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

Cylinder Block

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See Figure 1

Most inspection and service work on the cylinder block should be handled by a machinist or professional engine rebuilding shop. Included in this work are bearing alignment checks, line boring, deck resurfacing, hot-tanking and cylinder honing or boring. A block that has been checked and properly serviced will last much longer than one which has not had the proper attention when the opportunity was there for it.

Cylinder de-glazing (honing) can, however, be performed by the owner/mechanic who is careful and takes his or her time. The cylinder bores become glazed during normal operation as the rings continually ride up and down against them. This shiny glaze must be removed in order for a new set of piston rings to be able to properly seat themselves.

Cylinder hones are available at most auto tool stores and parts jobbers. With the piston and rod assemblies removed from the block, cover the crankshaft completely with a rag or cover to keep grit from the hone and cylinder material off of it. Chuck a hone into a variable speed power drill (preferable here to a constant speed drill), and insert it into the cylinder.

Make sure the drill and hone are kept square to the cylinder bore throughout the entire honing operation.

Start the hone and move it up and down in the cylinder at a rate which will produce approximately a 60° cross-hatch pattern. DO NOT extend the hone below the cylinder bore! After developing the pattern, remove the hone and recheck piston fit. Wash the cylinders with a detergent and water solution to remove the hone and cylinder grit. Wipe the bores out several times with a clean rag soaked in clean engine oil. Remove the cover from the crankshaft, and check closely to see that no grit has found its way onto the crankshaft.



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Fig. Fig. 1: Cylinders should be honed to look like this

 
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