Crankshaft rear oil seal

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SteveEdmonton
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Crankshaft rear oil seal

Postby SteveEdmonton » 27 Sep 2016 07:13

After 2000 miles the aftermarket oil seal on my L20B is leaking. Nissan is fetching me a new OEM set-- the crankshaft seal itself plus the two side seals-- which I hope will last longer. (See pic below)
Crank seal parts diagram A10 p26.jpg
Crank seal parts diagram A10 p26.jpg (96.81 KiB) Viewed 521 times

The engine is out of the car, so I can pull the pan with no trouble. However, I'm not sure how much further disassembly I'll have to do in order to replace these seals. I'm using the FSM for the L16, not the L20B (below), but I'm assuming the process is the same. And the manual presumes you're doing this as part of a complete rebuild....
Crank seal install 510 eng EM-35.jpg
Crank seal install 510 eng EM-35.jpg (85.12 KiB) Viewed 521 times


Specifically: Is there a way to remove the leaking crank seal, without disturbing the bearing cap?

And what about the side seals? They don't seem to be leaking, and I'm guessing I would definitely have to pull the bearing cap to replace them. Should I just leave the existing ones in there?

Finally, if I do have to remove this bearing cap, I'm guessing I'll need to loosen all of the bearing caps, not just this one, right? (I know that means doing them in proper sequence, both loosening and tightening.)
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Re: Crankshaft rear oil seal

Postby Byron510 » 27 Sep 2016 07:23

The rear seal can be pulled out with a hook tool, I've done this a few times myself. It'll take about 10 minutes to pull it out, be care not to score the crank surface in any way. But before you start, make note of the depth of the seal, you want to install your new seal about 1mm or more away from your existing ones position giving the inner lib a fresh area on the crank journal to seal against - just in case there is a groove.

Use a 3/8" extension to tap the new seal back in - it's a perfect size punch tool.

Side seal replacement = removal of bearing cap. There's no way around that one. What I have seen in the past is that when the side seals have been installed, the metal shims have not been tapped flat to the lower oil pan gasket surface. This can also cause a leaking area. The oil pan would have ot come off to check this.

And lastly, should you have to remove the rear bearing cap, you can just remove the rear cap on it's own - no issues. But you shouldn't need to go there to change the seal. The extra stress on the block is not a concern. You worry about this on the head due to the flexibility of the aluminum head. In the block, the crankshaft floats in clearance within the bearing journals anyways. How much could that cast iron move? It's not like it will run in the condition, and you'd have it all torqued back to spec anyways, so you are good to go in my mind.

My thoughts on your subjects anyways.

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Re: Crankshaft rear oil seal

Postby 510wizard » 27 Sep 2016 08:03

Also, if you are installing the new side seals, don't goop to much sealant into the side seal groove and on the side seal itself, because it will cause the seal not to go into the groove all the way to the bottom(sealant builds up in the bottom of the groove). The side seal must be flush with the pan mating surface.

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Re: Crankshaft rear oil seal

Postby Three B's Racing » 28 Sep 2016 05:12

I've used to always leave the side seals ever so slightly above the bearing caps surface so when everything is torqued down it would seal against it's mating surface. I would place two .010 feeler gauges on the surface and run a blade on it shaving it to .010" above the bearing caps surface. Seems to have work as I never had a leak in that area.
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SteveEdmonton
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Re: Crankshaft rear oil seal

Postby SteveEdmonton » 28 Sep 2016 07:06

Excellent advice from all, thanks very much.

I'm a little surprised to be facing this issue because of the very low mileage on the engine (2000 miles). Was it a quality issue? The motor was assembled by a shop I trust, so I expect they would have checked for a groove in the crank and positioned the seal appropriately (as Byron suggests). I'd also think they would have measured / installed the side seals appropriately (Lou, and 510Wizard). On the other hand, the seals are aftermarket, National brand, and maybe that contributed to their failure.

