FUBAR lower unit? 70hp Evinrude

[SoggyBritches]

I just picked up a 1987 lund with a Evinrude 70hp 70873c on it.

The story goes like this.

He was on the ohio. Trolling, fishing a hole.
Decided to leave the hole.
Fired up the 'rude and it wouldnt go anywhere. Dragging.

So his idea to fix it......... can you guess............ FULL THROTTLE!!

So he guns the throttle and not only did that NOT fix the problem (of the tree limb that was in the prop) but he said a
banging sound came from the lower unit.

So now, as it sits in my driveway, I am curious as to how much damage has been done.

I know ZERO about boats and outboards. Otherwise I would start it up and see what kind of noise's are coming from where. But im sure I may do more damage.

With a manual, I have no problems fixing anything.

My question. Is there simply a key or pin that shears in the event of over torque on the prop drive? :facepalm: What am I saying. I should know my luck. Its prolly a pile of sheared gears, elbow deep, and upside down...... made from Unobtainium.

 

[Larry3215]

Re: FUBAR lower unit? 70hp Evinrude

Tis the season of good cheer! Think positive - some times you get lucky.

There is a shear pin behind the prop nut. Pull the prop and see if you got lucky.

 

[durban]

Re: FUBAR lower unit? 70hp Evinrude

i dont understand what a lund is what ever it is ? 70873c means 1978 to me , strip your gearbox down & examine the dog gear its got a pin going through the sharft . cheers

 

[Faztbullet]

Re: FUBAR lower unit? 70hp Evinrude

There is a shear pin behind the prop nut. Pull the prop and see if you got lucky.

Sorry but no pins on this model.....

strip your gearbox down & examine the dog gear its got a pin going through the sharft . cheers

Sorry but no as all this pin is for is to slip clutch dog forward/neutral or reverse, as dog is splined on the prop shaft and has no load applied on it.
First... check the gear oil and see if its full of metal particles. If it looks good (no metal) pull prop and inspect hub as it may be spun. If that look ok, start engine and see if you have shifting while running and water pump works, if no shifting or pump driveshaft broke above water pump. If it pumps but no gears driveshaft broke at pinion.

 

[Home Cookin']

Re: FUBAR lower unit? 70hp Evinrude

agreed; there's a whole lot to look at before tearing up the lower unit (LU).

unless it's in the water now, start it on muffs and carefully go through the gears at low speed. No problems? then launch it and run it. If the prop slips, it's spun and get it reworked. easy fix.
If you have problems shifting on muffs, then you may have busted some gears in the LU. If nothing is happening it could be the gears or the rare event of a broken/bent drive or prop shaft. If it's funky, then gears. the metal filing test is a good start (most motors have a magnetic screw for the bottom drain).
I personally wouldn't rebuild a LU that old. If you can't find a parts motor at the boat junk yard time to repower. i understand setting the parts in a LU is difficult.
I assume you didn't pay anything for the motor in the first place.

 

[steelespike]

Re: FUBAR lower unit? 70hp Evinrude

With a little luck the banging could have just been the clutch dog slipping.
As suggested check the oil for debris put it in the water and gently test forward and reverse. Shift crisply.Not jamming it into gear nor dragging it too slowly,gradually accelerating to max rpm.
Banging could also have been the blades striking the object.
If the prop was jammed against something applying power should have caused the prop hub to slip.
If the motor revs like it loses its grip now it could be the hub slipping.

 

[bonz_d]

Re: FUBAR lower unit? 70hp Evinrude

I personally wouldn't rebuild a LU that old. If you can't find a parts motor at the boat junk yard time to repower. i understand setting the parts in a LU is difficult. .

Also agree. Just received the manual for my 1975 50hp and from reading through it that is something that I wouldn't want to tackle. There also seems to be a couple of specialty tools needed to do it correctly.

