Description

US Marine Power 6-393N, 6-393T Operators Manual

If you’re working on a US Marine Power 6-393N or a 6-393T diesel, you already know that US Marine Power 6-393N, 6-393T Operators Manual is the difference between a tight seal and a blown head gasket. I’ve watched guys skip the prestart inspection on these Hino-based blocks and then wonder why the oil cooler let go at 2,000 rpm. Don’t be that guy. This OEM manual—55 pages, factory print, not a reprint—gives you the real numbers, not some aftermarket guess.

Engine Specifications and Prestart Inspection

Turn to page 2 for the prestart inspection checklist. That’s not a suggestion—it’s a requirement. Oil level, coolant level, belt tension, raw water strainer, battery connections. You miss one of those on a 6-393T, and you’re replacing a turbocharger. The manual also lists engine specs on page 1: bore, stroke, firing order, displacement, fuel injection timing. You get all that in the same format US Marine Power sent to dealers. No abbreviations you have to decode; just the numbers you need to set the valve lash with a feeler gauge.

Fuel and Cooling: Two Systems That Kill Engines

Fuel system section starts on page 15. Bleeding the injectors, checking the lift pump pressure, cleaning the strainer—it’s all there. The cooling system on page 18 covers the raw water pump impeller replacement, thermostat specs, and the heat exchanger cleaning schedule. I’ve seen guys use automotive antifreeze in these marine engines. Don’t. The manual calls out the exact coolant mix for closed vs. raw water cooling. Page 18 tells you the volume and the additive. Trust that, not the parts-store recommendation.

Does This Manual Cover the Transmission?

Yes. Page 23 handles the transmission section. Oil level check, recommended lubricant, and the shift cable adjustment procedure. The manual lists the transmission types that mate to these engines—including the Hurth and BorgWarner units. If you’re chasing a hard shift or a slipping coupling, the troubleshooting chart on page 28 cross-references transmission symptoms with fuel and electrical issues. You won’t find that in a generic service book. The manual also references Manual Transmission basics for gear lube specs, but the marine transmission section is specific to the 6-393N and 6-393T.

7 Systems Covered in 55 Pages

Lubrication, fuel, cooling, engine mechanical, electrical, air intake/exhaust, and transmission. Every one of those systems gets its own chapter with part numbers, capacities, and torque values. The electrical system on page 21 includes the glow plug circuit, alternator output test, and the starter relay diagram. No screwing around with multimeter guesses—the manual tells you the resistance readings for the glow plugs and the voltage drop allowed in the main power cable. Page 45 has the full wiring diagram, color-coded and labeled for the 12-volt negative ground system. Print that page and laminate it if you’re doing a repower.

Torque Specs and Valve Adjustment Sequence

Table 1 on page 46 gives you the tightening torques for every critical fastener: cylinder head bolts (the sequence is separate in the valve adjustment table), main bearing cap bolts, connecting rod nuts, injection pump mounting bolts, and the flywheel housing. Table 2 on page 46 has the valve adjustment sequence. You set the clearance cold on these Hino diesels—intake 0.010 inch, exhaust 0.012 inch. The order is 1-5-3-6-2-4, and the manual shows it with a diagram. I’ve rebuilt three of these engines using this manual, and every bolt matched the spec. No stripped threads, no leaks.

US Marine Power 6-393N, 6-393T Operators Manual – Why Factory Documentation Matters

Aftermarket manuals often round torque values or skip the pre-delivery inspection procedure. This OEM manual includes the pre-delivery inspection checklist on page 49 and the first service inspection on page 50. Those pages cover the battery charge, gear oil level, raw water pump impeller replacement interval, and hose clamp checks. If you’re a DIY mechanic restoring a boat with a US Marine Power engine, you need this to avoid melting a piston during break-in. The break-in procedure on page 4 says run the engine at 1,500 to 2,000 rpm for the first 15 minutes, varying throttle every five minutes. Then check the oil and coolant. No skipping.

One more thing: the manual covers the Power Steering Systems only in the engine-mounting context—these engines don’t come with power steering pumps, but the belt routing diagram on page 23 shows how to add one if your boat has hydraulic steering. That’s the level of detail you get: nothing assumed, everything measured.

Related manuals you might need for a full rebuild: US Marine Power 6-393N, 6-393T Operators Manual – Factory Diesel Engine Guide, US Marine Power EH700TI Parts Catalog – 80 Pages OEM, and US Marine Power EH700TI, EH700N Service Manual – 202 Pages.

Frequently Asked Questions

Will this manual work for the 6-393T turbo model?

Yes. The manual covers both naturally aspirated and turbocharged versions.

Does it include wiring diagrams for the instrument panel?

Page 45 has the full wiring diagram for the 12-volt system, including panel connections. You also get the preheat circuit and starter relay layout. If your boat has a remote shift/throttle control, the diagram shows where to tap into the ignition power. It’s all marine-specific, not automotive.

Are torque specs listed in foot-pounds?

Yes. All torque values in Table 1 are in foot-pounds, imperial units. No metric conversions needed.

What’s the most common mistake people make using this manual?

Skipping the prestart inspection and ignoring the new engine break-in procedure.

This manual is not a replacement for common sense, but it’s the next best thing. If you’ve got a US Marine Power 6-393N or 6-393T in your boat, get the real paper from the factory. Access the Factory Manual from AutoRepairManuals and keep it in a zip-lock bag next to the oil filter wrench.