The 3126: Don’t call it a small diesel.

At Caterpillar, there’s no such thing as a “little” diesel. The 3126 is the same durable engine police patrols and commercial fishermen depend on every day. It features slim, in-line 6-cylinder configurations that allow easy twin engine installation — even with the smaller footprints of 30-45 ft. (9.1-13.7m) boats. And thanks to 300 - 385 bhp (224 - 287 bkW) of diesel power, you do more than just froth up water to stern. Big-engine features include large camshafts, two-piece articulated pistons, large oil coolers, roller followers and heavy-duty unit fuel injectors. Plus, the new, more robust turbocharger and other improvements mean better reliability, durability, throttle response, boost and acceleration. It’s a seri-ous engine to help you have more fun cruising and fishing.

The 3126B: Electronically superior.

Any engine accelerates. With 420 - 450 bhp (313 - 336 bkW) of diesel power, the 3126B exhilarates. It also reduces emissions, virtually eliminates smoke and soot and retains the mechanical 3126’s low 3.96 weight-to- power ratio (2.41 kg/bkW) and far-ranging fuel use rates. State-of-the-art electronic control — and Caterpillar’s patented hydraulically-actuated electronically-controlled unit injector (HEUI™) fuel system — make it all possible. HEUI provides full fuel-injection pressure at less than half the engine’s rated speed and makes fuel delivery timing completely independent of engine rotational speed. A new turbo design also delivers exceptional low-end response and quiet operation.

Whether boats help you earn a living, or live a little, engine performance is integral to your success. At Caterpillar, this is what motivates us to build marine engines to the highest standards of quality and performance. And, what motivated us to update the 3126 engine. The diagram at right shows some of the most important modifications we’ve made. It does not show the extensive lab testing, or the hundreds of hours of real-life testing, we’ve devoted to ensuring these updates are effective. Nor does it show the enormous capital investment we’ve made to improve quality, reliability and throughput at our 3126 engine facility in Greenville, North Carolina, USA. In fact, the Greenville project represents the largest capital investment by Caterpillar worldwide in all of 1997. To learn more about the Cat 3126 engine updates, talk to your local Cat marine dealer. You’ll like what we’ve changed. And, what we’ve left the same.

A new, more robust turbocharger with steel alloy turbine wheel greatly improves overall engine performance. Throttle response, boost and acceleration all show marked improvement. Boats come out of the water quicker, time to plane is shorter, and exhaust soot is virtually non-existent.

An improvement to the water pump impeller enables the water pump to more effectively handle air entrained within the water, improving coolant flow. Better cooling means less stress on components, including the manifold.

To ensure stricter quality and process control, the exhaust manifold is now cast in a Caterpillar owned and operated foundry utilizing a stronger “ductile” iron which better withstands thermal stress.

Intake and exhaust valves now utilize Pyromet, a nickel-based super alloy, capable of handling the high temperatures and corrosive atmosphere of marine applications. This, together with the addition of tapered, chrome-plated stems, dramatically improves strength and corrosion resistance.

Download Specifications for each of the following models in Acrobat PDF files.

3126 - 300 HP 3126 - 350 HP 3126 - 385 HP 3126 - 420 HP 3126B - 420 HP 3126B - 450 HP Return to Caterpillar Index