Anyway, that's all guesswork, and beside the point right now anyway. I appreciate the help in installing these new Nissan seals well, with the goal of avoiding this issue in the future.
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Re: Crankshaft rear oil seal

Postby SteveEdmonton » 01 Oct 2016 08:10

A little wrinkle: the seal is a little trickier to remove than I had expected. Tried to pull it out with a hook inserted next to the crank-- taking care not to scratch it!-- but no movement at all. Wasn't able to insert the hook anywhere else, or a screwdriver either, due to the much more "solid" construction of this seal, compared to what I expected. I thought it would be mostly rubber, not metal.
IMG_8359 comp.jpg
IMG_8359 comp.jpg (187.81 KiB) Viewed 422 times

If I pull the oil pan, then bearing cap, I'm sure it would come out without too much problem. But I'm still trying to avoid all that extra work. So my current idea is to drill a hole in the metal ring part of the seal, insert hook, pull.

Or, if that doesn't work, enlarge the hole so that it cuts through the ring completely, then grab one end and pull.

Does this make sense?

One more thing. If you look closely you'll see that the outermost bits of the bronze input-shaft bearing are eroded away. I think I must have damaged it when installing it. However, I'm guessing there's no real harm in continuing to run it in this condition, since the bearing surface itself is fine and the crumbling isn't likely to continue.
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Re: Crankshaft rear oil seal

Postby Byron510 » 02 Oct 2016 07:49

You'll need to get rough with that seal the easiest thing to do is literally puncture the back metal face of the seal, giving you a hole to pot your book tool into, and then pry it out. A hole can be made by striking a flat screw driver through the seal. Or I have heard that guys have run a screw into the back face and pried on the screws. I've not tried the method, but I would think it would also work.

Hope that helps.

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defdes
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Re: Crankshaft rear oil seal

Postby defdes » 02 Oct 2016 07:57

Or depending upon the thickness , you could drill a few holes and use a slide hammer with a hook or a self tapping screw.

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Re: Crankshaft rear oil seal

Postby SteveEdmonton » 02 Oct 2016 15:26

Your tips encouraged me to "go after this"-- but unfortunately I've given up. :(

Partly this is because this seal is in there far more solidly than I expected. As you can see, I've done serious damage to the seal while trying to pry it out. But it hasn't budged. And I really don't want to damage the crank, or do any more damage to the part of the block right next to it, that the screwdriver shaft has been working against (to the right of the destroyed section).
IMG_8374 comp.jpg
IMG_8374 comp.jpg (184.07 KiB) Viewed 386 times

I also did something I should have done before even starting this job-- that is, reading the section on replacing this seal in the "How to Rebuild Your L-Series Motor" book. It's more detailed than the FSM I excerpted above. And it makes me realize that even if I get this old seal out, it's still quite a bit trickier to get the new one in than I expected.

So the motor is strapped onto a dolly now awaiting transport to the shop that rebuilt it. I'm going to have them deal with it from here. Not at all what I was hoping for, but I've sort of come to the end of the road here. Man, I hate it when this happens!
IMG_8375 comp.jpg
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Re: Crankshaft rear oil seal

Postby Byron510 » 03 Oct 2016 07:00

If you still have the engine at home, you could still give this a go. The part of the seal that give it the most seat pressure is the outside steel band, currently pressed against the outside diameter of the bore. Since there is now space, and if you can collapse this inward, it would relieve this pressure and the rest of the seal would be much easier to extract.

I hear you in not wanting to damage any part of the block or crank. You are right to be careful.

Regardless of how and where the seal comes out, I do suggest cleaning the paint off the seal journal on the crank. This same diameter is also the flywheel register. It should not have paint on it. Also check for nicks or burrs on the entire surface before installing a new seal as it doesn't take much to hurt that inner lip on the seal, if you look at it the lip is a fairly delicate surface. A polish around the surface with a scotchbrite pad finished up with a very fine emery cloth (2000 grit) is recommended to clean and prep the surface and give the next seal a chance. The mark I see just past the 12 o'clock position could be enough to damage the seal if the seal is also initially pressed on at a bit of an angle. If you can be present to make sure this prep all happens, it would give you piece of mind for sure.

Hope it all works out. Keep up posted.

