Renko, my steel trawler, is powered by a Detroit Diesel 4-71, a two-stroke diesel that's been around since the 1930s. When I bought Renko the engine had seized, so it came out, was rebuilt and went back in, and a year later it came out again for a second rebuild with Adrian, a Detroit Diesel mechanic. These topics cover how the engine works, both rebuilds, diagnosing problems, and its fuel and cooling systems.
PHOTO Dangar Marine Boat Guide
How a Detroit Diesel two-stroke works
Open ›A Detroit Diesel two-stroke has exhaust valves but no intake valves. I compare it with petrol two-strokes and four-strokes, showing how the blower pushes air through ports in the cylinder liner and clears out the exhaust.
Rebuilding the Detroit Diesel 4-71
Open ›Renko's 4-71 seized in 2019 and was rebuilt with Adrian, a Detroit Diesel mechanic, then came out again in 2020 to fix an oil leak. Every step is filmed, from removal to the first sea trial.
Diagnosing Detroit Diesel problems
Open ›A Detroit Diesel can lose power or push oil out the breather. A local expert and I trace the causes, rebuild a water pump and oil pump, and try reviving a seized 4-53.
Building, testing and replacing diesel injectors
Open ›Detroit Diesel unit injectors pump fuel to injection pressure and spray it into the cylinder. We build and pressure test a set, timing the rack, then fit N50 injectors to Renko.
Rebuilding a Detroit Diesel fuel pump
Open ›The fuel pump, blower and governor on a Detroit Diesel 4-71 get a full rebuild before the engine's first start, including replacing a cracked blower end plate, recessing seals and setting rotor clearances with feeler gauges.
How an inboard engine's raw water cooling works
Open ›Raw water from outside the boat cools an inboard engine, drawn in through a strainer by a flexible impeller pump and passed through heat exchangers.
Wet and dry exhausts, and installing a dry exhaust
Open ›An inboard engine's exhaust is either wet, cooled by the raw water, or dry, running hot up through the boat to a stack.
Thermal camera engine monitoring
Open ›A thermal camera watches the whole engine, not just the one spot a temperature sender measures. I connect a FLIR AX8 to a Raymarine network, then set monitoring areas and high-temperature alarms.
Merch
PayPal
Amazon