Any reason not to re-use a pristine rear main seal?

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I am dropping a replacement 2F into my 40 on Saturday to replace one that is smoking like mad.

I ordered a new rear main seal "just in case" but never pulled the original. I pulled the rear main cap and pulled the rear main seal.

I literally can not tell it apart from the new one..... they look exactly the same. no chips or anything.

it didn't look like it was leaking or anything, I just figured "why not while it's sitting on the stand?" it was a new engine to me and figured it was safer than hoping it didn't leak.

so should I just put the original one back in or should I put the new one in? I know it's cheap insurance to have the new one in there but the old one looks brand new.

engine supposedly has 120K on it or so. Either they were 120K very easy miles or this seal was recently replaced.


also do I need to oil the seal to replace it or just slide it on there?
 
That would be kinda like rinsing a condom out and re-using it........

Oil the sealing surface, or some light weight grease.
 
That would be kinda like rinsing a condom out and re-using it........

Oil the sealing surface, or some light weight grease.

so oil inside surface against the crank? outside surface against the bearing cap dry?
 
Now how hard would you kick yourself in the ass if it leaked? cheap enough part to sleep better at night
 
Now how hard would you kick yourself in the ass if it leaked? cheap enough part to sleep better at night


extremely hard.


reading threads here tonight it seems prudent to also replace the pushrod inspection cover gasket as well. I forgot to order one from CDan (or didn't know more accurately)

hope a local dealer has one, guy coming to help is coming saturday....
 
Rear Crank Seal

I don't think it's an issue to use the old seal if you can tell for sure that it's not worn and it's not "hardened".
Elastometers get brittle and lose flexibility with time.
The best way to install is to remove the bearing cap and slide it in place as opposed to forcing it in the cavity with the cap on - just because you can see it in place.
I believe that the "book" says to put a sealant between the cap and the block where they contact each other so there won't be anything oozing outta the microspace between.
I personally see nothing wrong with putting a silicone sealant all around the outside of the seal.
Toyota sells a pricey black silicon sealant that is my friend in rebuilds.
 
You can use the "Lake Test" to see if the old seal is still good.

The Lake Test:

Step 1: Throw the old part into a lake.
Step 2: If the part floats, it's still good - reuse it.
Step 3: If the part sinks, replace it with a new one.

Try it. It works!

Note: the Lake Test works for just about any old part that is removed from your Cruiser.

;)
 
I ordered a new rear main seal "just in case" but never pulled the original. I pulled the rear main cap and pulled the rear main seal.

I literally can not tell it apart from the new one..... they look exactly the same. no chips or anything.

it didn't look like it was leaking or anything, I just figured "why not while it's sitting on the stand?" it was a new engine to me and figured it was safer than hoping it didn't leak.
You just answered your own question!!!!


so should I just put the original one back in or should I put the new one in? I know it's cheap insurance to have the new one in there
Again you just answered your own question!!!!


If you do use the old seal, what are you gonna do with the new one, throw it in a box someplace? Put in the new one and throw the old one in the box. (trash?)
 
Definitely use a new one. Before oiling the crank surface, it’s a good idea to polish it w/ a piece of emery cloth to make sure there are no burrs.
If you happen to have a TC nose cone, they work well for driving the new seal in:beer:
 

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