Dillon Francis

Custom Design - Manufacturing - Project Management

Propulsion - Transmission


Steerage Systems

Dillon Oberholzer - Tappet Setting

Propulsion Systems

  • Diesel

  • Petrol- Gasoline 

  • Out-Board

Transmission Systems

  • Linear Drives

  • Hydraulic Drives

  • Z-Drives

    Shaft systems

  • Prop Shafts / seals 

  • Rudder shafts / seals

  • Drip-Less Seals



Although I am not a fully qualified mechanic, I have many hours of experience working on and servicing many types of drives and motors.

I have rebuilt Caterpillar motors, Yanmar diesels, Ford Lehman straight six diesel motors, Perkins 4108's as well as Volvo's and BMW diesels.  Outboards only from five to forty H/P. 

Having captained numerous vessels on numerous deliveries and voyages the propulsion systems are always in the forefront of ones mind. As a captain I believe one should be intimate with every part of the vessel you are sailing. Key responsibilities include the correct operation and maintenance schedule for these systems.

I will in the future list my experience within the  sub-categories above with clickable links to the information in new pages. If you have any specific questions as to my capabilities please do not hesitate to contact me directly.

I have normally employed a mechanic for my mechanical departments and service centers but always have double checked the work and parts they have installed.

Boat owners and captains rely on the work performed and expect reliable service life from a job they entrust to a professional marine company. As a boat owner and captain I always make sure these systems are in sea worthy condition prior to leaving my shop.

Ford Lehman 120 HP     (Click for Manual)

Dillon Oberholzer My Twin Ford 135 HP Motors

I ran these motors for 25,000 nautical miles.

Rebuilt one in Panama the other I replaced the fuel injection system in Guatemala.

The velvet drives requires overhaul due to over heating. Kept the props spinning for 3 years.

I had to remove the head in order to take the motor out.



Nice little motors  I have rebuilt 3 of these over the years.

One on the island of St. Helena

One in Florida and one in Seattle.

Folks complain that you cant get part but most engineering and Motor re-builders have pistons and bearings the same specs as OEM parts.

Gaskets can be ordered in kits or fabricated. Today online you can get just about anything.

BMW 1 Cylinder

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Horrible motor.

Rebuilt 2 of these one in Cuba

 One in Cancun

Noisy, jerky pieces of crap.

They were originally made for road working equipment.

Yanmar 3 Cylinder / 2 gm 20


Super little motor. Has problem with the exhaust riser. tends to suck back moisture and causes corrosion in the head.

Have rebuilt 2 of these where all parts and heads were replaces.

 Altered the exhaust manifolds and installed water vapor box

Both jobs done in Seattle when I had my dry dock.


Yanmar 2 Cylinder

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Same as above basically 

 One job done in Seattle one in Panama

 By the time the boats get from the USA to Panama the motors are pretty much shot.

Ordering part down there isn't a problem, just costs a bit and take a little time.

Volvo 3 cylinder


I have rebuilt 2 of these both at Minneford Marina in New York.

 One was in a boat I bpought  the other was for a client who knew I had rebuilt mine and his was tired.



Most new boats are fitted with drip less seals. These however need to be checked and spare seals need to be kept on board.

If this design is not properly lubricated it will over heat and wear out.

Again the lubrication lines need to installed correctly with no kinks and preferably with no tall loops. If the hose is raised into a loop it will cause  air to accumulate and which causes a dry seal and eventual over heating  and seal replacement is imminent. 

Straight forward install, slide it on, clamp it up and off you go.

There are many different manufacturers all with similar operations. Choosing the one that best fits your requirements is really based on availability in your area. Also the spare seals. These should only require servicing every 5 to 7 years. If on a long cruise more often.

There are many different manufacturers all with similar operations. Choosing the one that best fits your requirements is really based on availability in your area. Also the spare seals. These should only require servicing every 5 to 7 years. If on a long cruise more often.

Stuffing box.


A traditional stuffing box style flange is normally made from a flexible rubber tube clamped on to the hull shaft log flange with the other end clamped onto a cast bronze stuffing box which fits over the shaft.

By tightening the stuffing box you are squeezing the seals inside onto the shaft creating a seal. These seals and stuffing box are lubricated with grease. and water.

These are most common in older boats and in rudder shafts. These stuffing boxes require approximately 10 to 15 drips inside the boat is what is regarded as a rule of thum, per minute is the ball park for the tightening of the flange. (based on 2 inch shaft).

You will require spare seal material and make sure your flange has a grease nipple to squeeze new grease in from time to time.

These should be checked every time you get on board and every time you leave your boat !

I have had to re-float a boat because of a leaky seal and batteries with no charge for the pumps.

I like them, understand them and am comfortable with their operation.



Sea-doo - High Speed Flanges


Depending on the equipment that comes installed with your craft, especially a production craft I suggest that you stay with OEM parts. 

Depending on where you are you might have a hassle  in ordering your part but the owners manual should list the part. If the OEM is not available because the part has been dis continued or the company is no longer in business then get in touch with a marine professional who works with these flanges.

The earlier Bombardier crafts were a real pain in the ass. They built their crafts from all sorts of different suppliers. Half of whom no longer exist.


Rudder Flanges


Typical 90's production boat flanges


These flange designs were made for light cruising.

They never worked for long and caused a lot of people a lot of grief if they were cruising on any extended voyages.

The rudder has two flanges and basic seals. One at the bottom and one at the top. The bottom flange take most of the strain and impact from waves and steering pressures either from the action of sailing or the motor and propeller.

The top flange sees about 2o percent of the main  pressure but is required to have a seal. Depending on the location height of the top flange which is a part of the whole quadrant assembly and the steering apparatus,  the top flange has the seal.

This pic shows the total break down of a lower flange assembly.

These are simple systems and normally require quick and simple solutions. 



Rudder Design

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As many different rudder designs for as many different boats there as as many different fudder flanges and seal systems.

Every different rudder design has its own unique flanges and sealing systems. Especially on sailing craft.

Power boats are a little more standard.

Having built and repaired many different boats I have seen my fair share of systems and assemblies. and applied the best of designs to the boats I have built and shared my experiences with the boat owners whose boats I have repaired.

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These are my choice replacements.

Dillon Francis

Custom Design - Manufacturing - Project Management