1989 Yamaha 115hp Two stroke - lower unit

Edgewater37

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My outboard engine repair expertise are nil.

Dad and I took the boat out on the river after having sat for 3-4 months. Tested everything before we left the house, idled fine, started right up, revved up just fine. He had the engine serviced after last time it was used.

In the water in the no wake zone, idled fine about 5 mph, dont have a tach so I dont know what rpm. When we tried to gun it out of the hole, it just died. Over and over. We had to limp back, it wouldn't go over 5-7 mph back and stalled out frequently.

I'm not 100% on this, but when we got back to the house, this evening I was looking the lower unit over. Found two problems.

1) wasp nest in what I THINK is the exhaust port above the prop.

2) a small hole below the fill plug for lower unit oil that was leaking a small stream of milky water contaminated oil out of it. (I found a crack in the lower unit by the prop that is probably the source of that.

My question's are

a) is this the exhaust port, if it is, would this wasp nest cause it not to accelerate under load, in the water, vs. on the trailer out of the water?

b) can a lower unit be repaid with a couple inch corroded crack, or repaired some other way?

c) where would these leaks be coming from to contaminate the oil, a prop shaft seal, or something else?

Edit: I removed the prop and the crack revealed the inner surface was an area where there is water inside anyway, so the crack is just a crack, I don't think its critical of operation. I also got a hook tool and pulled the wasp nest out. It was about 3" across and 1 1/2" thick.. on the upper area of what the picture shows. It was a lot of material.



Pics attached
 

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99yam40

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did you drain the lower unit to see what was inside?
if water gets in it can let oil out.
drop lower unit and Pressure check lower unit to see where it leaks if you find water inside


my bet is on carb/fuel issues not exhaust
 
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Edgewater37

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did you drain the lower unit to see what was inside?
if water gets in it can let oil out.
drop lower unit and Pressure check lower unit to see where it leaks if you find water inside


my bet is on carb/fuel issues not exhaust

So what is the purpose of that hole there on the pic? it looks like a drain hole but I can't imagine what for really..
 

robert graham

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Remove lower unit, remove prop, drain oil from lower unit, wire brush area of crack to determine if welding/repair is an option....it looks to me that welding may be a possible solution....if so, then after welding you may pressure test/check lower unit for any leaking seals in need of replacement. While lower unit is off would be a good time to replace the water pump and replace any seals....If that crack is caused by corrosion of bearing carrier threads then you may need the help of a qualified Yamaha technician for removal/replacement of the carrier...
 

robert graham

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And the carbs are probably needing removal, disassembly, rebuilding....another good job for Yamaha Technician...
 

99yam40

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that hole is a water drain for the midsection
water that leaks out of water pump at the drive shaft has to drain out so they put holes in to let it out
 

Edgewater37

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that hole is a water drain for the midsection
water that leaks out of water pump at the drive shaft has to drain out so they put holes in to let it out


Ok so the grey goo that flows from it is just the leavings from combustion/exhaust and whatnot.. thanks..

I'm thinking the carb job and seals will be a bit much for me to tackle - will take it to the certified yamaha tech tomorrow and see what they say. Not looking forward to the price tag but it is what it is..
 

robert graham

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Yep, and the Yamaha guy may have a preferred welder for your cracks.....if price of repair gets too high maybe check on availability/price of good used or rebuilt lower unit....
 

Edgewater37

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Yep, and the Yamaha guy may have a preferred welder for your cracks.....if price of repair gets too high maybe check on availability/price of good used or rebuilt lower unit....


I've done some looking, not a lot of 115ETLF lower units out there.. I'm not 100% on the compatibility of the other model years with the rest of the unit though.
 

robert graham

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Some other HP/models lower units can be interchangeable with yours...do some calling/research. Hopefully a boat dealer may know of a motor with a blown powerhead and wanting to sell the parts....
 

Edgewater37

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Well I got a repair estimate back from the reputable 5 star Yamaha shop here in Central Florida.. This is the deal:

They broke two bolts getting the lower unit off, had to tap them plus diagnosis: 290.00
Clean both dirty carbs @ 300.00, if kits needed up to 600.00
Lower unit needs driveshaft seals
Lower unit needs full water pump replacement

Full total repair bill with labor will be 1900.00

I told them to put it back together, I'll be picking it up tomorrow afternoon. Already 300.00 in the hole.

Dad says to sell it.

I say, if I can pull my transmission out of my 4runner truck and replace a rear main seal and freeze plugs, plus a clutch, I can do seals on a lower unit and clean some carbs. I've just never done much marine engine work at all. I think with the right resources I can probably do it, for a hell of a lot cheaper.
 

Edgewater37

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Well.. I got the carbs off, two nuts were rusted to the lower studs on the bottom carb, had to spin the studs out and soak them in pb blaster to get the crud off. Got the lower unit off as well. Now to clean the carbs best I can and order some parts.

About carbs. I've never done them before. When you unscrew jets and stuff, should I be counting the turns out, and re-assembling with the same amount of turns, to keep everything the same as originally set? Any suggestions to make things easier? I'm terrified of getting them all out of whack..
 

99yam40

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Get a Yamaha service manual and set the pilot screws to the settings they list for your motor after cleaning.
Never hurts to count turns out from lightly seated where they are set before taking apart though.
Follow the link and sync procedure in manual every time after reinstalling carbs
 
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Edgewater37

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So I've got the lower unit off, trying to get the driveshaft oil seals out. The bearing housing is really suck onto the base. Got the 4 bolts out, can't for the life of me get the housing loose though. I've tried tapping/hammering all corners for about an hour to try to loosen it up, to no avail. Tried prying it up with a massive flathead screwdriver and it just won't break loose. Any suggestions? The oil seals are so rotten that removing them with the drill/screw method just tore them into pieces. I'd like to get the housing out so I could do a real proper removal of the stuck/rotten seals..
 
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