Thursday, October 27, 2011

Honda Foremen

I had Honda Foreman in the shop recently with an oil leak.  The leak was at a faulty seal on the output shaft coming out of the front of the engine.  The red arrow points to the spot where the lip of the seal is distorted.

To replace this seal the front drive shaft needs to be removed.  The drive shaft has splines on each end and "floats" between the engine and front differential.  The mounting bolts for the front differential are removed and this allows the diff to move forward about 2 inches.  Once the differential is moved forward the drive shaft will slide right out. 

Once the drive shaft is out of the way I used a pick to pry the old seal out.  On small seals like this one it is normally easy to pry them out.  Larger seals may be stuck tighter and require a little more work to get out.  I have a couple of examples of this here and here.

Once the old seal is out it is a simple matter to clean the parts up and press the new seal in.  A small seal like this can almost be pressed into place by hand.  It only required a few light taps with a small hammer to seat it.  When driving it in you must make sure that is not bent or distorted. 

Tuesday, October 25, 2011

Arctic Cat 366 ATV

I have an Arctic Cat 366 ATV that had a faulty ignition switch.  For the last few month I have had to wiggle the key around to make the machine turn on.  It gradually got worse, until it would not work at all.  I assumed that there was a bad electrical connection in the switch.

I removed the large plastic nut from the switch, unplugged it from the wiring harness and brought it to the workbench.

Before I took the switch apart I marked both pieces in case there was any confusion about how they go back together.  I have found that a silver Sharpie works great for marking things like this.

When I pulled the switch apart the corrosion was obvious.

I used a small wire brush to scrub the corrosion off the copper contacts.  Some of it was very hard and required a little scraping with a dental pick type of tool.

Before reassembling the parts I coated the contacts with a little silicone dielectric grease.  This stuff is great for preventing corrosion, I put it on almost every electrical connection.

Once I reinstalled the switch the machine worked fine.

Saturday, October 15, 2011

Teller Headstart Water Pump

The Headstart building in Teller has it's own water system with a pump to provide pressure to the building.  The setup is similar to having an on site well, but in this case the pump draws from a large storage tank.

Recently the pump quit working, when I inspected it I discovered that the impeller was broken.  I suspect that someone let the water tank run dry and left the pump running for too long.

Normally you can replace the impeller on these pumps easily, but on this one the heat wrecked the impeller and also some of the other internal parts. When I checked on parts there was going to be a long lead time and a lot of shipping cost to get them from the lower 48.  Luckily I found a complete pump and pressure tank in Nome that was an exact replacement.

The first thing I found in the box was a set of instructions that tell you to stare directly at the tank if  it explodes.  There was also a picture of a snake biting someones hand, or maybe that was something about electrical safety.

Since the new pump was a direct replacement all I had to do was switch the piping over from the old to the new unit.  In different parts of the country there are several types of pipe that are commonly used.  In this area potable water systems are normally plumbed with brass.  Brass is nice to work with and is very corrosion resistant.

Threaded plumbing connections need some kind of sealant on the threads.  Teflon tape works well for potable water systems.  Put a few wraps around the pipe and screw them together.  Teflon tape seals well and allows the joints to be taken apart easily if repairs need to be made.  There are also many different types of paste or dope for sealing pipe joints.  These also work well, but some of them harden with age and can be very difficult to take apart later.

Some of the connections in this system use unions.  A union allows you to put the pipe together without having to spin the assembly around.  The seal in a union relies on a cone shaped fitting pressed into a tapered seat.   

The arrow in the above photo points to the location of the tapered seat on the lower half of the union.  In a union the threads are only used to force the two parts together, they are not part of the sealing surface.  Because of this there is no need for a sealant on the threads.

Here is the complete union on the top of the pump.  In this photo you can see the Teflon tape on the pipe threads and the hex nuts of the union with no Teflon.

This pump assembly is connected to the pressure tank with a compression type packing gland with an o-ring in it.  Whenever I put an o-ring assembly together I like to coat the surfaces with a little bit of silicone grease.  This makes the parts easier to assemble and should keep things from sticking if it needs to come apart later.

The last step is to connect the wires to the pressure switch.  This is a very basic 110 volt connection, a green ground wire, a black hot, and a white neutral.

Here is the completed installation.

Sunday, October 2, 2011

Arctic Cat 1000 TRV H2

A friend brought over an Arctic Cat 1000 TRV H2 with a broken drive belt.  This is Cat's big top of the line ATV, with a twin cylinder 1000 cc motor, two up seating and all the fancy extras.  He had already purchased a spare belt and I thought that it would be a quick easy job.

When I pulled the belt cover off and removed the debris from the old belt I found a small piece of plastic and a metal key for a shaft.  Obviously there was more trouble than just a broken belt.  I removed the secondary clutch and discovered that the helix was cracked.

This first photo shows the clutch on the work bench with an improvised setup to compress the spring.  I used a piece of all thread and a few metal scraps to compress the spring enough to remove the snap ring.

Here is the broken helix.  You can see that the part cracked right at the corner of the groove for the keyway.  This is a classic example of a failure at a stress concentration.

This machine has a powerful engine on a large and heavy chassis, I wonder if the Arctic Cat engineers did not design a drive system that is tough enough to handle it?