1991 Chevrolet V1500 Suburban Service & Repair Manual Software

Contents Chapter 1 Introduction How to use this repair manual 1-1 What is an overhaul? 1-1 Engine identification 1-2 Parts interchangeability 1-6 Buying parts 1-11 Chapter 2 Tools and equipment A place to work 2-1 Tools and equipment 2-3 Fasteners 2-37 Component disassembly 2-41 Gasket sealing surfaces 2-41 Hose removal tips 2-42 Automotive chemicals and lubricants 2-42 Safety first! 2-43 Chapter 3 Diagnosing engine problems General information 3-1 Reading symptoms 3-1 Measuring oil consumption 3-2 Diagnostic checks 3-2 Is the engine worth rebuilding? 3-11 Chapter 4 Preparing for an overhaul Preparing to remove the engine 4-1 Removing the engine 4-2 Removing the external engine components 4-11 Chapter 5 Overhauling the cylinder heads Removing the cylinder heads 5-1 Rebuilding the cylinder heads 5-3 Inspecting the valve springs 5-11 Assembling the heads 5-13 Installing the heads 5-14 Installing the valve train 5-16

Chapter 6 Overhauling the engine block Disassembly 6-1 Cleaning and inspection 6-5 Machine shop procedures 6-17 Choosing piston rings and honing the cylinders 6-19 Reassembly 6-21 Chapter 7 Reassembling and installing the engine Introduction 7-1 Replacing the front transmission seal 7-1 Assembling the engine 7-3 \r\staU\ngthe engine 7-14 Starting the engine 7-15 Breaking in the engine 7-16 Chapter 8 Related repairs Carburetor overhaul 8-1 Distributor overhaul 8-3 Fuel pump overhaul 8-5 Starter overhaul 8-5 Generator overhaul 8-10 Alternator overhaul 8-10 Chapter 9 Improving performance and economy Introduction 9-1 Camshaft selection 9-3 Exhaust modifications 9-8 Ignition systems 9-11 Intake manifolds 9-12 Carburetors 9-14 Making it all work together 9-18 Engine swaps 9-18 Glossary GL-1 Appendix A Booster battery (jump) starting AP-1 B Conversion factors AP-2 C Electrical glossary AP-3 D Understanding wiring diagrams AP-12 Index iND-1

Introduction How to use this repair manual The manual is divided into Chapters. Each Chapter is sub-divided into Sections, some of which consist of con- secutively numbered Paragraphs (usually referred to as "Steps", since they're normally part of a procedure). If the material is basically informative in nature, rather than a step-by-step procedure, the Paragraphs aren't numbered. The first three Chapters contain material on preparing for an overhaul. The remaining Chapters cover the specifics of the overhaul procedure. Comprehensive Chapters covering tool selection and usage, safety and general shop practices have been included. The term "see illustration" (in parentheses), is used in the text to indicate that a photo or drawing has been included to make the information easier to understand (the old cliche "a picture is worth a thousand words" is especially true when it comes to how-to procedures). Also, every attempt is made to position illustrations directly opposite the corresponding text to minimize confusion. The two types of illustrations used (photographs and line drawings) are referenced by a number preceding the caption. Illustra- tion numbers denote Chapter and numerical sequence within the Chapter (i.e., 3.4 means Chapter 3, illustration number four in order). The terms "Note", "Caution", and "Warning" are used throughout the text with a specific purpose in mind - to attract the reader's attention. A "Note" simply provides information required to properly complete a procedure or information which will make the procedure easier to understand. A "Caution" outlines a special procedure or special steps which must be taken when completing the procedure where the Caution is found. Failure to pay attention to a Caution can result in damage to the component being repaired or the tools being used. A "Warning" is included where personal injury can result if the instructions aren't fol- lowed exactly as described. Even though extreme care has been taken during the preparation of this manual, neither the publisher nor the author can accept responsibility for any errors in, or omis- sions from, the information given. What is an overhaul? An engine overhaul involves restoring the internal parts to the specifications of a new engine. During an overhaul, the piston rings are replaced and the cylinder walls are reconditioned (rebored and/or honed). If a rebore is done, new pistons are required. The main bearings, connecting rod bearings and camshaft bearings are generally replaced with new ones and, if necessary, the crankshaft may be reground to restore the journals. Generally, the valves are serviced as well, since they're usually in less-than-perfect condition at this point. While the engine is being overhauled, other components, such as the distributor, starter and alternator, can be rebuilt as well. The end result should be like a new engine that will give many thousands of trouble-free miles. Note: Critical cooling sys- tem components such as the hoses, drivebelts, thermostat 1-1

