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Replacing the Rear Main Seal in my '49


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With the prospect of the weather starting to warm I'm getting excited about getting to the rear main seal on my 288. I was losing about a quart of oil in sixty miles of driving when I put the car away for winter.

<span style="font-weight: bold">Question #1</span> - is there a better seal available than the original wick seal? If not, I'll just do that. I've never done anything like this before and it ought to be quite an adventure.

I welcome any advice from any that have done this!

It has been recommended to me that I take the opportunity to plasti-gauge my rod bearings while I have the pan off. I've read enough to understand how plasti-gauge works, but am not quite sure to do with the results...

<span style="font-weight: bold">Question #2</span> - Based on what the plasti-gauge reveals, what do I do? I see that rod bearings are available in 001, 002, 010 and greater sizes from Kanter.

<span style="font-weight: bold">Question #3</span> - Do I need to plasti-gauge each rod bearing, or just one?

I think that's enough questions! I welcome advice from this group, knowing that some of you have done this kind of work many times. This will be my first time and I don't want to get it wrong.

Thanks so much,

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While I wouldn't call replacing the wick seal a fun job, properly done it's a very effective seal and would no doubt last for the better part of 100,000 miles w/o problems. I'm not aware of any replacement type but that doesn't mean there isn't one.

Plastigaging one rod will show you the oil clearance on that rod; to be completely informed about the rod bearing conditions you should examine and plastigage each. There is always the possibility of prior engine service which turned one or more rod undersize, or of some other malady with one bearing and not the others.

If the clearance is excessive, the first thing to do is to determine if the present bearing is standard or already an undersize. The next thing is to determine the condition of the crankshaft journal because if it isn't bright, free of surface defects, and round to within 0.001" (one thousandth)top-to-bottom, left-to-right, and front-to-back, bearing replacement isn't going to solve any problems. If the crank journal is in good shape you can test the assumption that the excessive clearance came from the bearing wear and not the crankshaft, so buy one replacement bearing in the same size, install and plastigage again. If the original bearing was standard and a new standard one shows excessive clearance, using an undersize might give acceptable results though it's not the ideal solution.

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There isn't a better seal for your engine as far as I know.

Replacing the seal is quite a job. The problem is to stuff the upper half into place. During a rebuild this would be put in before the crankshaft but of course this is impossible with the engine in the car.

You have to stuff it in there the best you can. There used to be a special tool for this. It resembled one of those Chinese finger traps we used to play with as kids.

The tool was a cylinder of fine wire mesh. You could grab the end of the seal with it, feed it thru the hole and use it to pull the seal into place.

In the end you do the best you can and cut off the excess.

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The tool you need is a "sneeky pete" which is really a set of tools, one looks like a corkscrew to hook into the upper seal to pull it out, and another one is a wire with a clamp on one end to pull the new seal throught while turning the crank. you also have to soak the new seal in oil befor you install, also check there is a drain hole in the bottom of the rear main bearing cap below the oil slinger that allows the oil to drain back into the pan.. If you pull any of the mains or rod bearings make sure the caps go back on the same way and the tab in the shell is lined up proper in the cap. check the jornals by running you finger nail (or penny, should not leave a copper mark) across the face if it grabs at all the jornals should be checked more closely and possably turned or polished before new bearings are installed..

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OK, I bought a Sneaky Pete. I see how its used. Pretty good idea!

I'd like to raise the engine a little bit to make removing the oil pan easier. I had the oil pan off once before without doing that and it was a real bear. Is there a save place under the engine to use a jack? Or do I need to use some sort of hoist the raise the engine a few inches?

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jay Faubion '49</div><div class="ubbcode-body"> Is there a save place under the engine to use a jack? Or do I need to use some sort of hoist the raise the engine a few inches? </div></div>

I'd suggest a hoist as there is very little clearance between the pan and the rod throw. Any inward deformation of the pan can cause the rod cap to contact it (ask me how I know) grin.gif . If you use the front pulley you won't be able to rotate the crank as needed to install the seal. A piece of angle iron attached beneath two or the head nuts works well.

Have fun! smile.gif

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Yep, since you need to remove the pan, a Hoist is the only Safe way to do it. Since you only need to raise it a little, a low cost engine-hoist will do the job. Even tho the legs that go under car are kinda in the way when working on bottom-end. You may be able to guide it in over left fender, instead of over grille, which will give good access to pan from right side. If not, you may have to remove the hood also, since it has the side-hinged type hood.

Of course an overhead A-frame type hoist is the best, if you can Swing-It. grin.gif But you will definitely have to remove the hood, using one of those.

I've never removed a side-hinged hood from a Packard, but It doesn't look it would be any Fun. smirk.gif (like maybe a neighborhood project)

I like this type, since it is Foldable for storage:

http://www.amazon.com/Torin-Big-Red-Foldable-Leveler/dp/B00026Z3C2

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Rent a hoist from a local rental center. I wouldn't go under a car with a block of wood holding the engine, particularly not one as heavy as a straight-8. Even if you're only going up a little bit, a hoist is the best way to go to prevent damage as well. If you don't want to use head bolts, get nylon straps that you can sling under the engine to distribute the weight. A block of wood on a jack sounds like a recipe for trouble. Rusty Otoole's idea of blocks of wood between the mounts and the engine sounds like a very good idea, though.

