The 3D84E in your Komatsu PC38UU-2 is getting hard to source. The 3D88 replaces it - same block architecture, same 90 mm stroke, same mounting layout, 1.642 L instead of 1.496 L. We carry it new surplus and rebuilt.
The Komatsu PC38UU-2 is a 3.8-ton class ultra-short tail-swing mini excavator, built for work in the tightest confined spaces where a conventional tail cannot swing.
ENGINE SPECIFICATION. Three cylinder, four cycle, water cooled, vertical in-line. Direct injection, naturally aspirated. Bore and stroke 88 x 90 mm. Displacement 1.642 L (100.2 cu in). Around 36 hp at full rated speed, less in machines governed lower. Dry weight approximately 341 lb (154 kg). Engine as fitted to this machine: Komatsu 3D84E. Production years: 1995-2004. Original rated output: approximately approx. 33 hp.
WHY THE 3D88 REPLACES THE 3D84E.
Komatsu's 3D-series three-cylinder diesels are one family on one architecture - the same 90 mm stroke, the same block design, the same mounting and accessory layout. Only the bore changes:
3D82AE - 82 mm bore, 1.331 L, around 29 hp (Yanmar 3TNV82A)
3D84 / 3D84E - 84 mm bore, 1.496 L, around 33 hp (Yanmar 3TNE84 / 3TNV84)
3D88 / 3D88E - 88 mm bore, 1.642 L, around 36 hp (Yanmar 3TNE88 / 3TNV88)
Because the 84 mm and 88 mm engines are built on the same core with the same mounting layout, the 3D88 is the established replacement where a 3D84E is no longer available - a little more displacement and a little more power from the same footprint.
Before it ships we confirm the mounting points, bellhousing and SAE housing, flywheel, oil pan clearance, PTO and pump drive, throttle linkage and wiring against your machine. Most of that is external and carries over from the engine you are pulling out.
KOMATSU 3D88 AND YANMAR 3TNV88 ARE THE SAME ENGINE.
Komatsu's small D-series diesels are Yanmar TNV engines built under the long-standing Komatsu-Yanmar relationship and badged as Komatsu. The Komatsu 3D88 / 3D88E is the Yanmar 3TNV88: same block, same crankshaft, same 88 x 90 mm bore and stroke, same 1.642 L displacement, same architecture. If your data plate reads 3D88E-3, 3D88E-5, 3D88E-6 or 3D88E-7, that is a Komatsu-badged Yanmar 88 mm three-cylinder.
This matters commercially because it doubles the pool of engines that can be built to fit your machine. We supply both, and we set the core up with the accessories your Komatsu needs.
MECHANICAL OR ELECTRONIC - THIS IS THE ONE THING YOU MUST MATCH.
The Komatsu 3D88 spans two fuel systems and they are not interchangeable. MECHANICAL INJECTION uses a mechanical pump and governor - no ECU, no sensors, no wiring harness to match. This is what most machines in the field run and it is our standard stock. ELECTRONIC / COMMON RAIL is ECU-controlled, fitted to machines built to the later emissions standards. We carry both, new surplus and rebuilt.
The suffix - 3D88E-3, -5, -6, -7 - does not mean a completely different engine. The core is the same across the family. The suffix tells you the emissions tier, the fuel system, and the accessory package Komatsu specified for that machine. The accessory package is the part that can be changed: the bellhousing, flywheel, oil pan and sump, manifolds, alternator and starter position, pulleys, brackets, PTO and hydraulic pump drive and the throttle linkage are all EXTERNAL components. They bolt on and off, and they carry across from the engine you are removing onto the replacement core.
So the working rule is: MATCH THE FUEL SYSTEM, ADAPT THE EXTERNALS.
CYLINDER COUNT. The 3D88 is a THREE-cylinder engine, 1.642 L. The 4D88 / 4D88E is a FOUR-cylinder engine, 2.190 L. Same 88 in the name, different engine. Several PC40, PC45, PC50 and PC55-class machines run the four-cylinder 4D88E, not the three-cylinder 3D88E. Read the data plate - do not go by the machine model alone.
BEFORE YOU ORDER.
Send the data plate off your Komatsu PC38UU-2 - model number, suffix, serial. We will confirm whether you need the mechanical or the electronic version, check the cylinder count, tell you what bolts across from the engine you are removing, and quote you on the correct core.