Haynes Chevrolet engine overhaul manual 1.1 Typical Chevrolet code number locations and water pump MUST be replaced with new parts when an engine is overhauled. The radiator should be checked care- fully to ensure that it isn't clogged or leaking; if in doubt, replace it with a new one. Also, always install a new oil pump when overhauling the engine - we recommend against rebuilt pumps. It's not always easy to determine when, or if, an engine should be completely overhauled, as a number of factors must be considered. High mileage is not necessarily an indication that an overhaul is needed, while low mileage doesn't preclude the need for an overhaul. Frequency of servicing is probably the most important consideration. An engine that's had regular and frequent oil and filter changes, as well as other required maintenance, will most likely give many thousands of miles of reliable service. Conversely, a neglected engine may require an overhaul very early in its life. Excessive oil consumption is an indication that piston rings, valve seals and/or valve guides are in need of attention. Make sure that oil leaks aren't responsible before deciding that the rings and/or guides are bad. Perform a compression check (see Chapter 3) and have a leak-down test performed by an experienced tune-up mechanic to determine the extent of the work required. If the engine is making obvious knocking or rumbling noises, the connecting rod and/or main bearings may be at fault. Check the oil pressure with a gauge installed in place of the oil pressure sending unit or switch (see Chapter 3) and compare it to the specifications for the particular engine (see the Haynes Automotive Repair Manual for your vehicle). If it's extremely low (generally, less than 10 psi at idle), the bearings and/or oil pump are probably worn out. Loss of power, rough running, excessive valvu train noise and high fuel consumption rates may also point to the need for an overhaul, especially if they're all present at the same time. If a complete tune-up doesn't remedy the situa- tion, major mechanical work is the only solution. Before beginning the engine overhaul, read through this entire manual to familiarize yourself with the scope and requirements of the job. Overhauling an engine isn't partic- 1.2 Check for a casting number at the rear of the block (arrow) ularly difficult if you have the correct equipment; however, it is time consuming. Plan on the vehicle being tied up for a minimum of two weeks, especially if parts must be taken to an automotive machine shop for repair or reconditioning. Check on availability of parts and make sure that any necessary special tools and equipment are obtained in advance. Most work can be done with typical hand tools, although a number of precision measuring tools are required for inspecting parts to determine if they must be replaced. Often an automotive machine shop will handle the inspection of parts and offer advice concerning reconditioning and replacement. Engine identification Identifying just which engine you have is critical because Chevrolet engines which are very similar in appearance can be quite different in important details. Prior to 1972 on passenger cars and 1973 on light trucks, the Vehicle Identification Number (VIM) only indicates whether the vehicle originally came with a six-cylinder or a V8. Some of these engines can be identified by the decals on the air cleaner or the valve covers. If these markings are missing or you suspect they are incorrect, check for numbers on the engine. Record the VIN number (see illustration) and also the casting number on the rear of the engine block between the distributor and bellhousing (see illustration). Also note the shape of the casting marks on the ends of the cylinder heads (later models don't have these). Using this information, check with your local dealer parts depart- ment or salvage yard for assistance in identification. On 1972 and newer passenger cars and 1973 and newer light trucks, the first step of engine identification is to look at the VIN, because the VIN includes a code letter that indicates which engine the vehicle is equipped with. The VIN plate is located at the left front corner, just inside the windshield on passenger cars or on the door jamb of trucks and vans (see illustrations). 1-2

Introduction CHEVROLET Passenger Cars Example (1972 through 1980 models) Model Year Codes 2 = 1972 3 = 1973 4 = 1974 5 = 1975 6 = 1976 7 = 1977 8 = 1978 9 = 1979 0 = 1980 B =1981 C = 1982 D = 1983 E = 1984 F =1985 G = 1986 H = 1987 J =1988 K = 1989 L =1990 X X XX L S^X XXXXXX Engine Model year code code Example (1981 through 1990 models): X XXX XXX L X BX XXXXXX Engine Model year code code 1972 Code F H J K L R S U V \N C.I. 307 350 350 350 350 400 402 402 454 454 H.P. (130 HP) (165 HP) (175 HP) (200 HP) (255 HP) (170 HP) (210 HP) (240 HP) (230 HP) (270 HP) 1973 F H J K R T X Y Z 307 350 350 350 400 350 454 454 454 (115HP) (145 HP) (190 HP) (175 HP) (150 HP) (245 HP) (215 HP) (245 HP) (275 HP) 1974 Code H J K L R T U Y Z C.I. 350 350 350 350 400 350 400 454 454 H.P. (145 HP) (195 HP) (185 HP) (160 HP) (150 HP) (245 HP) (180 HP) (235 HP) (270 HP) 1975 G H J L T U Y 262 350 350 350 350 400 454 (145 HP) (165 HP) (155 HP) (205 HP) 1976 Code G L Q C.I. 262 350 305 H.P. (165 HP) 1976 (con't) Code S U V X C.I. 454 400 350 350 H.P. (145 HP) (210 HP) 1977 L U X 350 305 350 (170 HP) (210 HP) 1978 H L 350 350 (220 HP) (170 HP) 1979 G H J L 4 8 305 305 267 350 350 350 (2 barrel) (4 barrel) 1.3 Passenger car V8 engine codes 1-3

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1991 Chevrolet V1500 Suburban Service & Repair Manual Software

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