Removing the Crankshaft
Removing the crankshaft will require engine removal and disassembly. before removing the crankshaft, it is a good practice to measure endplay and clearance. use a feeler gauge to measure clearance and a dial indicator to determine the amount of endplay.
The crankshaft is usually removed after removing the main bearing caps. Reverse the torque sequence of the main bearing cap bolts to prevent warpage.
When the crankshaft is removed, do not store it by laying it down; it should be supported at the ends and in the middle. If a support fixture is not available, stand the crankshaft on end after securing it so it cannot fall.
- Remove the main cap bolts.
- Use a dial indicator torque wrench to see how tight they were.
- Remove the main caps. They fit tightly in the block.
Remove the main bearing caps, then lift the crankshaft from the block. Reprinted with the permission of the Ford Motor Company.
Main caps are not interchangeable, and must be returned to their original positions.
- Normally, bearings are replaced. If bearings are reused, they must be returned to their original positions, as they have been wear-mated to the crank journals.
- Carefully lift out the crankshaft. It has a flywheel or flexplate bolted to it.
A flywheel and flexplate. Courtesy of Ford Motor Corporation.
- The crank should be rested on end (vertically) during storage or hung in a rack to prevent warping. Leave the flywheel or flexplate bolted to the crank to help hold it upright during storage.
- Check to see if there is a pilot bearing or bushing in the rear of a standard transmission crankshaft. it can be removed with a slide hammer puller.
Most crankshafts used with manual transmissions have a piot bushing or bearing located near the rear flange.
- Check the condition of the crankshaft surface where the rear main seal rides.
- Inspect the bearing surfaces of the crankshaft for wear. Measure the main and connecting rod journals with a micrometer and compare them to manufacturer's specifications.
- Inspect the thrust bearing surfaces. These surfaces control fore and aft movement of the crankshaft. Wear, which is unusual, is usually greatest on the rear side.
Neoprene rear seal installation. Courtesy of Ford Motor Company.
- Inspect the front upper bearing to see if there is any sign of wear resulting from belts that were too tight.
- Label the backs of the main bearings with a felt marker with their positions. The number one upper main bearing is marked 1U, the number one lower is marked 1L, and so on. Place them in a line to inspect them for wear.
Preparing the Crankshaft for Installation
Check the following items to prepare the crankshaft for installation:
- Remove the old crankshaft sprocket.
- If the new one is pressed-fit, install it before installing the crank in the block.
Replace the crankshaft sprocket before installing the crankshaft in the block. Courtesy of General Motors Corporation, Service Technology Group.
- This will prevent damage to the thrust main bearing surface when the sprocket is pounded on.
- Make certain that the woodruff key is perfectly flat in its groove in the crank.
- An improperly installed woodruff key can cause a cracked sprocket.
Careless installation of the crank sprocket can ruin it. Courtesy of Federal-Mogul Corporation.
- The sprocket can be heated for easier installation if the crank is already in the block.
- Some crank sprockets slide easily into place.
- Install the sprocket with the timing mark facing outward.
- The inside edge of the sprocket has a chamfer that corresponds to the fillet on the crank; if the sprocket is backward it cannot be installed all the way.
The inside edge of a crankshaft sprocket is beveled to clear the fillet on the crankshaft.
- Be sure that all oil passages in the crank are clean.
Make sure that all crankshaft oil holes are clean. Courtesy of Federal-Mogul Corporation.
- Run a small bore brush through all of the oil passages in the crankshaft and wipe the journals with a clean shop cloth.
- Be sure that the surface the rear seal rides on is clean. If it is not, clean it with very fine emery or crocus cloth.
Clean the crankshaft rear sealing surface with crocus or emery cloth.
- Prepare the block by cleaning the oil galleries again and wiping the bearing surfaces of the block and caps.
- Rotate the engine block so the crankcase is facing up.
- If the vehicle is equipped with a manual transmission, the crankshaft may be fitted with a pilot bushing or bearing.
- It is a good practice to replace this bushing because it maintains the centerline alignment between the crankshaft and transmission input shaft.
- Be sure the bearings are the correct size for the crankshaft and bores.
- Use the service manual to determine the correct bearings to be used.