 

[bob johnson]

Re: FUBAR lower unit? 70hp Evinrude

from the description we know very little...but apprently the boat motored back to the ramp!!

one check would be to spin the prop while in nuetral( what it probably is right now) then shift into forward or reverse and see if the prop turns....might have to turn the prop while shifting...it should lock, with the expection of some back lash.

other than that, you should just put the boat on muffs or in the water and run.....and shift it into gear forward and reverse, see what you hear

good luck

bob

 

[SoggyBritches]

Re: FUBAR lower unit? 70hp Evinrude

Im sorry. I forgot to mention, he had a 5hp kicker that he used to get back with.

I dont know if the 70 lost all thrust, or just didnt have enough to beat the river current. Im gonna try to extract a better story from him today. :deadhorse:

 

[Home Cookin']

Re: FUBAR lower unit? 70hp Evinrude

one check would be to spin the prop while in nuetral( what it probably is right now) then shift into forward or reverse and see if the prop turns....might have to turn the prop while shifting...it should lock, with the expection of some back lash.

That's what I would have done first but I didn't want to say it out loud; there was a detailed discussion once about how terrible it is to shift an OB that isn't running. Somehow I've been lucky all my life. I also rev it in neutral and haven't had a run-away. The Lord looks out for fools and drunkards.

 

[boobie]

Re: FUBAR lower unit? 70hp Evinrude

With all the good comments above, give us a report back when you find out something.

 

[SoggyBritches]

Re: FUBAR lower unit? 70hp Evinrude

Ok. I asked for clarification on the story.

They were cruisin about 'medium speed' on the ohio. They were in the front of the boat.
They heard a 'bump' noise from the outboard. Then the engine rpms climbed slightly (as if it were in neutral).
So they throttled down to inspect.
They thought they hit a log, but could find no evidence of one. So they hit the throttle a few more times, but still very little thrust.

So they just shut it down and used the 5hp kicker to get home.


So, apparently something in the drive failed spontaneously. :noidea:


I went out and drained the oil. It looked like charcoal gray metallic paint. And 2 nice chunks of steel were stuck to the magnet of the drain plug. :facepalm:

Santa came early this year. :frusty:

Now if I can find a manual, im gonna take it apart today and I'll post some pics for you all.

 

[SoggyBritches]

Re: FUBAR lower unit? 70hp Evinrude

I have taken 6 bolts out of the lower unit, and it still wont drop. ? Any thoughts?

Any where to download a manual?

 

[oldcatamount]

Re: FUBAR lower unit? 70hp Evinrude

Go to marineengine.com. You can look up your motor there and it will show you a parts breakdown. It looks like there is a seventh bolt (larger one) coming up from under the cavitation plate (maybe underneath the anode).

 

[SoggyBritches]

Re: FUBAR lower unit? 70hp Evinrude

Yup. Just got it. Thanks. Now we are stuck on the shift lever. Gotta figure out how to get it loose.

One thing worth noting. We put it in gear, and turned the prop and it turns the motor. So there isnt a complete loss of drive contact. But there was some nasty noises.

 

[oldcatamount]

Re: FUBAR lower unit? 70hp Evinrude

Soggy, you may have to remove the bottom carb so you can get at the shift rod connection (guessing here so take a look first). When you do get the lower unit off, measure the height of the shift rod before you remove it from the gear case. You'll need to know that when re-installing.

 

[SoggyBritches]

Re: FUBAR lower unit? 70hp Evinrude

Already got it. Thanks.

I will make sure to measure the rod. Great info! Thanks

 

[Home Cookin']

Re: FUBAR lower unit? 70hp Evinrude

sounds more like a spun prop to me--I would have checked that first

 

[SoggyBritches]

Re: FUBAR lower unit? 70hp Evinrude

Not sure if spun prop is all it is. With the metal chunks coming out with the gear oil, Im assuming a complete tare down is in order?

I will disassemble prop side first, unless god says no.

 

[boobie]

Re: FUBAR lower unit? 70hp Evinrude

If you had chunks and not just fine metal shaveings I'd say a tear down is in order.