Multiple props, same over-rev'ing problem

[EricJRW]

Re: Multiple props, same over-rev'ing problem

I would pull the lower unit and check the water passage above torque tab, this passage feeds water into the exhaust to cool the exhaust and prevent damage to the prop hub. I have seen this a a couple of V-4's that sat in the water all the time. Alos I replaced several units when the "lighting case" came out as hole was to small and caused spun hubs and if unit was on a Ficht seen several melted plastic and rubber hubs due to the higher exhaust temps they ran.

That's very interesting. Although my gut was (apparently) wrong on it being a prop problem (though now maybe not completely), when I looked at the rubber bushing it always appeared to be just a bit melted. Not terribly deformed, just evidence where rubber meets metal that the rubber got hot. It did not seem possible that a submerged prop could overheat, but now I do have something else to look into.

Thanks for that info.

Eric

 

[EricJRW]

Re: Multiple props, same over-rev'ing problem

Hi Faztbullet,

I was looking at the gearcase diagram at http://shop2.evinrude.com/Index.aspx?s1=86fad8460a842fb877d5dcd92d83c8e3&catalog_id=0&siteid=1 (1993, 50, E50BEETB, GEARCASE) and I'm not sure about the "torque tab" you are talking about.

Is there any way you could call out the part number, or mark up a picture, to show me the torque tab?

Attached is a right-click "save picture as" I did of the gearcase diagram (hopefully that's the right area).

Thank you.

Eric

[edit] Well dangit, that attachment does not show up as good here as it does on my computer. Any ideas?

 

[wilde1j]

Re: Multiple props, same over-rev'ing problem

Looks like #70, but the picture is really too small to read well. It's the disk shaped thing with the fin on the bottom and a bolt up thru the center. The fin is the torque tab.

 

[EricJRW]

Re: Multiple props, same over-rev'ing problem

Thank you.

The trim tab (76) seems to match your description, but I'm scratching my head on what it has to do with water in the exhaust.

On the other hand, if it is related, that can be pulled for inspection without removing the lower unit, right? My understanding it's there to compensate for pulling due to... Well I'm not quite sure.

 

[bob johnson]

Re: Multiple props, same over-rev'ing problem

Thank you.

The trim tab (76) seems to match your description, but I'm scratching my head on what it has to do with water in the exhaust.

On the other hand, if it is related, that can be pulled for inspection without removing the lower unit, right? My understanding it's there to compensate for pulling due to... Well I'm not quite sure.

slow down!! ha ha....go back and read faztbullets message again....

the torque tab( trim tab) was just refence of where to LOOK FOR SOMETHING ELSE......

THE WATER PASSAGES!!

look at the water passages above , near , or close to the trim tab....

look inside there for blockage..

the TRIM TAB is just a "navigation aide" ha ha ha...to lead you to what he is telling you about..

once you find the water passages in the LU that MIGHT be clogged, you can forget thinking about the trim tab!!


good luck


bob

 

[EricJRW]

Re: Multiple props, same over-rev'ing problem

Ah, thanks Bob...

That makes more sense, especially when I look at the exhaust housing diagram ("above" as in opposite side). Sure wish there was a way just to blow that out, as pulling the LU is not something I look forward too a) especially at the start of boating season and b) I don't have a trailer. I bought the boat as part of a house purchase, and it's always been hanging in the sling. I have no idea about the trailer, but I guess I could borrow one (might have too).

 

[Faztbullet]

Re: Multiple props, same over-rev'ing problem

Here ya go....

 

[EricJRW]

Re: Multiple props, same over-rev'ing problem

Very nice! Thank you... Guess I still have more work to do.

 

[EricJRW]

Re: Multiple props, same over-rev'ing problem

Oops... I did update, it just was not at the bottom like I thought. :redface:

Anyway, I'm still working on getting the boat out of the water. Since I'd like to service the impeller, it would be the perfect time to inspect the water passage (though the boat stored on a dock, out of the water, when not in use).

I'm surprised I never updated this thread... After all that, especially the multiple props (including a repaired prop) it was a spun hub. Turns out the repaired hub also failed, which certainly added to the confusion. This time though, when I pulled the hub, it was pretty clear the bushing itself failed (obvious signs of slippage). Now I still need to investigate the water passage aspect (was rubber overheating? If so, I still have a problem.), but in the mean time I've installed a new prop (details below) that does not use a rubber bushing. I took the re-hubed prop back to the prop shop and he re-repaired it for me (no charge), so I'll keep it around as a spare.