[Public-List] Norscot shaft seal--lip seal replacement?

[Anders Bro via Public-List]

Hi Randy,

You might want to pass by my note here, as I don't have any experience 
with replacing this seal in particular, but I have rebuilt a few 
engines  in which shaft seals are used, and the experience that I 
gleaned from these efforts may be pertinent?

In older engines (think pre-70s), the shaft seals could be string 
packings that were threaded into a cap. Newer engines use a seal that is 
a part of a steel cup that gets pressed into the bore that surrounds the 
shaft. (There is an easier configuration in which the lip seal is a 
rubber piece with no steel can - much easier to remove.) I expect that 
this is what your seal is like? In any case, the first job is to get the 
seal out with a hooked tool (that will definitely ruin the old seal) 
that you can typically get at Napa Auto Parts or some such car store. It 
is a bitch to get it out with the shaft still in place, as if you score 
the shaft, you have permanently made a leaking seal as the shaft is no 
longer smooth in the area of the contact seal. Putting the new seal in 
is pretty easy as long as (this is important) you tap it in straight.

BUT! (isn't there always one?) One old timer who had done a lot of 
rebuilds passed this perspective along to me: Why does a seal go out? If 
everything is aligned and concentric, there is no reason for a seal to 
wear. (The only exception to this is maybe if the seal is not lubricated 
or if it is made of inferior material so that it rots, cracks, etc.) On 
the other hand if the shaft develops some play then the seal will 
eventually leak. So a leak in a shaft seal may be an indication of worn 
bearings. And if you have worn bearings, then a new seal won't last too 
long, and you might be advised to take the unit out and do a thorough job.

In light of this thought, you might want to consider putting a dial 
gauge on the shaft and trying to wiggle the shaft (perpendicular to its 
axis), and if you get more than 0.001" movement (I really don't know 
what the spec would be, so this is a guess on my part) then you might 
want to replace the shaft bearings as well (yes, pulling the tranny - No 
fun :-( ).

I know these thoughts are not specifically directed towards the 3MB, but 
I hope they help you assess your needs.

Do tell us how it goes! (and all power to you)

Anders


On 06/23/2015 08:16 PM, Randy Katz via Public-List wrote:
> Greetings, Albergers,
>
>
> I have a Norscot shaft seal that came with the Universal 3MB 30 diesel
> engine. It's time to replace the seals. (See links and info below.)
>
>
> A couple of questions--
>
>
> 1. I'm wondering, if I simply disconnect the shaft from the transmission,
> remove the old seals, install the new ones, then reconnect the shaft, will
> shaft/engine realignment be required? Is there any chance it will go back
> together as it was so that won't be necessary?
>
>
> 2. Has anyone done this before who might have basic pointers? I know this
> is going to be a major pain, what with limited access and all, but I'm
> willing to give it a shot.
>
>
> Many Thanks,
>
>
> Randy Katz
>
> #249    Simple Gifts
>
> Seattle/Bellingham WA
>
>
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>
>
> <http://www.norscotshaftseal.com/index.html>
>
> http://www.norscotshaftseal.com/index.html
>
> These seals are good for about 1000 hrs. before they start leaking. (Now
> have 1200+ hrs with leaks of ATF fluid from the reservoir.)
>
>
>
> Video on how to install a PSS shaft seal—very useful for basics of a
> similar process: https://www.youtube.com/watch?v=3UvyF-NRooQ
>
>
>
>
>
>