Rhode Island.

Summertime in New England is marked by the three Hs. Hot, Humid, Hazy. Today will be no exception. Even where the sky is clear, forward visibility is limited to about 20 miles.

The intermittent low clouds started showing up about 10 minutes out of Bridgeport. I considered climbing to stay above them, but I had no assurance I would be able to find a hole to get back under then at my destination, so instead I descended to 2,000 feet and skittered along below them.

Being unfamiliar with an area, it takes a while to be come proficient with identifying landmarks, and eastern CT is markedly void of landmarks I could recognize. Navigation then becomes a process of heading, speed, and time.

As the time for the airport's appearance neared, so did the Providence class C airspace. Class C airspace typically surrounds smaller commercial airports, or places served by the spokes of the hub-and-spoke transportation system. Their controlled airspace usually only extends out ten miles, but they often like some warning and ask for contact within 20.

I switched frequencies, and called up Providence Approach. They informed me there was parachute jumping in progress at my destination airport, and that it was 4 miles to my south east. I was glad they told me. I was still expecting to see it to the north east, and I had no desire to collide with a falling body. I circled to the north of the field until the radio reported the parachutes were open, and then entered into the pattern. About the same time the jump plane also entered the pattern on the opposite side of the field.

I was so busy looking for the parachutes and the jump plane, I ended up high on final and had to go around. By my second pass things were less busy, and I landed, taxied back, and departed. One new state down.

The plane climbed out quickly, and I turned north. I was becoming accustomed to finding landmarks as the distance between me and Boston's class B airspace rapidly decreased. Class B surrounds BIG airports, is usually about 30 miles in diameter, and shaped like an inverted wedding cake, with a smaller inner tier near the ground and progressively larger layers extending up to 10,000 feet. Boston matches this pattern pretty well.

I dial up Boston Approach on the radio to negotiate a path to the west of downtown, just below their airspace, and just above one of the smaller outlying community airports. The controller assigns me a squawk code, notifies me of approaching traffic and clears me to operate through the Class B. This is a sign of an experienced controller. He knows where I am, where I am going, and how I plan to get there. And he gives me some of his airspace to make my life easier. Thank you Mr Boston Approach Controller.

I got a nice straight in approach into Lawrence MA, where I landed, taxied back, and departed. Done. Two states down.

I followed a heading north paralleling the shoreline of the Atlantic Ocean up to Sanford Maine. This was the section I was most concerned about weather wise. When I had checked the weather in the morning, Sanford was reporting 400 overcast with clearing as the day progressed. By the time I arrived there was no significant sky-cover. I made a left base entry I to the pattern, and landed long. I taxied to the other end of the runway where I parked the plane. At Southern Maine Aviation I got a new baseball cap, and had the fuel tanks refilled. And ate a cookie. Three down, and the first time I had set foot in Maine.

The plane climbed quickly to 4,500 feet. The AA-5 is a spritely little plane. At 90 kts it climbs at right around 1,000 feet per minute. This particular plane has been upgraded with a LoPresti Speed Merchants cowling and wheel pants to reduce drag, so It cruises level at a comfortable 140 kts. The distance between Sanford Maine and Keene, New Hampshire is quickly scrubbed away.

The plane descended across the airport and entered into a left down wind 45 for entry into the pattern. I rolled out onto the taxi way, zig-zagging over the crossing runway to the fuel pump. Here I found another AA-5 being refueled. It took very little effort to get one of the occupants to take my picture. Four states, and my first visit to New Hampshire.

The flight from Keene to Bennington VT drew me further inland from the coast. There were plenty of lakes, rivers and roads to mark my path. I was receiving flight following, and the controller had me swing south a little to avoid a parachute jump zone. I crossed over some wind generators on a small ridge of what might be called mountains, and maneuvered to land. At Bennington, there is a 300 foot tall monument that looks about like the Washington Monument, but for some reason it pokes up into the sky right where I am turning from downwind to base. I'm guessing the airport location committee and the monument location committee had no common members.

There is a bit of a cross wind here, but just one runway, so I roll in a bit of crab into the wind, and the transition to a left wing low slip. I floated a bit, but the plane still set down on one wheel with plenty of space to stop. I found a place to park, and the airport manager came out to greet me. "The EAA is giving away burgers and hot dogs on the other side of those hangars," he say as he chocks the left main wheel. I walk across the ramp at my third new state of the day only discover the grill has been put away, so no burgers for me, just a soda. I have a picture taken, I take a couple pictures, and check off landing in my fifth state.

Back in the sky, I follow the ridge line to my left and Hudson River to my right in what seems like the longest 40 minute flight ever. The terrain reverts back to the featureless ground that eliminates landmarks to gage forward progress. Dutchess County Airport comes into view, I contact the tower and make a right base entry for landing. Again I float long. And I land in my sixth state of the day.

The final leg back to Bridgeport is boring, the pattern is full when I get there, and I end up third for landing, with takes me far out over the Long Island Sound before turning onto final. This is my seventh landing of the day, back to where I began.

A tour of New England, set foot in three new states, landed in six new states, and experienced a good little plane to boot.