Toyota Pick-ups/Land Cruiser/4Runner 1970-1988

Engine Overhaul

Imprimir

Most engine overhaul procedures are fairly standard. In addition to specific parts replacement procedures and complete specifications for your individual engine, this section also is a guide to accept rebuilding procedures. Examples of standard rebuilding practice are shown and should be used along with specific details concerning your particular engine.

Competent and accurate machine shop services will ensure maximum performance, reliability and engine life. Procedures marked with the symbol shown above should be performed by a competent machine shop, and are provided so that you will be familiar with the procedures necessary to a successful overhaul.

In most instances it is more profitable for the do-it-yourself mechanic to remove, clean and inspect the component, buy the necessary parts and deliver these to a shop for actual machine work.

On the other hand, much of the rebuilding work (crankshaft, block, bearings, piston rods, and other components) is well within the scope of the do-it-yourself mechanic.

TOOLS



The tools required for an engine overhaul or parts replacement will depend on the depth of your involvement. With a few exceptions, they will be the tools found in a mechanic's tool kit (see General Information & Maintenance ). More in-depth work will require any or all of the following:



a dial indicator (reading in thousandths) mounted on a universal base
 
micrometers and telescope gauges
 
jaw and screw type pullers
 
scraper
 
valve spring compressor
 
ring groove cleaner
 
piston ring expander and compressor
 
ridge reamer
 
cylinder hone or glaze breaker
 
Plastigage®
 
engine stand
 

Use of most of these tools is illustrated in this section. Many can be rented for a one-time use from a local parts jobber or tool supply house specializing in automotive work.

Occasionally, the use of special tools is called for. See the information on Special Tools and Safety Notice in the front of this guide before substituting another tool.

INSPECTION TECHNIQUES



Procedures and specifications are given in this section for inspecting, cleaning and assessing the wear limits of most major components. Other procedures such as Magnaflux® and Zyglo® can be used to locate material flaws and stress cracks. Magnaflux® is a magnetic process applicable only to ferrous materials. The Zyglo® process coats the material with a fluorescent dye penetrant and can be used on any material Check for suspected surface cracks can be more readily made using spot check dye. The dye is sprayed onto the suspected area, wiped off and the area sprayed with a developer. Cracks will show up brightly.

OVERHAUL TIPS



Aluminum has become extremely popular for use in engines, due to its low weight. Observe the following precautions when handling aluminum parts:



Never hot tank aluminum parts (the caustic hot-tank solution will eat the aluminum.
 
Remove all aluminum parts (identification tag, etc.) from engine parts prior to the tanking.
 
Always coat threads lightly with engine oil or antiseize compounds before installation, to prevent seizure.
 
Never overtorque bolts or spark plugs especially in aluminum threads.
 

Stripped threads in any component can be repaired using any of several commercial repair kits (Heli-Coil®, Microdot®, Keenserts®, etc.).

When assembling the engine, any parts that will be frictional contact must be prelubed to provide lubrication at initial start up. Any product specifically formulated for this purpose can be used, but engine oil is not recommended as a prelube.

When semipermanent (locked, but removable) installation of bolts or nuts is desired, threads should be cleaned and coated with Loctite® or other similar, commercial nonhardening sealant.

REPAIRING DAMAGED THREADS



See Figures 1, 2, 3, 4 and 5



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Fig. Fig. 1: Damaged bolt holes can be repaired with thread repair inserts



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Fig. Fig. 2: Standard thread repair insert (left) and spark plug thread insert (right)



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Fig. Fig. 3: Drill out the damaged threads with specified drill--drill completely through the hole or to the bottom of a blind hole



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Fig. Fig. 4: With the tap supplied, tap the hole to receive the thread insert--keep the tap well oiled and back it out frequently to avoid clogging the threads



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