Toyota Engine >> CYLINDER BORING CAUTION

Toyota Engine >> CYLINDER BORING CAUTION

Cylinder Boring Caution For
1986-99 Toyota 1.5, 2.0 & 2.2L 5E, 3S & 5S Engines

The AERA Technical Committee offers the following information regarding a cylinder boring caution for 1986-99 Toyota 1.5, 2.0 & 2.2L 5E, 3S & 5S engines. AERA originally published information regarding only the 1.5L engine. This publication includes additional engines with a similar concern. This caution has been reported on engines that have been bored to a .040 (1.000 mm) oversize diameter.

Apparently, depending on the amount of overbore the cylinder wall thickness may become insufficient to support compression. Reports of compression in the cooling system have resulted when the bore diameter has been increased by as little as .040 (1.000 mm) oversize.

These blocks have three angular coolant passages between the cylinders as shown below in Figure 1. The passages are drilled at approximately a 45° angle from the engine right side to the engine left side. These passages allow coolant flow between the cylinders and connect the right to left side water jackets.

The shadow of the drilled passage can be seen in Figure 2 as a dark shadow on a failed block that had been bored and honed .040 and placed back in service. Combustion pressure within the cylinder after start-up created the through hole into the water jacket, resulting in combustion in the cooling system. Engine overheating will result when this condition exists. To repair this condition, AERA members report installing cylinder sleeves and then boring back to a standard bore diameter for all cylinders.

The AERA Technical Committe

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