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Tap crank after rear main replace?

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Old 06-15-2006, 08:37 PM
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Car: '68 corvette '73 Corvette
Engine: 427 454
Transmission: TH400
Tap crank after rear main replace?

Since i have everything off for the head cam swap i decided to replace the rear main seal with a fel pro40013 and a fel pro34510 pan gasket. After searching here and reading my haynes i have a couple of questions.

The manual says the oil pump has to come out and there is a new nylon sleeve in the seal set. After reading many posts on how to replace it i didn't see any that said to remove the oil pump. Does it have to come out and is r&r of an oil pump easy?

In the manual it says to tourque the main cap to 20 lbs. and then tap the crank back and forth to line up the thrust bearing. What is a thrust bearing and does this have to be done.? can i just mark the cap before i remove it?

thanks
Old 06-15-2006, 09:41 PM
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The oil pump is held to the rear main bearing cap with one bolt (or, in my cases, once stud/nut). The pump will hold the oil pump drive shaft up against the distributor shaft. When you remove the pump, the shaft will likely come with it. Forget about the nylon sleeve. Keep it as a spacer for something else, bushing for your lawnmower wheel, or whatever. Install a steel sleeved pump drive shaft when you reinstall the pump for safety.

The rear main bearing includes the thrust bearing surfaces for the crankshaft. The thrust bearing positions the crankshaft axially (longitudally), while the "regular" bearings position it radially. In other words, the thrust bearing keeps the crank from moving fore-and-aft in the case. When installing the rear main cap, lube the bearing surfaces with clean oil, install the cap loosely, and slide the crank fore-and-aft to make sure it is not binding before you tighten the main cap bolts to final torque. Marking the cap won't make a difference. It will only go on in one position due to the dowel. The reason you move the crank is to make sure the crank is not bound, not to position the bearing cap.

And if you're anything like many of us, once you're that close to the main bearings, and if the engine has any kind of mileage, it only makes sense to look at the condition of the main shells and journals.
Old 06-16-2006, 08:58 PM
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Car: '68 corvette '73 Corvette
Engine: 427 454
Transmission: TH400
Thanks for the info. it has less than 20,000 on it with little to no abuse so it should be good to go but i will check them out.
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