[Public-List] Rear Oil Seal Replacement on Atomic 4

Sat May 2 11:21:10 PDT 2020

Thanks, Clay! Your article is now posted on 
http://alberg30.org/maintenance/MechanicalPropulsion/Atomic4/Oil_Seal_Replacement.html 
to help future Atomic 4 owners.

  - George

On 4/30/20 9:24 PM, George Dinwiddie via Public-List wrote:
> Clay, the mailing list strips binary attachments, including photos, to 
> prevent the spread of malware. If you'd like to send them to me directly 
> at webmaster at alberg30.org, I'd be happy to combine them with this post 
> into a page on the website.
> 
>   - George
> 
> On 4/30/20 8:33 PM, Clay Pass via Public-List wrote:
>> Here's a little write up I did explaining my process for rear oil seal
>> replacement on the Atomic 4 for those that have pesky oil leaks from
>> "somewhere in the back of the engine".  I thought it might be useful
>> information.
>>
>> So, I had promised to post about the "great rear oil seal replacement 
>> job"
>> on my Atomic 4.  I finally feel like I’ve beaten this oil leak gremlin to
>> be able to declare victory.  First a recap … oil was leaking from the 
>> rear
>> of the engine, but only while running AND in gear.  I visually eliminated
>> the oil pan gasket and two other common sources of leaks, the valve cover
>> and oil pressure regulator.  Both of these areas were dry and there 
>> was no
>> trickle back found on the cast iron mounting flange of the engine leading
>> to the rear.  Also the volume of oil leak was A LOT while in gear, so the
>> obvious source was the seal on the output shaft.  Hopefully you have a
>> large access panel in your cockpit to reach this area, because this would
>> be a difficult if not impossible task to do otherwise without pulling the
>> engine.  Gaining access, you first unbolt the propeller shaft from the
>> output coupling and slide the shaft aft as far as it can go.  I first
>> marked across the flange/coupler with a sharpie because I wanted to
>> reassemble with the exact same alignment, just in case.  Sliding the 
>> shaft
>> back was a little difficult because my cutlass bearing and packing were
>> recently replaced so it was a little tight.  I used a little grease on 
>> the
>> shaft to help and a pry bar to help move things aft.  Luckily, no leaks
>> resulted as this was done in the water and what I thought was going to 
>> be a
>> couple of hour job turned into several weeks!  Who knew?  L.  Also 
>> remember
>> to move the tiller fully to one side to allow enough room for the 
>> propeller
>> to slide aft without hitting the rudder.
>>
>> When fully aft, there was barely enough room to get a 1-1/8” socket 
>> and ½”
>> breaker bar on the output shaft spindle nut.  I threaded a couple of the
>> bolts back into the output coupling and put a hefty screwdriver across 
>> them
>> against the hull to keep the shaft from turning while I broke the spindle
>> nut loose.  Remember to bend down the retaining ear of the “lock washer”
>> underneath before trying to remove this nut.  This actually came off 
>> pretty
>> easily.  Remove the washer underneath.
>>
>> Next the fun part, I used some slightly longer 3/8” fine thread bolts
>> threaded through the coupler holes until they pushed on the flange 
>> casting
>> underneath.  Tightening each successively pushed the coupler off the 
>> shaft
>> after a hour or two of tedious tightening with a box end wrench, because
>> there wasn’t room enough for a socket and ratchet (boo!).   The bolts 
>> I had
>> weren’t quite long enough to push it all the way off, so at the last 
>> little
>> bit I had to back them out and put a screwdriver or some spacer 
>> underneath
>> to be able to push a little further.
>>
>> With the coupler removed, the seal is right there, exposed in the opening
>> of the mounting flange.  Logic would suggest that a simple pry with a
>> screwdriver would pop it right out.  Having a spare engine at home in the
>> garage proved this point.  The attached picture shows how I practiced 
>> this
>> concept at home and sure enough, the seal popped right out without having
>> to remove the flange (seal on the left).  For this reason, I did not 
>> order
>> new gaskets for the flange because WHY remove it???    Well, as one 
>> should
>> have known, with the real engine in the boat, it seems like someone must
>> have welded the seal in place and no amount of prying or knuckle banging
>> was going to budge it.  How could such a tiny seal hang on so tight?  
>> I had
>> bought the replacement seal that I had planned to just tap right in, 
>> but no
>> gaskets.  The replacement seal is a National p/n 473227.  There may be
>> other equivalent parts from other vendors being used.  So I ended up 
>> having
>> to remove the rear flange anyway to take home to a vise to pound/pry out
>> the offending seal.  The result is the seal shown on the right in the