Byron
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Re: Crankshaft rear oil seal

Postby Three B's Racing » 03 Oct 2016 08:36

I'd replace that pilot bushing in the back of the crankshaft. I mean it's broken and who's to say you don't have any stress fractures plus its only a few dollars for a new one. I've used three self tapping screws 120degs apart carefully pulling at each one a bit at a time until the seal starts to move. Granted some seals get really stuck in there but it'll go.
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Re: Crankshaft rear oil seal

Postby Byron510 » 03 Oct 2016 10:08

It's a bit of a foot note at this point, but I'm sure you punched up these vids on You Tube. The first was the crew method mentioned earlier, and the slide hammer method followed;

https://www.youtube.com/watch?v=ri8xnBnF4yk

https://www.youtube.com/watch?v=VdxSe2da30A

Here is a supper easy way to remove the pilot bushing, using grease. I've done this many times, just machined up a piece of steel to fit the hole and popped the bushing out. But what if you 're like most people and don;t have a lathe sitting beside you? Apparently tape is your friend. I found this reference vid pretty funny - so I'm posting it here;

https://www.youtube.com/watch?v=UXi3oeWX1Bg

Here's another variant while on crazy methods - no grease - use wet paper!....;

https://www.youtube.com/watch?v=fA0HdO__AQA

And apparently Wonder bread has a way more useful place in our world (and none of the wheat bread as noted by the vids creator);

https://www.youtube.com/watch?v=UfHds5zEyHY

So, bottom line, you can get that bushing out in 10 minutes with one of these methods for sure :-)

Take care.

Byron
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Re: Crankshaft rear oil seal

Postby SteveEdmonton » 03 Oct 2016 11:19

Good news, the old seal is out and the new one is in. It took all of 5 minutes.

As soon as I saw where Ken applied the screwdriver, "versus" where I was doing it, it was obvious why my method didn't work and his did. I was working "horizontally" in the middle of the metal strip, prying against the crank hub (bad idea) or, from a long distance, the block. That achieved nothing. Ken worked straight in alongside the block, still with the screwdriver blade horizontal but prying "vertically," from a very short distance away, and of course out it came in a moment. I had been afraid to do that, lest I push the steel band into the crank and scratch it.

Yet another place in the road where it becomes obvious that I'm a theologian, not a mechanic.... Though in this case neither praying nor cursing had helped much!

Byron, yes we certainly did clean up the little burrs on the crank that you can see in the photo. Even for me, they were an obvious problem. Unfortunately we didn't follow up with Scotchbrite or 2000 grit on the sealing surface, and now the new seal is installed. I'll try to remember those good suggestions for next time-- while continuing to hope, of course, that there won't be a next time (at least on this motor).

Paint on the crank-- yes, good catch, I'll clean that up. It was sloppy of me to have let that happen the first time around. :(

Lou, I'd rather ignore the pilot bushing and hope for the best but you're right, it would be kind of stupid to leave it while everything's already apart. I've taken these bushings OUT before and never had a problem. I think I used a hacksaw blade last time, just sliced it (carefully) and out it came.

Where I obviously did have a problem though was in putting the new one IN. What's the skinny on that process? What I remember from last time was soaking it overnight in oil, then just tapping it in. But that's what crumbled the outer end, creating this mess. How can that be avoided? (I don't have any manuals handy at the moment, to check what they would recommend.)
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Re: Crankshaft rear oil seal

Postby Byron510 » 03 Oct 2016 12:13

When installing the bushing, using something that supports the entire face of the bushing is best. So if that happens to be a socket, make sure it has a square end, and out it on an extension so that you can see that you are tapping it in level. the best installation tool will sit perfectly in the bushing ID, and have a perfect seat against the whole axial face of the bushing - hard to go wrong with that, but you'll likely need a machinist to turn you up such an animal.

Glad you are out of the woods, nothing worse than being frustrated.

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Re: Crankshaft rear oil seal

Postby greenthumb » 03 Oct 2016 12:37

it'd probably help to put that pilot bushing in the freezer overnight before you install also...


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