Pontiac 10048682 Crankshaft

It is advisable to inspect the end play when an overhaul of the crankshaft is to be done by mounting a dial indicator such that the stem is parallel to the crankshaft and touching one of the crank throws. Rotate the crankshaft to the rear and set the dial indicator at zero, rotate the crankshaft forward and read a value of the end play. If it go beyond the said limit, then check the thrust surfaces of wear; if there is none, then new main bearings may rectify the problem. Incase one cannot find a dial indicator, use feeler gauges, pull the crankshaft towards the front and ease the gauges in between the crankshaft and the thrust main bearing to get the clearance. Remove the main bearing cap bolts an eighth turn at the time until they could be pulled out by hand and the caps are often numbered from front to rear, thus these marks are useful for the proper positioning of the cap bolts. If unlabeled they can be marked by the use of a stamping die or a center punch. As mentioned earlier most of the caps are marked with a cast-in arrow symbol that points to the front direction. Tap the caps lightly with a soft-face hammer to provide the required clearance and you can easily lift the caps off using the bolts and ensure that the bearing inserts are not dropped when doing so. Lastly, remove the crankshaft from the engine and it is recommended to do it with help, then put back the bearing caps to their positions on the head of the engine, tighten the bolts with fingers only.

After high mileage, main and connecting rod bearings may wear, leading to excessive running clearance. This 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.

Next, lift the crankshaft from the engine block, taking care not to damage it.

Gently tap the caps with a soft-faced hammer to separate them from the engine block, using the bolts as levers if necessary, and avoid dropping the bearing insert.

Measure at various points around the journal's circumference.

Clean the crankshaft with solvent and dry it thoroughly, ensuring to clean the oil holes with a stiff brush and flush them with solvent.

Once the crankshaft is confirmed clean, carefully position it in the main bearings, checking the main bearing oil clearance with Plastigage placed on each journal.

If it falls outside the specified tolerance, replace the rod assembly.