Komatsu D80P-18, D85A-18 and D85P-21: pumps and serial changes

D80P-18 and D85 dozers: distinguish the drive and engine installation

A D80P-18 and a D85A-18 can appear close in an engine-power comparison while requiring different pump and drive information. International FPA’s replacement-pump chart illustrates the distinction: its D80P-18 row places FAL 040 in the main-clutch column, while the D85A-18 row places that designation in the transmission-pump column. Both rows list FAR 063 for steering.

These are the replacement manufacturer’s application descriptions, not a Komatsu approval or a guarantee that an unidentified pump will fit.

Inspect the mounting and the old pump’s identification before ordering. FPA describes special flanges on its replacements and identifies a separate main-hydraulic-pump column. A steering-pump description therefore should not be used as an implement-pump specification.

The chart helps explain why a parts advertisement that merely says “D80/D85 pump” is incomplete.

D85P-21 service information starts with the serial

Komatsu shop manual SEBM034511 covers D85P-21 serial 3001 onward. The D85A-21 and D85E-21 entries on its cover begin at 35001, a different serial sequence. Copy the complete model from the plate.

An A-series serial boundary cannot be transferred to the P machine just because both appear in the same book.

The cover identifies both S6D125-1 and S6D125-2 installations and directs engine work to the separate engine manuals. The 125-2 engine specification gives a six-cylinder arrangement with a 125 mm bore, 150 mm stroke and 11.04-litre displacement for the relevant dozer applications. Match the installed engine before applying an engine rating or ordering internal parts; the retained older catalogue’s displacement entry is not a substitute for that identification.

Why one D85P-21 test value does not cover the whole production run

The original PM-Clinic form PMEB100300 divides transmission modulation and reducing-pressure references at D85P-21 serials 3146/3147. It uses a later division, 3688/3689, for engine-speed and oil-pressure references. Those are separate changes.

A service record needs the relevant serial range beside each result, rather than a single “D85P-21 checked” note.

Test conditions differ by circuit too. The form specifies warmer oil for steering and transmission measurements than for the blade hydraulic relief check. Its blade-lift timing entry separates low idle from full engine speed, and gives distinct standard and permissible limits.

Ask for the measured result and the conditions recorded. A limit printed on the form is not evidence that a particular used dozer achieved it. Stall and relief tests require the matching workshop procedure and suitable restraints; this comparison is for identifying the correct service reference.