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The old-type Hitachi fan motor is the one that comes back as a warranty argument most often, for a reason that has nothing to do with the part. It is the motor that sits behind the radiator on machines that have already had one heat event, so by the time it fails, the circuit is usually carrying the debris from whatever caused the first failure. Replacing the motor without dealing with the circuit is how a yard ends up with two failed motors and a bad review.
Identifying this unit on the bench
Four features separate it from the newer YA00005829 type and from the Parker-built original:
- Housing. A dark grey cast body with a distinctly conical upper section, rather than the flat-topped rectangular Parker casting or the compact eared KYB body.
- Mounting. Four-bolt square flange, with the work ports on a side block covered by a silver plate.
- Shaft. Keyed, retained by a hex nut. Some units in this family are supplied with a threaded shaft end for a different fan hub, which is one more reason to send a photograph of your old part.
- Cast marks. Our units carry XJF and NSC batch castings plus the cross number 93467079E, the number that ties this motor family to Deere-Hitachi parts data as well as to Hitachi’s own 4634936 and 4634947.
If the plate on your machine reads Parker M5BF 045, the physical original is on our 4634936 Parker fan motor page, and this listing is the replacement grade for that position. If your machine carries the KYB MSF unit, the correct replacement is our YA00005829 replacement fan motor.
Fitment
Listed for Hitachi ZX450-3, ZX470-3, ZX850-3 and ZX870-3, and cross-referenced in trade data against ZX470LC-5B, ZX500LC-3, ZX520LCH-3, ZX670LC-5B, ZX870-5B and ZX870-5G, plus Deere-Hitachi forestry machines of the same families. That is a wide list and it should be treated as a starting point. Hitachi changed the fan drive assembly between the -3, -5 and -6 generations, and the number stamped on your housing outranks any catalogue.
What actually goes wrong, and what to do about it
Internal wear from contamination. The slow failure. Clearances open, volumetric efficiency falls, the fan stops reaching full speed at high idle, and coolant and oil temperatures climb together during loading cycles. There is no single test that reveals it; the symptom is a fan that is merely disappointing. Measure flow at the motor ports against the machine’s specification rather than judging by eye.
Shaft seal leakage from drain back-pressure. The fast failure, and almost always self-inflicted. A kinked, blocked or badly routed case drain line puts pressure on the seal lip. The published ceiling for axial piston units of this size band is 0.1 MPa in normal running and 0.4 MPa at peak. After a radiator or fan guard has been removed, check that line specifically.
Heat from the rest of the circuit. Oil held above about 90 degrees centigrade thins the film and the motor wears faster every hour. If the oil temperature is high, the cause is usually elsewhere: internal leakage in the main pumps, a regulator stuck at cut-off, or a plugged oil cooler. Our check valve diagnosis covers the case where every wear part has been replaced and the machine still runs hot.
Hydrostatic lock and water. The sudden failure. Water in the oil, or a machine standing with a leaking drain line, locks the casing. Check the oil condition before you condemn anything.
Prevention checklist for the fitting
- Sample the oil and read it before the new motor goes on. Grit means a flush; shiny particles mean the circuit needs cleaning and the filter needs changing.
- Fit a 10 micron return filter element and confirm the suction strainer is clear. Target NAS 1638 class 9, which is ISO 4406 18/15.
- Fill the motor casing with clean oil before cranking, and bleed with the fan restrained.
- Confirm rotation direction and the reverse function before the guard is refitted. Work through the fan motor diagnosis guide if the machine came in with an unexplained heat fault.
- Log coolant and hydraulic oil temperatures at low and high idle after the job, so the next 500 hours have a baseline.
Terms
Minimum order one piece, around 1,000 units a month available for fleet orders. Each motor is bench-checked, photographed against your order and packed in a wooden case or to your specification. Delivery 5 to 8 working days from payment subject to stock, by sea, air or express courier. Payment by L/C, T/T, PayPal or Western Union. New aftermarket units carry a three to six month warranty as stated on the proforma invoice; genuine and used stock is sold without warranty. The full range is under hi̇droli̇k fan motoru ve Hitachi parts.
