A403154 T/M Oil Pump Unit for Doosan D15/18S5 Forklift

Overview

The A403154 T/M Oil Pump Unit is the transmission oil pump for a range of Doosan diesel forklifts, including the D15/18S5 and D20/25/30/33S5 series. The pump sits at the heart of the transmission’s hydraulic circuit: it draws fluid from the sump and delivers it under pressure to lubricate gears, bearings, and clutch packs while supplying the force needed for smooth forward and reverse engagement. When this pump wears, operators typically notice delayed shifting, whining or growling noises, low line pressure, or sluggish travel response. Left unaddressed, poor oil flow accelerates wear across the entire transmission. Fitting the correct replacement pump restores pressure, protects internal components, and keeps the truck working.

Compatibility

The A403154 oil pump unit is specified for the following Doosan forklift families:

• D15/18S5 series — a fitment frequently searched as “A403154 for D15/18S5”
• D20/25/30/33S5 series — diesel counterbalance trucks in the S5 range
• D20SC-5 (chassis code SB1089) and D20SC5 (chassis code SB1127)
• D35C5 (chassis code SB1092, fitted with the Cummins B3.3 engine)

Because closely related models can use different pumps, always confirm the part number on your machine’s identification plate or in the Doosan parts manual before ordering. If you are unsure, our team can help verify fitment against your model and serial number.

Quality and Reliability

Transmission pumps run at high pressure with tight internal clearances, so precision matters. This T/M Oil Pump Unit is built to Doosan specifications for flow rate, mounting geometry, and pressure output, allowing it to drop into place without modification. A dependable pump maintains consistent line pressure, which protects the torque converter, clutch packs, and gear train from premature wear. Replacing a worn pump is a small expense compared with a full transmission rebuild, making timely replacement one of the most cost-effective repairs on a hard-working forklift.

Installation and Maintenance Tips

• Verify the fault first: check fluid level and condition, the suction strainer, and intake lines before condemning the pump.
• During installation, replace the transmission filter and refill with the transmission fluid specified by Doosan.
• Clean the mounting face and fit new gaskets or seals to prevent air ingestion and pressure loss.
• Follow the service manual for priming and check line pressure after startup.
• Inspect drained fluid for metal particles; if present, locate the source before returning the truck to service.

Why Order from Us

for liftpartssearch.com specializes in forklift replacement parts, and the A403154 T/M Oil Pump Unit for Doosan applications is part of a deep catalog covering the S5 truck families. We help you match part numbers to machines, answer technical questions before you buy, and supply the Doosan components your service team needs. Order with confidence and get your forklift back to work.