Perkins 4-107 Diesel

The serial number for the engine aboard Botany Bay is 107U42611. From the Perkins shop manual it can be inferred that the engine displaces 107 cubic inches, was built in the United Kingdom, and has an engine number of 42611. The year of production was not incorporated into the Perkins serial number until 1975. The engine and reduction gear weigh approximately 570lb (259kg) not including the V-Drive which weighs something like 60-80lbs. The engine is rated at 48shp (37kW) at 4000 rev/min [high speed pleasure craft], 45shp (36kW) at 3600 rev/min [pleasure craft], and 37shp (30kW) at 3000 rev/min [commercial craft]. The sump requires 4.2 quarts of oil to refill or 5.1 quarts of oil after a rebuild. The cooling system contains 7.8 quarts of coolant. 

The maintenance schedule I follow is:

Every Hour and at startup:
     Check Oil Pressure - Note rapid fluctuations on gauge indicate oil level slightly low, add 1/2 qt oil

Every 8 hours or daily:
     Check Oil Level
     Check Water Level
     Check Gearbox Level

Every 100 hours or 3 months:
     Change Oil and Oil Filter
     Check belt tension
     Check/Replace heat exchanger zinc

Every 400 Hours or 12 months:
     Change fuel filters
     Change gearbox oil
     Replace raw water impeller
     Clean heat exchanger

Every 2-3 years:
     Service Injectors (including two spares)

When I originally purchased Botany Bay she had a 18" x 12pitch fixed three bladed prop and the maximum RPM which the engine could attain in gear with a clean bottom was 2200 rev/min. When I replaced the propeller with a 18" Maxprop I set the prop at 19 degrees (or 11.7 pitch) and can achieve 2700 rev/min and cruise comfortably at 2100 rev/min. I reset the prop to 17 degrees (or 10.4 pitch) and can achieve 3200 rev/min and cruise comfortably at 2600 rev/min which is a bit noisy. I finally settled for 18 degrees (or 11.0 pitch) and can achieve 2900 rev/min and cruise comfortably at 2350 rev/min. As the pitch becomes lower (flatter) the efficiency of the propeller becomes less with the ideal being closer to 12 or 13 pitch. However, the width of the deadwood (back of the keel) results in a desire for a somewhat larger propeller than might otherwise be desireable.

Plan to add a chart of speed vs. RPM for various pitch settings along with maximum achievable RPM for each pitch setting.

Note, however, that with the alternator loading the engine heavily (providing 80 amps @ 14.4V) the engine will gradually overheat if run for extended periods (2-4 hours) heavily loaded. If motoring for extended periods at high speed is required either reduce alternator output or make sure that the batteries are mostly charged before setting out. Normally I simply reduce rev/min by about 200 when charging and don't have any difficulties. 

Plan to add a chart of temperature vs. time with and without the alternator loaded at cruising RPM.

A nice feature of the Perkins 4-107 is it's ability to pass air bubbles in the fuel lines. This is the result of returning a significant amount of fuel back through the return lines. By comparison newer Yanmar engines don't even require a fuel return line but are very sensitive to air bubbles in the fuel lines.

Interesting observation, a new Yanmar seems not to suffer from the sensitivity to air in the fuel. This observation was with a 30HP Yanmar on the Tayana 42 "Wings" which had significant trouble if there was any air in the lines at all. On the other hand, the new 56HP Yanmar in the Northwind 43 "Alegria" seems to self bleed without any trouble. Replaced the primary fuel filters (carefully filling them before installation) and it ran without difficulty, replaced the secondary fuel filter on the engine and it ran for a bit, stopped due to air in the injection system, and with a minimal amount of cranking bled itself and started without any manual bleeding, a significant improvement.

water pump

raw water pump

Phone 206-789-4600. Ask for Larry Stewart of Stewart's Marine Engine and Machine Works. He's got a few older engines in stock and parts for almost anything Perkins ever built. A genuine resource for Perkins owners.

The 2004/2005 winter refit included extensive refurbishment of Botany Bay's engine room. Sound proofing was added as well as hard walls on all sides so that the engine room is now separate from the rest of the aft machinery spaces. Various small projects were completed including:
     - Mill aluminum exhaust manifold to stop persistent exhaust manifold gasket failure
     - Replace exhaust riser, water injection point, exhaust hose etc
     - Paint Engine
     - Burn out heat exchanger
     - Replace oil pressure switch (leaking)
     - Replace oil pressure sender (leaking)
     - Install Murphy Temperature Gauge
     - Install rebuilt starter purchased for return trip from Kwaj
     - Replace engine room fire extinguisher (lost overcharge)
     - Enclose 12V DC electrical panel
     - Install 2 permanent 12V lights in engine room
     - Reroute raw water intake hose out of engine room for better access
     - Rewire engine room
     - Shim alternator to increase load carrying capacity of belt at high load
     - Reverse throttle and shift controls to match new Edson system
     - Replace thermostat (preventative)
     - Replace fuel lift pump (preventative)
     - Moved engine room blower to engine room instead of transom
     - Exchanged engine intake seacock with watermaker seacock
     - Painted engine intake bilge area
     - Replaced all engine coolant loop hoses
     - Cleaned and inspected all engine oil lines (replaced chafe protection)
     - Neutral lockout switch added to starting circuit
     - Engine shutdown solenoid installed
     - Automatic engine shutdown circuit planned for
     - Bilge pump hoses rerouted to aid cleaning and inspection
     - Coolant overflow tank replaced
     - Updated fuel system and started installation of fuel transfer pump

Replacement Oil Pressure Sender: Sierra 18-5899 0-80PSI Replaces Crusader 700425, Pleasurecraft RO20001, Mercury/Mariner 90806, OMC 982650 $32

Replacement low oil pressure alarm switch: Standard Motor Products PS12 Switch/Interruptor/Commutateur $12

Replacement Fuel Pump: ULPK0014 $60, hand written note 7B3

Replacement Belt Gates XL series 9405 (12.5/13mm x 1038mm)

The waterlock is part of the exhaust system, to the left the exhaust gases mixed with raw water coolant come down into the waterlock. As the amount of water increases the outflow exhaust port is covered with water and exhaust  backpressure causes the water to be pushed out of the waterlock, through I high gooseneck to prevent following seas from flooding the engine and then overboard.

Engine Room Fire Suppression is provided by this xx cubic foot FM-??? based automatic fire extinguisher.