>> picture.  It looks like it was removed with a stick of dynamite!  The
>> gasket you need is also shown (you need 2 of these).  Be sure to inspect
>> your coupler for wear at the interface with the seal.  The old seal,
>> instead of being flexible, had aged to hard plastic and will have a
>> tendency to wear a groove into the coupler.  If the groove is noticeable
>> then go ahead and replace the coupler.  These are available at Moyer’s 
>> for
>> about the same price as buying his “repair sleeve”.  The delta is only
>> about $4 so why buy the sleeve?  Anyway, I decided mine was ok and I 
>> reused
>> it.
>>
>> Unfortunately, I now had to order 2 of these flange gaskets and that
>> resulted in the 2-3 week down time (first place I ordered them didn't 
>> have
>> them in stock and put them on backorder).  Buy them from Moyer’s, they 
>> have
>> these in stock.  Lesson learned!  If you can remove the seal without
>> removing the flange then do that and you’ll be  way ahead.  Also consider
>> when you remove the flange it will immediately dump your oil so be 
>> prepared
>> to catch this mess in a pan or something to keep it out of your 
>> bilge!  Also,
>> before removing the flange, I marked its alignment with the engine block
>> with a sharpie so I wouldn’t have to guess upon reassembly since it 
>> looked
>> symmetrical.
>>
>> So reassembly … obviously clean all surfaces of old gasket material and
>> apply the new gaskets.  The rear flange actually comes apart in two 
>> pieces
>> exposing a bearing in the inner plate.  That’s why you need 2 identical
>> gaskets.  I tapped the new seal in place and lightly greased the bearing
>> just because I could.
>>
>> Back at the boat now.  Having been forewarned.  I lightly wrapped some
>> electrical tape around the exposed output shaft and key to cover sharp
>> edges and protect from nicking the new seal when fumbling the flange
>> assembly back on the engine (clean any old gasket material from engine 
>> too).
>> The output shaft is loose and “floppy” when it is unsupported, so use one
>> hand to hold it in position while guiding the flange assembly into 
>> position.
>> After installation, remove your electrical tape.  Next the fun part and
>> lesson learned.  Reinstalling the output coupling on the shaft.  First 
>> use
>> plenty of grease to make this as easy as possible.  Grease both the 
>> shaft,
>> the bearing inner race within the rear flange and both the inner and 
>> outer
>> mating surfaces of the output coupling.  Key to remember is that the
>> coupler is both pressed onto the shaft on its inner surface as well as 
>> the
>> bearing and oil seal on its outer surface, so grease both.  I used the
>> tapping method with a hammer to get the coupler started on the shaft far
>> enough to finally be able to thread the spindle nut and then by 
>> tightening
>> the spindle nut until the coupler was fully seated against its stop.  So
>> here’s the trick … it will seem that progress is being made a little 
>> tap at
>> a time while standing on your head and with barely enough room to swing a
>> hammer when it just won’t go any further and stops just short of being 
>> able
>> to thread the spindle nut on.  The secret is, remember the ”floppy” 
>> output
>> shaft?  You have to support the shaft, slightly wiggling with one 
>> hand, to
>> center the shaft in the assembly while you are tapping the coupler 
>> with the
>> hammer using the other hand.  With much aggressive “tapping” the coupler
>> will slowly begin to move again.  Once the threads are exposed and you 
>> can
>> get your spindle nut on again, the rest is easy.  Use something to 
>> keep the
>> shaft from turning and use your 1-1/8” socket and breaker bar to firmly
>> seat the coupler.  Then remove the spindle nut and install the “lock”
>> washer underneath.  Reinstall the spindle nut and bend up an “ear” on the
>> lock washer to hold in place.  Reattach the propeller shaft using the
>> alignment marks.  Luckily, the shaft pulled forward by hand with a little
>> twisting and pulling perhaps assisted by the grease I had earlier put on
>> the shaft.  The rest was without issue.
>>
>> Remember to refill the oil.  Of course, like I like to overtighten 
>> stuff, I
>> also like to overfill things.  Don’t do that.  During the trial run I had
>> excess oil overflowing from the oil fill spout area.  My fill spout is on
>> the rear of the engine and is probably vulnerable to over-fill issues
>> because of the tilt of the engine.  That is another area to check when 
>> you
>> have oil leak/spillage at the rear of the engine.  However, with all that
>> cleaned up, I can happily report that I have no more oil leaks!  What a
>> blessed day this is!  J
>>
>>
>>
>> Clay Pass
>> #449 Seeing Deep
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