Description

Bobcat 325, 328 1998 Service Manual

If you are tearing into a Bobcat 325 or 328 from 1998, you need the real factory documentation. I have been wrenching for 28 years, and I can tell you the difference between an OEM spec and aftermarket guesswork is the difference between a job done once and a comeback. This Bobcat 325, 328 1998 Service Manual is the actual Melroe-printed book, 463 pages of procedures that Bobcat service techs used on the shop floor. No condensed reprints, no third-party interpretations. You get the exact torque values, clearances, and diagnostic steps that the engineers put on paper.

Cooling System and Engine Overhaul

You can’t rebuild a diesel without cooling specs. The manual covers the radiator, fan guard, and coolant flow in the Cooling System chapter (page 1-1). It also gives you the cylinder head and block data under Cylinder Bore and Cylinder Head sections. Need the valve clearance adjustment procedure? That is under Valve – in the Engine chapter (7-1). Those specs are non-negotiable. I have seen guys skip the cold clearance on a Kawasaki engine and then wonder why the valve burns. Factory spec is factory spec. The manual also walks through piston ring gaps, connecting rod bolt torque (in ft-lbs), and the fuel injection pump timing. Every number comes from the same source that built the machine.

Hydraulic Cylinders: Torque and Rebuild Data

Hydraulics are where most field repairs go sideways. The manual has dedicated sections for every cylinder: Arm Cylinder, Boom Cylinder, Blade Cylinder, Bucket Cylinder, Boom Swing Cylinder. Each one shows the disassembly sequence, seal replacement, and the specific torque for the cylinder head gland nut. I have pulled apart too many cylinders where someone used a pipe wrench on the rod and trashed the chrome. The manual tells you which spanner wrench fits. It also covers the Auxiliary Selector Valve, Main Relief Valves, and Port Relief Valves – all with cross-port relief valve settings in psi. Do not attempt to adjust those without the specs on page 2-1. That page alone can save you from blowing a seal on a demo site.

Does the Manual Cover the Electrical System?

Yes. The Electrical System chapter (page 6-1) includes the wiring diagrams for both the 325 (S/N 514013001 & Above) and 328 (S/N 516611001 & Above). It shows the alternator, battery, glow plugs, fuel shut-off solenoid, and the instrument panel. For the later serial numbers, there is a specific section on Diodes. You need to identify which wire is which if you are chasing a no-crank condition. The manual also covers the buzzer and horn circuits. I have used these diagrams to isolate a bad ground on a joystick controller. Do not trust aftermarket wiring schematics – they often omit the cab electrical harness routing. This book gives you the factory color codes and connector pinouts. For later model years, check out the Bobcat 325 328 331 2006 Service Manual if you need updates for the 331, but for the 1998 machines this is the right one.

3 Reasons to Use Only OEM Documentation

First, aftermarket manuals sometimes round torque values to the nearest 5 ft-lb. That matters on a cylinder head bolt. Second, safety warnings are removed or condensed – the original manual has a full page on lifting and blocking the excavator, exhaust ventilation, and battery acid handling. Third, revisions: Bobcat issued service bulletins that affect torque specs on the swing motor drive carrier. The OEM manual includes those updates. The aftermarket stuff? Not a chance. If you are comparing this to a generic manual, do not. The original print is the only source you should use. For transmissions on different equipment, you might reference a Manual Transmission guide, but for Bobcat hydraulics, stick with this document.

Get the Right Valve Clearance Specs

Under the Engine Compression and Rocker Arm and Shaft sections, the manual lists the intake and exhaust valve clearance for both the 325 and 328. It also shows the valve seat angle and spring free length. I have seen technicians rely on a spec from the internet and end up with a clattering top end. The factory says .006 intake, .008 exhaust (cold) – and that is in the book. The fuel camshaft timing marks are also shown. One more thing: the manual includes the decimal and millimeter equivalents table on page 8-1. That is handy when you have a metric feeler gauge and need to confirm the thousandths conversion.

Every chapter in this manual was written for the tech who has the tools and the patience to do the job right. The TOC alone lists over 80 individual procedures from Accumulator (2-1) to Swing Motor Drive Carrier (4-1). You will find the cooling system, electrical troubleshooting, and hydraulic cylinder rebuilds all in one place. The manual also covers the service schedule, lubrication points, and daily maintenance checks from the Safety & Maintenance section. For a DIY mechanic or a shop owner, this is the blueprint you need to keep the excavator running. I have torqued more head bolts than most people have had hot meals, and I still reference the factory manual every time I work on a hydraulic system. The 1998 edition is specific to the serial numbers listed – do not try to use it on a 2007 machine. For that, get the Bobcat 325 328 2007 Service Manual or the Bobcat 325 328 2008 Service Manual. For a general understanding of power transfer, you can read about Manual Transmission principles, but on this excavator the hydraulics are your only concern.

Do not waste time with scanned PDFs from unknown sources. This is the original Melroe document, dealer copy, not for resale originally – but we are making it available for owners and techs who need the real data. The hydraulic reservoir capacity is in gallons, the engine oil viscosity is SAE 10W-30, and every bolt torque is in ft-lb. Get the manual, read the warnings, and do the job once. Access the Factory Manual.

Does this manual cover the Bobcat 331?

No. This manual covers only the 325 and 328 models from 1998 with the serial number ranges printed on the cover. For the 331, see the separate 2006 manual.

Are wiring diagrams included?

Yes.

What torque specs are listed for the cylinder head?

The manual lists all engine fastener torques in the Engine Specifications section (8-1). Cylinder head bolts are torqued in two stages with a final angle – the exact values are given in ft-lb and degrees. You must follow the sequence shown in the Cylinder Head chapter (7-1). I have had to re-torque heads that were done by guess. The spec is there. Use it.

Does the manual include hydraulic system troubleshooting?

Yes, there is a full page on Hydraulic System Troubleshooting (2-1) covering symptoms like slow travel, weak breakout force, and excessive drift. It also explains how to test cross-port relief valve pressures and check the case drain filter. This is the kind of diagnostic logic that saves you from swapping parts without fixing the root cause.