Inside IYRS 

Spring has arrived and with it a new area of excitement for System students.  This month we will transition from engine maintenance and repair to marine electronics.   Marine Electronics will cover the installation and power requirements for instruments such as: electronic fluxgate compass, VHF radio, GPS chart plotter, radar, depth sounder, autopilot, boat speed/ ultrasonic wind anemometer, and fish finder.  Installation methods for both sail and power boats are covered in lecture.    Students learn some of the developmental history of these devices and the evolving electronic language that they use to communicate with each other.  NMEA 2000 is the newest form of this electronic protocol. IYRS instructor John Stier walks students through the finer points of the NMEA 2000 network and installation procedures.  Lab covers the installation of the equipment at a portable helm station. System power requirements are calculated and sub-panel breakers are installed.  Lastly, students design a network to allow helm stations to “talk” to each other. But, before we jump into a new subject lets take a minute to reflect on some of the projects that students have been working on.  

For the past several weeks, teams have been working hard to repair and rebuild various engines, generators, and transmissions.  Lecture has covered everything from project management to customer service.  Projects range in size and scope.  Repairs are carried out, and time sheets are kept by each student.  The lab simulates real life experience and expectations.  Students are challenged by our instructors to diagnose problems and explore possible causes.  Repairs that are typically not performed in the field are discussed, such as a “get home situation.”  Specialized engine rebuilding tools are demonstrated and their usage explained in great detail.  As students complete their mechanical practicum projects, final reports and labor hours are recorded and submitted to our clients (the IYRS instructors).  Any additional time left in the day is allocated to buttoning up Renegade.  IYRS instructor Kevin McKiernan rallies the men to complete the remaining final touches and keeps work on track.

In this segment of the course, students have learned how to implement a project plan and submit R.O.’s (requisition orders) for parts.  Procedures for rebuilding our project engines are outlined by students and each student is expected to contribute to the project tear down and rebuild.  

 So what happened to those projects we were talking about last time around?  Here we see the old two cylinder Volvo that was completely torn down to the engine block.  This engine was rebuilt with parts from another similar engine and dubbed “Frankenstein,” by the guys rebuilding it. 

She eventually ran with some exciting results. 

In this photo we see a new fuel line that was fabricated to a mirror image of the one next to it.  Fuel lines are made a specific length to ensure that the proper amount of fuel is delivered to the fuel injector at a precise amount of pressure in order to achieve the correct atomization (of the fuel) within the cylinder. 

The Universal Atomic 4 gasoline engine pictured here had a compression problem with a bad exhaust valve.

We ordered a tool to re-cut the valve seat

and then we lapped the valve and the new valve seat together to assure the two surfaces properly mate.

Finished product:

We use a special clamp to reinstall the valve springs and the valves.

Small tappets are inserted along the shaft of the valve and when the pressure is released from the spring the downward force holds the valve in place.

This engine also had a damaged fuel pump that we thought could be easily repaired in the shop.

As it turns out the housing was badly twisted and we had to by-pass the fuel pump altogether.  An electric pump was installed,

and the engine was reassembled with a new rear main seal and a fresh head gasket.  Moyer Marine offered technical support throughout the build.  We tried to install a new thermostat for this engine but discovered that the housing was badly corroded and needed to be replaced.  For now, these repairs are all that we can squeeze into the budget for this project.

Another interesting mechanical practicum exercise that we were following was the Entec West single cylinder diesel generator.  We rebuilt the fresh water/ raw water cooling pump on this engine.

Then we had to isolate the compression loss problem that troubled this engine.  Not too hard to do with a small one-banger (a single cylinder engine) on our hands.  We removed the head

and cleaned the copper head gasket.  Next we removed the rocker arms to access the intake and exhaust valves.

Like the Atomic 4, we use a clamp to compress the springs and remove the tappets that hold the valves in place.  Once removed, the valves are inspected for wear and measured with a Digital Micrometer to verify manufacturers’ suggested specifications.  Too much wear and the valve will have to be replaced.  Our valves are consistent with the mfg.s’ specs so we move forward.  The valves are allowing air to slip by so we decide to check the mating surface of the valve seat.  A dye is sprayed onto the cylinder head and the valve is then inserted with some fine lapping compound on the edges of it.

A few passes with the lapping compound reveals that the surface of the valve is only making complete contact with 60 % of the valve seat.

We use coarse lapping compound to bring the two surfaces together more.  A final pass with the fine lapping compound polishes the finish and assures us a complete seal.

Finished product:

The engine is then reassembled and tested. 

Upon rebuild it is discovered that we have no governor to maintain 1800RPM to satisfy the generators requirement to make usable 60 Hz 110AC current.  My teammates Max and Ross cleverly design a rod and spring to keep pressure on the throttle when a load is placed on the generator.  In essence the spring will force the throttle back to 1800 RPM when the load is removed.  Amazingly, when tested it,

the governor worked just as planned.  

Remember the straight six International Harvester Engine that was sent out to the machine shop to be re-bored?  We got the engine back and it has undergone a complete transformation.  More on that engine next month.  For now here are a few teaser photos for the Silver Diamond die hard’s out there.  The engine has had the cylinders re-bored and the deck surface machined.

The cylinder head also had new valve guides installed and it’s mating surface was re-cut and polished.

The main drive shaft was retooled and the new pistons were installed.

Some assembly required…In these photos the drive shaft and the new bearings are measured to check tooling tolerances.  A tiny strip of thin plastic with a known mass is inserted between the bearing and the shaft.

Then the saddle is torqued to manufacturer’s specifications. Next you remove the saddle and measure the width of the plastic strip.

Our Ford Volvo Penta marinized 302 that we saw last month has had the freeze plug installed.

The thermostat housing has been welded back together 

and the exhaust risers were cleaned out.  Here is a look at one side with the exhaust manifold removed.

The exhaust had a lot of debris in the cooling side of it and here you can see just how bad saltwater cooled engines can corrode.

that was broken down by some students to replace a cylinder liner.  The electronic fuel injector was clogged, so when the high pressure in the fuel lines forced fuel into the cylinder past the clog, it ignited and became a virtual blow torch.  This in turn melted a hole through the liner.  For practical experience, all of the cylinders were inspected by removing the cylinder head, and taking out all of the pistons.  This is accomplished by draining and removing the oil pan, and then unbolting the connecting arms from the drive shaft.

This is exciting work for everyone to see in the shop.  The cost for these engines to be rebuilt far outweighs the cost of new one, so chances are this task would only be performed by a specialized rebuild shop.  It is common practice in the industry today to recommend a repower in this situation.

One of my favorite gasket rebuilds was this head gasket

that my friend Chris made out of 16 oz. copper sheet.  This was all done by hand !  Great job Chris.  This gasket was used to reseal the head on this Onan generator

that was donated to us from New England Boatworks.

Here is a look at how to test spring tension with a drill press.  In these photos my teammate on the Ford/Volvo project, Dan, demonstrates the procedure.  

Step one,

find a free drill press to set up the scale on.  

align spring with drill press chuck.  

compress the spring and record the pressure on the scale.  

At the close of the mechanical practicum, reports are submitted to our instructors.  Reports include the labor hours and parts used to complete the repairs.  A detailed analysis of the project is also submitted, as well as an invoice for the customer to review.

The battery is charged up and placed in the new battery box.