Lower Unit/Gear Problem

[FishHunt23]

So I just got my motor running well after a number of repairs. The only thing I haven't touched is the lower unit (except changing the oil, of course). Last night I had it out and it started making a ticking/knocking-type noise. I was headed downriver and was a few miles away from the landing so I turned around. Noise got worse. I throttled back and was hoping to make it home at 1/2-2/3 throttle. No such luck. It made a "snap" noise like a gear slipped and I immediately brought it down to idle speed. I limped home at 4-5mph and it was ticking so loud that it sounded like a helicopter. I would have loved to not run it like that, but I was two miles downriver at dark with nobody around -- no choice.

So obviously one of the gears, somewhere along the line, is having problems. I didn't get home until fairly late so I didn't have time to inspect the lower unit other than to drain the case to make sure there wasn't water in there. I took the lower seal off first, and it was very pressurized. The screw shot out when I got it loose. I removed the top screw and drained the rest of the oil.

There was no water in the oil. There was a LOT of metal. So much that the oil was silver and the magnet on the lower seal screw was totally full. Obviously, I've got a problem. What I'm wondering is what I should look for. I imagine I'll drop the lower unit and find a big mess somewhere in there. I'm hoping I can avoid replacing the entire lower unit, obviously, but I might not have a choice. Any advice or pointers before I dive into this thing? By way of background, the last time the lower unit was apart at all I had a mechanic replace the water pump and inspect it when he rebuilt the powerhead. I can't imagine he put it back together wrong, but stranger things have happened...

Thanks for any advice.

John

 

[FishHunt23]

Re: Lower Unit/Gear Problem

Almost forgot: 1988 Evinrude 70, in case that make a difference.

 

[FishHunt23]

Re: Lower Unit/Gear Problem

No advice? I'm diving in tonight. Hopefully I'll be able to just replace a couple of gears. I'm not excited about the prospects.

 

[Kevin W]

Re: Lower Unit/Gear Problem

my thoughts are this...
You got issues some major lower end issues.
It definately sounds like it has gear issues and the metal chucks most likely damaged the bearings.
The good thing is most likely the shafts and shifter dogs are still ok

without seeing it i would guess it would need seals, bearings and gears.

not a great thing it could be worse.

 

[Walker]

Re: Lower Unit/Gear Problem

Yep, every tick you heard ground off a little of the mating edges of the clutch dog and the forward gear. To do the repair job right you have to by the set and then all the tolerances in the lower unit should be brought back up to specs with the use of special tool and shims.

 

[zzzzz]

Re: Lower Unit/Gear Problem

reverse gear part # 318304=$169.00....clutch dog # 318303=$92.59....pinion & forward #397338=$294.00...all still available

 

[FishHunt23]

Re: Lower Unit/Gear Problem

Thanks for the advice, and the part #'s especially. I'm thinking I may just try to find a salvaged lower unit since they seem to be available for $500 or less. Question: are the Johnson and Evinrude lower units interchangable for this engine? So if I found a lower unit off a 1988 Johnson 70, would it work? I'm assuming yes...

 

[FishHunt23]

Re: Lower Unit/Gear Problem

Sorry I got lazy on you guys ... I researched it and got my answer (yes). Thanks for all the help and advice!

 

[FishHunt23]

Re: Lower Unit/Gear Problem

I removed the lower unit last night. Now I have a new question.

The driveshaft (4 lugs) has some wear at the top-end connection. It doesn't look terrible, but I'm a little worried about it. I'm not honestly sure if it's damaged or not because while it looks a little worn, it doesn't look like it shouldn't work. I became more concerned when I removed the water pump because the wheel did not slide smoothly off the top of the shaft ... I had to tap it off gently with a hammer. Seems like I shouldn't have to do that.

My concern is that there is damage to the driveshaft and/or whatever it connects to up in the powerhead. I'm not a total idiot when it comes to outboards, but I only know about things I've dealt with and this isn't one of them. What does the driveshaft connect to up top? Does it connect directly to the crankshaft? Is there a diagram online I can look at? The motor had a new (salvaged) crankshaft installed last year during the rebuild. That was all done by a pro.

My ultimate question: How should I determine conclusively that the powerhead's connection to the driveshaft is solid?

Thanks a million for the help!!!