Engine Blocks And Inspection For Rebuilding
Written by Bill Maxim   
Saturday, 03 July 2010 07:12
If performing an engine rebuild for an ordinary vehicle, or commercial application, some automotive enthusiasts may find the need to replace their engine block. Because used engine blocks may be expensive, and can have hidden flaws, there are some general considerations a person can take before buying a different block that can save a serious amount of money down the road.
by BillMaxim


Whether performing an engine rebuild for a daily driver, or high performance application, some engine builders may have the need to replace their engine block. Since used engine blocks can be costly, and usually have hidden defects, there are some basic precautions one can take before purchasing a different block that can save a significant amount of money down the road.

How the used engine block was stored is extremely important in deciding whether it should even be considered for purchase. Engine blocks that have been kept outside probably have been exposed to rain water and cold temperatures. When combined, water can freeze and expand which may crack the cylinder walls or casting. Most cracks are hard to find and often are costly to fix. Rust and pitting may also occur inside the cylinders and be so damaging that even boring to the maximum oversize would not take out enough material to adequately clean up the cylinder walls. In situations of extraordinary pitting, each cylinder would need to be sleeved.

It is possible that a used engine block has been machined. Because of this, it is important to determine how much machining may be required. With this current dimensions, the automotive enthusiast can do some research of their own to make sure pistons and rings are available in the oversize that the cylinder block will clean at. For difficult to find cylinder blocks, especially in the case of restoration builds, an extremely limited number of pistons and rings may be available.

When purchasing a pre-owned block, the engine builder must also pay close attention to the main caps. Main caps that have a cross hatch pattern in them more then likely have been machined outside of the factory. Assuming the align bore is within tolerance, it is likely that an undersized timing chain set might need to be purchased to allow for adequate chain tension and valvetrain timing.

Buying a cylinder block with the matching main caps is extremely important. The cost of align boring and honing will easily exceed a couple hundred dollars and increase the final expense of rebuilding the engine.

Thoroughly inspecting a used cylinder block is best conducted when it is has been cleaned. With a clean block, many visible defects or damage can be easily seen. Also, important tolerances may be verified much easier and accurately with a clean block. When purchasing a block for an engine rebuild, a through inspection can possibly save the engine rebuilder hundreds and even thousands of dollars.

About the Author:

Bill Maxim is an ASE Certified engine machinist that has performed a variety of engine block machining processes needed to remanufacture engines. Bill has over 10 years of experience as a Certified automotive machinist.