Another stuck lower casing cap 1999 F50

[99yam40]

It would be interesting to know for sure what caused the grooves.
with that part of the shaft being so close to the bearings, I do not think it would be possible to flex that shaft that close to the bearings that hold it true.
and motors do not develop there peak HP until they get up to the WOT RPM range, so the motor is just bogging down from the load.

was that motor on a different boat?
if so, maybe the prop was OK for that set up

[ChuckB1954]

It would be interesting to know for sure what caused the grooves.
with that part of the shaft being so close to the bearings, I do not think it would be possible to flex that shaft that close to the bearings that hold it true.
and motors do not develop there peak HP until they get up to the WOT RPM range, so the motor is just bogging down from the load.

was that motor on a different boat?
if so, maybe the prop was OK for that set up

It's a long story.. But yes, this is the second motor on this boat. The original motor for this boat was a 1994 C55TLRS which was a two stroke. I am the second owner of this Key West 1520. After several years, the original motor overheated and scored a cylinder. The owner then bought a second hand motor, a 1999 F50TLR 4 stroke. I don't know the whole history, but when I got the boat, the motor had some problems and was missing some parts, which I corrected. I made a thread in this forum about it. He had been running the boat in this condition for a while loaded with family members. I removed four non original seats after purchasing it. The original non mechanic owner sold the boat to me very cheap because he didn't want to deal with its problems and purchased a new boat. The prop on the replacement 4 stroke motor was too high of a pitch. I then tried the lower pitched one off the original 2 stroke engine, still too high.. I then dropped the pitch value twice.. too low, went up one value and finally achieved WOT at the right RPM's. (32MPH at 5500+ RPM's). That is most of the story anyway.

Again, I don't know the history of my motor, but the only possibilities for those grooves that I can think of are:

1) The flex, as I mentioned
2) Shaft bearings worn out at one time ( They appear to be fine now, but I have not gotten too technical in their testing).
3) This shaft came out of another engine

About a shaft flexing.. I was working on a Harley Evo V-Twin that was throwing the enclosed primary belt from time to time. Come to find out, the inner primary bearing was not fitting tight into the inner primary cover. It was missing an outer adapter ring/shim making the bearing loose fitting and the main shaft of the tranny was flexing causing the belt to walk off. The portion of the tranny main shaft sticking out was short and thick and was right next to a bearing, but it still flexed enough to cause the problem.



When the original owner had it. 55HP, Two Stroke Engine


After I bought it and did some work, 50HP, four stroke engine.

[ChuckB1954]

I was looking at some used drive shafts on Ebay and they have very similar wear.. Maybe this wear is common or normal?

ebayShaft.JPG
ebayShaft2.JPG
ebayShaft3.JPG

[pstephens46]

Marks are marks, grooves have depth. I’m not too worried about marks. Grooves in the seal area of shaft?

[Keithbaja]

Old school trick Replace the seals and move them a few 1000,s in or out. Simple as apple pie

[99yam40]

if you read closely the groves are not where the seals ride on the shaft

[ChuckB1954]

Just an update.. I got it back together and will take it out soon. It went together real nice. I replaced the prop shaft and of course, the lower casing. I replaced the two bearings on the prop shaft/lower casing along with every seal, o ring, gasket and a few other items on the lower unit. If it gets water in it, I will be quite surprised. I ran it in a trash barrel and everything looked good.

20210105_153836S.JPG

The little plastic speedometer nipple (#17) was broke off and being that It was never hooked up anyway, I left it alone. That shouldn't be a leak concern though, right? (I might have asked this before in another thread..)


nipple.JPG

[99yam40]

It should not be a problem, but I would plug the hole where it come in just in case.
but that is just my thoughts

[ChuckB1954]

It should not be a problem, but I would plug the hole where it come in just in case.
but that is just my thoughts

Yes.. I was going to do that, but I forgot. Not really that hard to pull it back off and do it if I decide to.

[99yam40]

I would just plug the small hole where the water comes in on the front edge if it is not already plugged up

[ChuckB1954]

I would just plug the small hole where the water comes in on the front edge if it is not already plugged up

Good idea! I didn't think of that.. That is what I will do.

[TownsendsFJR1300]

Did you pressure test it W/O oil?

That'll let ya know if your successful..

And correct, that speedometer tube (if not clogged), will just spit water up there while underway (it's wet anyway)....

[ChuckB1954]

Did you pressure test it W/O oil?

That'll let ya know if your successful..

And correct, that speedometer tube (if not clogged), will just spit water up there while underway (it's wet anyway)....

No I did not pressure test it.. I can not see how it will leak! It went together great.. I will take it out for a day and check the oil.

As far as the speedo hole, it looks like it is clogged up anyway, but you are right.. the area of the nipple is flooded by water normally, so it doesn't matter how it is left.. plugged or open.




Just took these pictures. Speedo pressure hole. About 4 inches up from the bullet on the leading edge:

speedo.JPG

[ChuckB1954]

Just for future reference.. The arrow shows where the speedometer hose/line is routed after coming up from the nipple. This whole area fills with water, so again, it doesn't matter how the nipple hole is left. That rusty looking tube is the shift shaft. (Things always look worse on camera!)

speedo3.JPG

[TownsendsFJR1300]

Tr00ling again?

I do get a chuckle out of your posts....