Installing the Crankshaft
The crankshaft is heavy and awkward to handle. Improper handling can result in damage to the crankshaft, block, or bearings. To make installation of the crankshaft easier and safer, lift the crankshaft by the harmonic balancer journal and by bolts threaded into the rear flange. Keep the crankshaft parallel as it is lowered into the bearings. If it is installed properly, the crankshaft will seat squarely and be supported by the bearings. The crankshaft should rotate freely with no binding or restrictions. Correct any problems before continuing.
- Clean the main bearing bores to prevent oil clearance and heat transfer problems.
Clean the main bearing bore. Courtesy of Federal-Mogul Corporation.
- If dirt is left on the bearing bore, the bearing can be forced against the crankshaft.
Results of careless cleaning. Courtesy of AE Clevite Engine Parts.
Be especially careful to clean the recesses where the bearing lock tab will fit. Failure to clean this area thoroughly is often the cause of a tight crankshaft.
- Install the upper main bearings by pushing them into the main bearing bores.
Snap the bearing into place. Courtesy of Federal-Mogul Corporation.
- Be sure that the lubricating holes in the bearings line up properly with the corresponding holes in the block.
Installing the main bearings in the wrong positions can block the passage of oil to the journals. Courtesy of AD Clevite Engine Parts.
- Do not touch the bearing surface with your hands.
- Lubricate the bearings only on the surface that is toward the crankshaft.
Do not oil the bearing backs. They are not a bearing surface.
- Check the bearing oil clearance with a plastigage.
Proper lubrication and cooling of the bearing depend on correct crankshaft oil clearances. Scored bearings, worn crankshaft, excessive cylinder wear, stuck piston rings, and worn pistons can result from too small an oil clearance. If the oil clearance is too great, the crankshaft might pound up and down, overheat, and weld itself to the insert bearings.
- Install the crank and check the clearance again.
- The crankshaft is heavy and awkward to handle.
- Improper handling can result in damage to the crankshaft, block, or bearings.
- To make installation of the crankshaft easier and safer, lift the crankshaft by the harmonic balancer journal and by bolts threaded into the rear flange.
- Keep the crankshaft parallel as it is lowered into the bearings.
- If it is installed properly, the crankshaft will seat squarely and be supported by the bearings.
- The crankshaft should rotate freely with no binding or restrictions.
- Correct any problems before continuing.
- If the crank and/or the bearings are being reused, it is advisable to check each bearing's clearance.
Often, during an oil clearance check on a newly rebuilt engine, excessive clearance is discovered. This could be due to dirt on the block or the main bearing parting halves. It takes only a small film of dirt left from the hot tank, bake oven, or shot-peening process to increase the oil clearance by 0.001" or more.
- When using a reground crank and new bearings, check the main and rod bearings for proper clearance and to be sure that the right bearings are being installed.
- Remove the crankshaft and install the rear main seal.
- Be sure to offset the parting lines on a two-piece seal.
If a rope seal is installed too tightly, heat can cause the rear main bearing to seize. The seizure will occur on the rear part of the bearing.
Although it was commonly recommended in the past, Fel-Pro Inc. recommends that rope rear seals not be soaked in oil before installation. Soaking of the wick can cause it to disintegrate. Some of the seal's graphite impregnation might be lost. Lightly lubricate the seal with chassis grease to avoid damage from a dry start up.
- Tighten the main caps.
Install the main bearing caps, making sure they are matched to the box and face the correct direction. Reprinted with the permission of Ford Motor Company.
- The main bearing caps must be installed to the correct saddle.
- In addition, the cap must be installed in the proper direction.
- Failure to follow these precautions can result in early bearing failure, crankshaft failure, or engine noises.
- Align the thrust bearing halves.
- After aligning the thrust halves, check crankshaft endplay with a feeler gauge or a dial indicator.
Checking crankshaft endplay with a feeler gauge. Courtesy of Federal-Mogul Corporation.
Checking crankshaft endplay with a dial indicator. Courtesy of Ford Motor Company.
Crankshaft endplay is controlled by the thrust bearing. Endplay tolerance is usually from 0.004"-0.006" for a crankshaft with a 2" to 2 3/4" main bearing diameter. If crankshaft endplay is too great, oversized thrust bearings or inserts may be available.
- Assemble the piston and piston rings.
- Install the rod bearings.
- Install the piston and rod assembly into the block.
- Check the installation of the piston and rod assembly.