Genuine Tohatsu MD40B MD50B TLDI Cylinder Head 3Z5B01091-0

GENUINE TOHATSU CYLINDER HEAD FOR 40/50 HP TLDI

Genuine replacement cylinder head for selected Tohatsu and Nissan 40/50 HP TLDI direct-injection two-stroke outboards. This is a major powerhead component for the 697 cm³ three-cylinder engine family and must be selected by complete model and serial number.

KEY FEATURES

• Genuine Tohatsu / Nissan Marine powerhead component
• For selected MD40B, MD50B, NSD40B and NSD50B TLDI engines
• Current replacement for earlier cylinder-head reference 3T5B01001-0
• Designed for the 697 cm³ inline three-cylinder TLDI powerhead
• Sold as one cylinder head; related service parts are separate unless specifically shown

ENGINE TECHNICAL SPECIFICATIONS

• Engine family: TLDI low-pressure direct-injection two-stroke
• Rated output family: 40 HP / 50 HP
• Cylinder arrangement: inline 3-cylinder
• Displacement: 697 cm³ (42.53 cu in)
• Bore × stroke: 68 × 64 mm
• Cooling: water-cooled with thermostat
• Tohatsu OEM reference: 3Z5B01091-0
• Superseded reference: 3T5B01001-0

VERIFIED ENGINE COMPATIBILITY

• Tohatsu MD40B TLDI — verified in the 2006 cylinder/crankcase catalogue; 3Z5B01091-0 is shown from serial 011601XC onward
• Nissan NSD40B TLDI — verified in a 2004 cylinder/crankcase diagram
• Tohatsu MD50B and Nissan NSD50B TLDI — selected 697 cm³ 40/50B-family versions; confirm the serial-specific diagram

Earlier production may show cylinder head 3T5B01001-0, which the parts catalogue lists as superseded by 3Z5B01091-0. Serial breaks differ by market and model suffix, so this supersession must still be checked against the engine identification plate.

Not a universal 40/50 HP head: do not order for carburetted M40/M50, MFS four-stroke or later unrelated engine families unless the exact catalogue lists this reference.

WHAT IS NOT INCLUDED

This listing is for the cylinder-head component only. The cylinder-head gasket, head-cover gasket, cylinder-head cover, thermostat, thermostat-cap gasket, bolts, seals, anodes and internal components are not included unless they are specifically visible and stated as supplied.

CHECK BEFORE ORDERING

• Confirm the full model: MD40B, MD50B, NSD40B or NSD50B—not horsepower alone.
• Record the complete serial number, including its letter suffix.
• Check the cylinder/crankcase diagram for the exact production range.
• Confirm either 3Z5B01091-0 or the superseded 3T5B01001-0 at the cylinder-head position.
• Determine which gasket, seals, thermostat parts and fasteners are required for the rebuild.

INSTALLATION AND INSPECTION

Cylinder-head replacement requires factory tightening sequences and torque values. Before assembly, a qualified technician should inspect the block deck, cylinders, sealing faces, threads, cooling passages and the cause of the original failure. Use the service manual for the exact model and serial range.

FREQUENTLY ASKED QUESTIONS

DOES THIS FIT EVERY TOHATSU 40 OR 50 HP OUTBOARD?

No. It is for selected 697 cm³ three-cylinder TLDI MD40B/MD50B-family engines, not every 40/50 HP model.

WHAT DOES THE OLD NUMBER 3T5B01001-0 MEAN?

It is an earlier cylinder-head reference listed as superseded by 3Z5B01091-0. Confirm the supersession for your exact serial number before ordering.

IS THE CYLINDER-HEAD GASKET INCLUDED?

No. The gasket and other rebuild parts are separate unless specifically stated in the listing.

WHY IS PROFESSIONAL INSPECTION IMPORTANT?

A failed head can be the result of overheating, detonation, corrosion or sealing damage. Installing a replacement without correcting the cause can lead to repeat failure.