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Plastigauge is the name given to a precise method of measuring clearances between bearing surfaces using a plastic material. It consists of a material with precise known dimensions and deformation characteristics. The plastigauge material is sandwiched between the clean bearing surfaces. The dimensional clearance is then determined by comparing the amount that the gauge material has expanded or flattened. Dimensions of better than .oo1 inch can be accurately measured by this method. The material is usually color coded to indicate the range of measurement use for each gauge.
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∙ 16y ago
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What tool is used to check the oil clearance of a plain bearing in a single piece crankshaft?
Plastigauge
Why is it necessary to wipe dry bearing and journal before using a plastigauge when measuring bearing clearance?
You wouldn't want oil to be taking up part of your clearance and give a false reading with the plastigage.
How do you change the oil pump in a 1987 f-150 with a 302?
First, what makes you think the oil pump is bad? If it's just a matter of low oil pressure I suggest that it probably isn't the oil pump, instead I'd look at the rod and/or main bearings. Either case, it will be easy to check when you replace the oil pump. First you have to drop the engine pan. That may require lifting the engine a little off the motor mounts, or it may require removing cross bracing. Whichever is necessary, once the pan is removed you should be able to find the oil pickup. The pickup is connected to the oil pump and the oil pump is usually held in place with 2 bolts, but it may be more. When you drop the oil pump you will probably find a rod that drives the pump. The rod will most likely come out with the pump. Be careful to not turn the rod or the engine until the rod is completely out of the engine. Often that rod connects to the distributor and if you allow it to change position you will have to set-up the distributor again. Replace the pump by going in reverse. But I HIGHLY RECOMMEND that while you have the pan down, you should remove the cap from one or two of the rod bearings and one or two of the main bearings. It would be a good idea to get something called "plastigauge" (or something like that, depending on the brand) It's a little piece of plastic that you lay across a bearing between the babbit and the crankshaft. Tighten down the bearing cap with the plastigauge in place then remove the bearing cap and measure the width of the plastigauge. There will be a chart included with the package to tell you if the bearing is worn too much. I suspect that if you have low oil pressure it is because the babbit is worn from the bearings, allowing oil to seep out around the surfaces. Be sure to wipe down the bearing surfaces before you use the plastigauge so that the oil doesn't give you a false reading. Also, if you pull a bearing cap and find that you have a lot of copper showing on the bearing surface, it's done. Babbit is grey but is backed with copper. once you've worn through the babbit, just rebuild the engine.
Put crank back in a 283 Chevy with the same bearings and main caps that were in it now when the caps are tight the crank will not turn any suggestions?
Probably best to take it back apart, clean everything and try again.I agree with the take it apart and clean it advice. A small piece of grit under a bearing can cause problems.However... I'd either plastigauge the bearings or even better:# Remove the crankshaft. # remove and clean all bearings and put them back in place, making sure that you install the thrust bearing at the right place. # Use a good quality assembly lube on each bearing contact surface. # Clean the crankshaft and lay it into the engine block. # Make sure the crankshaft turns freely. # Install ONE main bearing cap. (naturally, match the bearing cap to it's original home. Most are numbered or otherwise identified) # After the cap is torqued, make sure you can still freelyturn the crankshaft. There should be no resistance other than what is naturally occurring from the assembly lube. It should turn evenly. # Install the next cap following the same directions and verifying that the crankshaft still turns freely. Keep installing one cap at a time until all main bearing caps are torqued and the crankshaft is still turning freely. If you encounter ANY resistance at this stage, the block must be align bored. # Next, install the rod bearings. If the pistons are out of the block, I'd test them by installing them to the crankshaft from the bottom first, just to make sure they're turning freely, then remove them and install the piston properly. Of course, make sure the rod cap is the same one that was originally taken off. Rod caps are matched to the rods when they're manufactured. If you don't put them back right they'll bind.# If any rod bearing does not turn freely on the crankshaft, you'll need to take them ALL to a machine shop and have the rods reconditioned. Sometimes a rod "big end" can pound out of round by a couple thousandths, messing up the fit.
