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Rear Crank Cap Removal


bfsnail

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So I'm trying to remove the rear cap for the crank and have been following the directions in the Datsun engine rebuild book and for the life of me can't get it out. I've done the whole thread the bolt into the cap and use a block of wood and a prybar to get it out, but to no success. Also tried hitting it with a rubber mallet while prying as well as lubing it all up with liquid wrench to no avail. Any other tricks you have used to remove it?

 

I also noticed today that the two "keyholes" on either side of the cap are filled with a black rubbery substance and a very thin metal rod... I have a bad feeling it doesnt come from the factory like this. Ideas?

 

You can see the keyholes, rubber and rods below.

 

IMG_20110226_152024.jpg

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This is normal.

 

That black rubber with the metal wire is a seal on either side.

 

You see the middle with the hole that is threaded? Thread a slide hammer into it and pull it out straight up. Its hard to find a slide hammer with the correct thread pitch so you will have to rig an adapter more than likely, but this is how I do it. It being tight is a good deal and prevents leaks. You will need to buy new seals and replace the old ones including the black rubber with the wire on both sides.

 

Putting it back in straight with the new seals is the PITA! Get it cocked and you risk damaging the surface where it seals.

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If you search for slide hammers on ebay, theres a great custom made one that some guy makes that threads into the back of vice grips. Comes in several sizes, and is relatively cheap (like $30-$40). Screw the appropriate size bolt into the main cap, lock the vice grips onto it and slam it out.

 

Unfortunately, I don't have one. I had to lever the cap out like the Datsun book says. I used a pickle fork and some pieces of wood to isolate it from the oil pan gasket surface while I levered the bearing cap out, constantly repositioning it to make sure it came out at the right angle. It was a pain.

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You can also fabricate your own main cap puller. Get a long piece of aluminum/steel/whatever that will reach the width of the block. Drill holes that will line up with the 2 threaded holes in the cap that are used for the oil pan. Then on the outer ends, drill a hole on each end and tap it for whatever thread you want.

 

To use your puller you will bolt it to the oil pan holes on the main cap. Then on the outside holes, start wrenching the bolts through. The bolts should come out the other end of the puller and start touching the oil pan gasket surface. As you start to wrench it down more, the puller will lift up therefore lifting the cap with it.

 

The one I made is a little block of scrap aluminum probably 1/2" thick.

 

For compatibility you can get a longer piece of metal and drill another hole between the two drilled for the rear main, and on the outer ends, drill two more and tap them. This way you have one puller with the correct measurements to pull the rear and the center main.

 

zml6cw.jpg

 

2gxl98p.jpg

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I used the engine hoist to pull the bearing out, I think I used a old water pump bolt in the threaded hole in the cap. Put the bolt thru a hole in the chain with a washer so the bolt does not slip thru, thread into the hole in the center of the cap. Start jacking it up, tap the bearing side to side, repeat this process until it comes out.

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All you need is a long bolt, a large washer, crow bar, and some wood blocks. Lay the blocks on the oil pan gasket surface and use them as a pivot point for the pry bar. Arrange the blocks so they aren't sitting on top of the bearing cap. Think like you are pulling out a long nail. Pry straight up.

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You can also fabricate your own main cap puller. Get a long piece of aluminum/steel/whatever that will reach the width of the block. Drill holes that will line up with the 2 threaded holes in the cap that are used for the oil pan. Then on the outer ends, drill a hole on each end and tap it for whatever thread you want.

 

To use your puller you will bolt it to the oil pan holes on the main cap. Then on the outside holes, start wrenching the bolts through. The bolts should come out the other end of the puller and start touching the oil pan gasket surface. As you start to wrench it down more, the puller will lift up therefore lifting the cap with it.

 

The one I made is a little block of scrap aluminum probably 1/2" thick.

 

Awesome idea! I might have to try that if this slide hammer isnt working out...

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You can make it out of any scrap metal you have so long as it doesn't bend easily. The ones I have are only about 1/4" thick but you can also use angle iron.

 

Another way to get around having to tap holes (if you use a thin piece of metal) is to just drill 4 holes untapped and on the outer holes that you would have originally wrenched down, instead put long bolts through with a nut on the underside.

 

This nut will allow you to adjust the height of the puller. By doing so you adjust it first to be 1/2" or whatever above the main cap. You then thread in the oil pan bolts. As you wrench them down they will pull the cap up. Once they have bottomed out or once the cap has been lifted to the point where you're tightening the puller and cap toghether then go ahead and loosen the bolts. Then thread the nuts on the outer bolts up some more, raising it another 1/2", and repeat the process. If you have bolts that will thread into the oil pan holes that are longer (say 1" or more) this will allow you to pull the cap up more before you have to loosen them and raise the puller, since it can get repetitive and annoying sometimes.

 

Note: if you haven't noticed yet a lot of the hardware on the block shares the same thread/size. Judging from my pictures and my amateur eyeball, you may be able to use a head bolt to thread into that main cap hole... If not, you're bound to find something off the block that's the same size. Perhaps an inatke/exhaust manifold bolt or something.

 

Edit: from the picture I posted it looks like the two oil pickup bolts may work.

Edited by josh817
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