Perkins 704-26 Service Manual – Factory Repair Specs for Model UB

Description

You’ve got a Perkins 704-26 that won’t start, or it’s knocking, and you’re staring at a pile of parts wondering if you torqued that Perkins 704-26 Service Manual right. I’ve been there. The difference between a rebuild that lasts and one that leaks is a factory manual you can trust. This is that manual. Perkins printed 77 pages of instructions for the 704-26 UB engine—2.6 litre, four-cylinder, liquid-cooled, indirect injection diesel. Every page comes from the original factory file, not some scanned reprint.

Cylinder Head Assembly: Valve Clearance and Torque

This section walks through valve cover removal, the breather system cleaning, and rocker assembly disassembly. You’ll find the steps to adjust valve clearances—not a generic range, but the exact clearance for inlet and exhaust valves. The procedure tells you how to find piston TDC so you set the rockers on the base circle. If you need to replace a valve spring, the manual shows the order: remove the rocker assembly, compress the spring, and install the new one. That kind of step-by-step keeps you from bending a pushrod.

Does This Manual Cover the Fuel System?

Yes. The Fuel System chapter covers fuel filter replacement, injector removal and inspection, fuel pump disassembly, and the water separator. It also includes the fuel injection pump removal and installation, plus a procedure to remove air from the fuel system. The governor weight assembly and engine speed control assembly are in there too. If you’re chasing a low-power complaint, the manual explains how to record the maximum fuel position of the fuel rack. That keeps you from guessing on a pump that’s out of adjustment.

Engine Timing: Set TDC Without Guessing

The Engine Timing section gives you a general description and then tells you exactly how to set the timing of number one piston to top-dead-centre. It also covers checking valve timing and fuel pump timing. Timing marks on the crankshaft pulley and the injection pump gear have to line up. If you skip that step, you’ll be pulling the timing case back off. This chapter also shows the idler gear removal and installation, and the camshaft assembly for both fuel injection pump and valves.

3 Reasons to Rely on OEM Specs

First, the torque values. The manual lists cylinder head bolt torque, main bearing cap torque, connecting rod torque—all from Perkins engineering, not an aftermarket rebuild book. Second, the inspection limits: cylinder bore wear, valve guide clearance, piston ring gap. Those numbers tell you when to replace, not just when to check. Third, the safety notes. The General Safety Rules section covers handling Viton seals—if you burn one, you need to use neoprene gloves and calcium hydroxide solution. A third-party manual might skip that.

Lubrication System: Oil Pump and Relief Valve

This chapter describes the oil filter replacement, oil sump removal and installation, oil pump removal and inspection, and the relief valve. If your engine has low oil pressure, the manual shows you how to disassemble and inspect the relief valve. The oil pump inspection includes checking the gear clearance. Replacement procedures are given for the rear oil seal and wear sleeve. You get the axial movement check for the crankshaft thrust washers too—that’s how you verify main bearing wear before a rebuild.

Every procedure comes from the original Perkins documentation, not a third-party rewrite. The 77 pages are organized with bookmarks so you can jump to the cylinder block inspection, checking cylinder bore, or the engine specifications. You want the valve spring free length? It’s in the Engine Specifications chapter. Need the alternator or starter motor removal steps? That’s in the Electrical Equipment section. This is the same manual a dealer technician would use.

Related manuals for this engine family: Perkins 704-26 UB Service Manual, Perkins 704-26 2003 Service Manual – Factory OEM Diesel Engine, and Perkins 404C-22 400 2004 Service Manual – OEM Factory Specs. If you’re working on a vehicle that has a manual transmission, Manual Transmission repair procedures are a separate topic, but this engine manual covers the power unit itself.

What engine models does this manual cover?

The Perkins 704-26 UB, specifically the 2.6L four-cylinder indirect injection diesel.

Does the manual include step-by-step instructions for valve adjustment?

Yes. The Cylinder Head Assembly section covers valve cover removal, rocker assembly disassembly, and the procedure to adjust valve clearances. It also tells you how to find piston TDC. The manual includes specifications for inlet and exhaust valve clearances from the Engine Specifications chapter. That means you can set them cold or hot according to factory specs, not some generic number. Plus there are safety warnings about Viton seals and proper handling.

If you want to rebuild this Perkins 704-26 without hunting for torque values on forums or trusting a generic engine book, get the factory document. Access the Factory Manual now and keep it on your tablet or print it for the bench. One job with this manual will pay for itself the first time you don’t have to re-torque a head gasket.