'57 BigTwin won't go into gear

[dthrckt]

HI folks,

'57 Evinrude bigtwin runs great. When first purchased, she would occasionally jump out of forward gear. I checked the clutch dog, found worn corners, turned it around and was good to go for roughly 60 hours of operation.

I change the lower unit oil frequently (after nearly every trip). Generally, I'd find a little water (oil looks a little milky) and lost a little oil. I'm guessing an ounce of each for ~5 hours at FT.

Half way through my last outing, I started the motor in neutral but it wouldn't go into either gear. I was convinced the upper part of the shift rod had disconnected from the lower.

So, yesterday I drained the lower unit, and only about 6 or 8 ounces of oil came out, plus an ounce of water :facepalm:

The upper rod is still connected to the lower. The drive pin is intact.

After a bit of searching I found this very helpful thread. http://forums.iboats.com/showthread.php?t=387232

I'm very comfortable working on the lower unit. I'm interested in theories on finding the leak (aside from inspecting seals), and the most likely cause of the gearcase malfunction. I have some parts motors on hand.

Also, I plan to follow the instructions from that thread, but I'd like to know how big of a job pulling the powerhead is - and any typical snags ie., parts that always have to be replaced when doing this job and mistakes to avoid...

I do have a service manual.

Thanks for any and all input

 

[Chinewalker]

Re: '57 BigTwin won't go into gear

First thing I'd do is localize the issue. Does the shift rod move with the handle (watch through the "window" on the side of the leg)? If the shift handle is still moving the shift rod, then the issue is in the gearcase and the powerhead need not come off. Pull the gearcase off and go from there...

As for the oil and water issue - most of these motors have issues with the shift rod seal - an o-ring under the shift rod guide bushing. The vertical movement of the shift rod and the gunk that builds up and is then pushed through the seal makes it the most prone to premature wear and leakage.

 

[dthrckt]

Re: '57 BigTwin won't go into gear

First thing I'd do is localize the issue. Does the shift rod move with the handle (watch through the "window" on the side of the leg)? If the shift handle is still moving the shift rod, then the issue is in the gearcase and the powerhead need not come off. Pull the gearcase off and go from there...

As for the oil and water issue - most of these motors have issues with the shift rod seal - an o-ring under the shift rod guide bushing. The vertical movement of the shift rod and the gunk that builds up and is then pushed through the seal makes it the most prone to premature wear and leakage.

Yes, the upper and lower rod sections are securely connected and move with the shift handle when checked from the inspection window.

Thanks for the shift rod seal info. I didn't know that. A bad oring would be great news compared to a bad 'spaghetti' or prop shaft seal...

 

[64osby]

Re: '57 BigTwin won't go into gear

Thanks for the shift rod seal info. I didn't know that. A bad oring would be great news compared to a bad 'spaghetti' or prop shaft seal...

If your going to crack it open you might as well replace everything, I just did a 57 18hp and it's not hard.

 

[Chinewalker]

Re: '57 BigTwin won't go into gear

I concur - you gotta take the unit completely apart anyway to replace the o-ring, so you might as well do them all while you're at it. The seal kit here on i-boats is part number 18-2686.

 

[1946Zephyr]

Re: '57 BigTwin won't go into gear

Thanks for the shift rod seal info. I didn't know that. A bad oring would be great news compared to a bad 'spaghetti' or prop shaft seal...

It's actually easier to replace the spagetti seals, than the shift rod o-ring. You'll want to talk to F_R about purchasing on of his shift rod seal remover. It's a good investment, for working on the old split case lover units.

 

[dthrckt]

Re: '57 BigTwin won't go into gear

I concur - you gotta take the unit completely apart anyway to replace the o-ring, so you might as well do them all while you're at it. The seal kit here on i-boats is part number 18-2686.

Thanks for that part number!

I'm going by a dealer tomorrow that I know has the shift rod o-ring. Hopefully he has the whole kit, because I need to be on the water wednesday.

I already go the shift rod bushing and o-ring out w/ an appropriately sized steel punch. But, the gasket didn't come out, and I can't figure out how to get it out.

I can see that I definitely need to replace the drive shaft seal. I've removed the pinion gear but not the roller bearings.

Is there a special tool for that seal, or just some trick to getting it out?

Thanks for your help guys

 

[dthrckt]

Re: '57 BigTwin won't go into gear

I can see that I definitely need to replace the drive shaft seal. I've removed the pinion gear but not the roller bearings.

Is there a special tool for that seal, or just some trick to getting it out?

Thanks for your help guys

My manual (clymer) says to remove the drive shaft seal with a suitable mandrel. Could anyone be more specific?

 

[dthrckt]

Re: '57 BigTwin won't go into gear

My manual (clymer) says to remove the drive shaft seal with a suitable mandrel. Could anyone be more specific?

found instructions in another thread. basically, pry it out w/ a (generic) seal remover and screwdriver, while protecting the edge of the housing that acts as the fulcrum w/ sheet metal.

I used a socket/mallet to seat the new one, and to drive out/seat the prop shaft seal.

I got the rest of the lower unit seal kit (except the spaghetti seal) locally, at a bit of a premium. They fit so much tighter

I guess I'll swap the spaghetti seal after my trip this week