GM 10146900 Crankshafts

Use a scraper, stone or file to eliminate all the burrs from the oil holes in the crankshaft; this is equally important; at the same time, chamfering them will remove any sharp edges that might damage new bearings. Examine the main and connecting rod bearing journals for uneven wear, scoring, pits, and cracks. To ascertain its condition, rub a penny across each journal several times-if copper rubs off it and adheres to the crankshaft, the journals require regrinding. If possible, use solvent to clean it before drying it up with clean compressed air. The rest of the crankshaft needs to be magnafluxed for hidden cracks-this should be done by an automotive machine shop. Use a micrometer to measure main and connecting rod journal diameters while taking measurements at different points around each circumference to determine roundness of out of roundness. If damaged, tapered, out-of-round or worn beyond specified limits in specifications given have the automotive machine shop reground your crankshaft.Check both oil seal journals at either end of the crankshaft for wear or damage. In case there are grooves on the journal worn by seal's rubbing or it is nipped/scratched then when again putting back together engine there may be leaking from new seal.Repairing this shaft can sometimes involve pressing on a thin sleeve at an automotive machine shop.If not possible replace with a new or used one replacing.Quad-4 engine builders must inspect their oil pump drive gears for signs of wear or damage.If you need a replacement you will have to bring your crankshaft to a dealer service department or an automotive machine shop.The old gear has been drilled and chiseled off while prior installing into an oven was heated up by another new one.Take time as you also do some examination on inserts for both main and rod bearings.

Examine the crankpin and main journal surfaces for scoring, scratches, or corrosion; if any are evident, the crankshaft will need professional regrinding. Use a micrometer to test each journal and crankpin at several different points for ovality, and if it exceeds 0.001 inch, regrinding is necessary. Undersize bearings are available to match the recommended regrind diameter, typically supplied by your GM dealer with the reconditioned crankshaft. After high mileage, main and connecting rod bearings may wear, leading to excessive running clearance, which can be checked using a product like 'Plastigage' after refitting the original bearings and caps and tightening the cap bolts to the specified torque settings. Avoid correcting excessive running clearance by filing the caps; instead, fit new shell bearings after checking the crankshaft journals and crankpins for ovality and confirming their diameters. Checking connecting rod bearings follows a similar method, and it's advisable to check the running clearance of rod and main bearings even with new installations. The crankshaft endplay should be assessed by pushing the crankshaft to the extreme front position and using a feeler gauge at the front end of the rear main bearing. Measure the connecting rod side-clearance with a feeler gauge between the connecting rod caps, and if it falls outside the specified tolerance, replace the rod assembly.

The crankshaft and main bearings are best taken out with the engine out of the car and no one must be allowed to touch it unless the engine has been dismantled already. In regard to the main bearings, one must ensure that each of the five caps is labeled to indicate where they are to be inserted in the engine block; if the marks on the con-rods are missing corresponding indentation marks have to be made on the connecting rod caps. The main bearing caps have to be replaced to the previous positions likewise. Loosen the main bearing caps and identify the crankshaft and carefully remove each bearing cap and the bearing together with it and put them on a clean and labeled working platform nearer to the crankshaft block in accordance with the numeration given to the bearings. Next, raise the crankshaft off the engine block being very careful not to cause any harm to the crankshaft. Both halves of the rear main bearing oil seal must be taken out and the main bearings must be pulled out of both the cylinder block and the main bearing caps but they must be kept separated according to their places. The crankshaft gear at the front can be 'unscrewed' by using a particular puller that would give a crankshaft an appearance of being screwed out of the engine block.

The crankshaft can only be removed after the engine has been taken out of the vehicle, assuming that the flywheel or driveplate, crankshaft balancer/vibration damper, timing chain, timing gear, oil pan, oil pump, and piston/connecting rod assemblies have already been detached. For Quad-4 engines, the rear main oil seal housing must be unbolted and separated from the block prior to crankshaft removal. Before proceeding, check the endplay by mounting a dial indicator with the stem aligned with the crankshaft and touching one of the crank throws. Push the crankshaft to the rear and zero the dial indicator, then pry it to the front and check the reading; the movement indicates the endplay. If it exceeds the specified limit, inspect the crankshaft thrust surfaces for wear, and if none is found, new main bearings may resolve the issue. If a dial indicator is unavailable, feeler gauges can be used by prying the crankshaft to the front and measuring the clearance between it and the thrust main bearing. Ensure the main bearing caps are marked for their locations, numbered consecutively from front to rear, and if not, mark them appropriately. Loosen the main bearing cap bolts gradually until they can be removed by hand, noting any stud bolts for proper reinstallation. Gently tap the caps with a soft-face hammer to separate them from the engine block, using the bolts as levers if necessary, and take care not to drop the bearing inserts. Finally, lift the crankshaft out of the engine, ideally with assistance due to its weight, and with the bearing inserts in place, return the caps to their original positions on the engine block and tighten the bolts finger tight.

Clean the crankshaft with solvent and dry it with compressed air if available. Check the main and connecting rod bearing journals for uneven wear, scoring, pits, and cracks. Rub a penny across each journal several times; if copper rubs off and is embedded in the crankshaft, the journals should be reground. Remove all burrs from the crankshaft oil holes with a stone, file, or scraper to ensure the oil holes are chamfered, preventing sharp edges from gouging or scratching the new bearings. Inspect the rest of the crankshaft for cracks and other damage, and have it magnafluxed to reveal hidden cracks at an automotive machine shop. Measure the diameter of the main and connecting rod journals with a micrometer, comparing the results to the specifications, and check for taper and out-of-round conditions by measuring at several points around each journal's circumference. If the crankshaft journals are damaged, tapered, out-of-round, or worn beyond the specified limits, have the crankshaft reground by an automotive machine shop, ensuring the correct size bearing inserts are used if reconditioned. Examine the oil seal journals at each end of the crankshaft for wear and damage; if grooves, nicks, or scratches are present, the new seal may leak upon reassembly. In some cases, an automotive machine shop may repair the journal by pressing on a thin sleeve, but if repair isn't feasible, a new or different crankshaft should be installed. For a Quad-4 engine, check the oil pump drive gear for wear and damage, and if replacement is necessary, take it to a dealer service department or an automotive machine shop, as the old gear must be drilled and chiseled off while the new gear should be heated in an oven prior to installation. Examine the main and rod bearing inserts.

Carefully lift the crankshaft out of the engine. It may be a good idea to have an assistant available since the crankshaft is quite heavy.

The first step is the installation of the crankshaft.

Check the crankshaft endplay with feeler gauges or a dial indicator, ensuring it is correct if the thrust faces are not worn and new bearings are installed.

Install the flywheel to facilitate engine rotation during reassembly.