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Matt Harwood</div><div class="ubbcode-body">Rent a hoist from a local rental center. I wouldn't go under a car with a block of wood holding the engine, particularly not one as heavy as a straight-8. Even if you're only going up a little bit, a hoist is the best way to go to prevent damage as well. If you don't want to use head bolts, get nylon straps that you can sling under the engine to distribute the weight. A block of wood on a jack sounds like a recipe for trouble. Rusty Otoole's idea of blocks of wood between the mounts and the engine sounds like a very good idea, though. </div></div>

I wouldn't go under there and work on it either.

I use a hydraulic jack to lift the engine. The block of wood, usually a piece of 2X6, goes between the engine pan and jack to protect the engine pan from damage.

After lifting the engine up I put blocks between the frame and engine, in such a way that there is NO WAY the engine can come loose even if you hit it with a sledge hammer.

Then, take out the jack and go to work.

Obviously you can't take off the oil pan while there is a jack and a wooden board underneath it holding the engine up.

By the way I tend to be VERY safety conscious and recommend everyone else do the same.

In over 40 years of working on cars have suffered no injuries other than flesh wounds and the loss of lung capacity from asbestos, dust, paint fumes etc.

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By the way, even if you use an engine hoist please don't depend on it!

Block the engine up with wooden blocks between the engine and frame, in such a way THERE CAN BE NO MISTAKE ABOUT IT!

When you get busy you will be prying on the oil pan, wiggling it off the engine and out. There will be some jostling of the engine plus, we never seem to allow quite enough room to clear the oil pump!

So be careful and have a backup safety system don't depend on just the hoist or engine lift.

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Thanks to everyone who responded to my questions on this thread. What a big help.

Last question... After I Plastigage my rod bearings what clearance am I shooting for? The factory manual says "If the clearances are less than .0005 inch or more than .0025 inch, select a new bearing shell to provide the desired clearance."

So do I buy a bearing that will bring it as close to .0005 as possible, or what?

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This can be a little tricky. The journal may have been machined down as part of a rebuild some time in the past.

As long as the journal is not worn a new bearing of correct size should give you the correct clearance. A journal that is rutted and chewed up or worn so far a new bearing has too much clearance means it's rebuild time.

You should also mike the bearing in 3 places to make sure it is not worn oval.

The journal could have been turned .010 undersize, or possibly .020, replacement bearings are available in .010 steps. So you would need to measure the journal to be sure you get the right size bearing anyway.

Here is a clue about bearing wear: if the gray babbitt is worn off down to the copper anywhere, the bearing is worn out.

Another clue: If the top of the bearing is more worn the engine has been lugging in other words working hard at low speeds and full throttle.

If the bottom bearing is more worn the engine has been revving at high speed. Maybe you should slow down a tad.

You should polish the journal with a leather bootlace and a piece of crocus cloth before putting in the new bearing.

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jay Faubion '49</div><div class="ubbcode-body">

So do I buy a bearing that will bring it as close to .0005 as possible, or what? </div></div>

No, Try to get around .002

I've found that under .001 is too tight, (doesn't allow for out-of-round tolerances).

And over .003 is too much.

And that's with the Caps torqued down to about 50% of the final torque. You don't want to torque them all the way while doing the gap testing.

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The engine components are machined to fit the bearing sizes that are available, and you try to end up with .002 clearance between them (or difference between them).

With .002 difference, and If the crank-journal is centered in the bearing, the actual gap would be 'close' to .001, around the circumferance. It's 'close' because of the Out-of-round condition that is always true with 2 piece bearings being crushed together when torqued.

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That is what I am saying. If you check your engine and the bearing is "loose" all you can do is try another standard size bearing. Or if the engine has been rebuilt, another bearing of the same size.

If the new bearing is too big you are beat. Time for a rebuild.

Likewise if the journal is worn egg shaped, rutted,or chewed up.

I also agree that when the engine is running the oil takes up the clearance as long as it isn't too big.

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Ah, Yes, I forgot we were Not talking about a bottom-end Rebuild ??? Or are we ???

Jay,

Were you thinking about replacing bearings without doing any machine work to the crankshaft? If so, I would not recommend it.

Or are you just trying to determine the condition of what you have, when doing the plasti-gauge test, To deside what needs to be Done and learn about the requirements? Which is what I think we were talking about originally.

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Yes, I have planned to replace bearings, as required, without removing the crankshaft. I need to replace the rear seal and wanted to take advantage of having the pan off and having the connecting rods accessible.

Is this really the wrong thing to do? There's no way in the world I could start down the road of rebuilding the engine.

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Yes, I have planned to replace bearings, as required, without removing the crankshaft. I need to replace the rear seal and wanted to take advantage of having the pan off and having the connecting rods accessible.

Is this really the wrong thing to do? There's no way in the world I could start down the road of rebuilding the engine.

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