Save Money By Inspecting Your Motors Parts
In our previous installment of this engine teardown checklist we took care of most of the top-end of the engine and then took out the cam and examined the heads. If you missed that part you can find it here.
Now it’s time to dig into the rest of the engine.
Clik here to view.
Crank and Rod Removal – Now we can work on the bottom end of the motor. Remove the rod end caps and note the condition of the bearings. Shiny bearing surfaces mean the oil clearances were too tight on this motor.
Scratches or gouges mean that foreign material has gotten into the oil and you need to further investigate the source of the abnormal wear. Discoloration is another sign of overheating, either locally or the entire motor.
When you remove the crank journal bearing caps, again look for similar problems that were described being associated with the rod bearings. The crank bolts are the source of overheating odor. And again, note the force needed to break these bolts loose.
Clik here to view.
Pistons – We can remove the pistons and rods now. Note the color on the inside of the piston. It should be a brown color, but not too dark. A motor that ran hot shows up as burnt oil on the inside of the piston.
Also, if one or more of the pistons are very clean with no carbon buildup on the top, you might have a leaking head gasket and some water is finding its way into the combustion chamber and this steam cleans the piston. It is not normal.
Look at the skirts of the piston. Scratches or imbedded metal could show up. If re-using the pistons, you will need to bead blast the skirts to remove these tiny metal parts. Soda blasting is good for general cleaning of the carbon deposits on the piston, but won’t do a good job of removing the metal pieces imbedded in the piston skirt.
Observe the piston rings. The bottom compression ring should have a darker tone to it. A smooth and shiny ring is not a good sign and means it has lost lubrication. Wear on the piston ninety degrees around from the skirt means your crank is not aligned with the bore or you might have a bent rod.
Clik here to view.
Clik here to view.
Heads and Valve Train – Next comes the heads and valve parts. There is a lot to look at because much of the work a motor does occurs with these parts. Remove the valve springs and measure the free height as well as the installed pressure and open pressure.
If the spring has lost height, it must be replaced. The seat pressure must be within 10 to 15 pounds of new. If they are less than that, they must be replaced. Never install stiffer springs than you need.
Note any wear in the spring caps or valve guides. A wet oily spot near where the valve enters the intake or exhaust runners means the valve guides are worn. Check your rocker arms for excess play and note where the rocker is contacting the valve stem. You might need to rethink your valve train geometry in the future.
Check the push rod tips for wear or lack of lubrication. Sometimes the packing grease that comes with new rods can enter the rod and harden blocking the flow of lubricant causing damage. Completely clean and inspect your rods before installation.
Clik here to view.
Fuel Pump – To complete the disassembly of the block, we now remove the mechanical fuel pump. Check the pump shaft for play and condition. Any other accessories mounted to the motor should be checked and re-built if necessary. Check your headers for leaks and sand blast and repaint. Carbon buildup in the headers can cause a loss of exhaust gas flow and performance.
Engine Block – Now that we have a bare block, we can look at the cylinders and overall condition of the entire block. We need to check the bore size all of the way up and down the stroke area where the piston rides along the bore. What we are looking for, but don’t want to see, is taper, or difference in the diameter of the bore, usually with the larger dimension being lower in the bore.
Also check for concentricity of the bore. As you measure, move 120 degrees around the bore for three measurements so that you can see if the bore is truly round. The bore might be smooth, but should not have any vertical lines cut into it.
Now is a good time to remove those freeze plugs. Your engine builder, or you, will install new ones as a part of the re-build.
Clik here to view.
Conclusion – So now we have disassembled and inspected the entire motor. We can feel comfortable that either the motor was properly assembled the last time and maintained throughout the season, reducing the re-build costs, or it wasn’t. Either way, we know what we need to do to put it back together and freshen it for the following season.
Take this opportunity to plan out your engine maintenance schedule for the coming season. If your valve springs all came up short, make sure to replace the springs at mid-season so that your power level will be maintained through that late season push for points.
If the motor shows signs of overheating, re-evaluate your cooling system so that this problem does not repeat itself. Having a reliable and powerful engine makes any racing effort easier and provides more time to work on your setup.
The post Save Money by Inspecting Your Motor Parts (Bottom End) appeared first on Hot Rod Network.