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Discussion Starter · #1 ·
I have a 1990 Yamaha 85hp. Older motor but has always ran really good. About a year ago I lost the lower unit. When I say I lost it, I mean its at the bottom somewhere in New Bern in 15' of water. Don't know what happened but that's another story. Replaced it with one I found on Craig's List. Since then I have smoke and water coming from under the motor. Only does this when in the water, does not do it on the hose. Can putt around all day 1/3 throttle with no problems, but not long after you open it up the overheat alarm sounds. He thinks it broke something in the exhaust and would have to take it almost completely apart to fix. Said it was not worth fixing. Anybody familiar with this problem? Plant Green Motor vehicle Automotive tire Automotive exterior
 

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Red X Angler
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Boat shops look at everything in labor hours. If they see it may take 10 hrs to figure out and fix an outboard they aren't going to say "fix it" because they know people don't typically agree to $1200 repairs to $500 engines. Either get a manual and learn as you go and do this yourself or find a shade tree guy like me (not really selling myself here just saying..) to look into it who will not rob you blind. Before you do anything you do a compression test on all cylinders. If compression is in the manufacturers range of good, then the engine is solid. If the engine is solid and you have a lower unit that is working properly its only a matter of figuring out what other "thing" needs to be made right. Sounds like the water inlet tube was not aligned right when the lower unit was installed, or there might be a blockage in the tube from the old damage, or bad thermostat or something related. None of which adds up to "parting it out" in my book. 85hp Yammy of any age should bring a minimum of $750 running right and $1000 is not unheard of. So whether or not to fix it really depends on who's willing to diagnose it cheaply then let you decide what to do. But smoke and water under the motor really sounds like the cooling tube isn't in place or the connecting sleeve between the lower input tube and the engine isn't aligned.
 

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Agree with Sundrop on this one. If it wasn't doing this before replacement of lower unit, then it is very likely that the water inlets or something is not lined up properly. First thing is the compression test. Then I would pull that lower unit and try to see if anything is bent or crooked, blocked, etc. Never know what you may run into with used parts, but always check the easy things first!
 

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Discussion Starter · #5 ·
When I lost the lower unit, I was running full throttle. Didn't feel like I hit anything and I was in the channel in 15' of water, but you never know. Could it have damaged something else when it came off? Right after I had the lower unit changed it ran fine except for the water and smoke coming from underneath. Never ran hot. Over time it started over heating and doing it more often. Change the impeller myself a couple months ago and it didn't help. Looked and didn't see anything bent, but I'm not a mechanic. Exhaust and water come out the prop when on the hose but underneath the motor when in the water.
 

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Red X Angler
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I would be willing to look at it. I cant really see how other than the water tube anything could be damaged by losing the lower unit. Sounds like those bolts deteriorated and stripped or let go and the unit just fell. Or someone was trying to steal it and had it unbolted and got interrupted and you found out once it dropped. Lowers are high $ and get nabbed around here. We have roving "prop" thieves too that come around the docks at night and steal stainless props off boats sitting in their lifts.
 

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Discussion Starter · #7 ·
Sundrop, thanks for all your advice. The thought of someone trying to steal the lower unit did cross my mind. Not sure what I'm going to do and I still have my 14' jon boat. Thanks for offering to look at it, and if you do I will make it worth your while. May try to repower.
 

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Discussion Starter · #8 ·
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May have found the problem. Someone told me to check the seal between the water pump housing and the exhaust tube. Pulled the lower unit and low and behold there wasn't one. Ordered the part and will see what happens about Fri..
 

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Red X Angler
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Keep us posted. Sounds like the right move.
 
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Discussion Starter · #11 ·
Well, good news and bad news. After finally getting the parts this morning, I got it put back together and took it to New Bern. Started motor and no smoke or water coming from underneath anymore. Started up the Trent and overheat alarm goes off again. Tell has a good stream. Guess it's back to the drawing board.
 

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Red X Angler
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Thermostat or internal blockage or you didn't get the pipe back in place to the powerhead when you put the lower back on.
 

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Discussion Starter · #14 ·
Thermostat was removed a few years ago, but I took the cover off anyway. Got a new one ordered with a pressure valve. I do believe the pipe was lined up, but I notice in the diagram there was suppose to be an o-ring and round rubber gasket on the pipe. Got them ordered. Could this be the problem? All the parts I'm ordering are not on the engine now, just like the seal that was causing the smoke problem. After pulling the lower unit again, I hooked the hose to the water tube and tried to flush it out. Don't know if it helped. Will see what happens. Thanks for all the input.
 

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Man I really hope you get it straight. I'm going thru some VST issues with my Yam and it seriously hurts my feelings.

Just because the motor is peeing doesn't mean water is getting everywhere it should.

Try something that breaks down salt. Many opinions expressed on what's best but I think they are all about the same.

Sent from my XT1080 using Tapatalk
 

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Red X Angler
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Sounds like a blockage in the water jacket somewhere. The problem is to really clean things out and shove some wire around in them you have to take a lot apart. A chunk of the old impeller or some clay/sand can be caked in somewhere and blowing air isn't going to get it out. Are you sure its overheating? Have you checked the temp or just judging by the alarm? When it overheats can you still put your hand on the block or is it too hot to touch? Do you have digital infrared thermometer? I would use that to search for the "hot spot". Do you know if your pressure relief valve may be stuck making the water bypass the cylinder jackets? There comes a time when you have to admit it's better to move on than keep dumping money into something especially when you have to start paying for labor. Is it overheating at idle or at speed?
 

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Discussion Starter · #20 ·
Pretty sure its running hot. The alarm goes off and the pee stream is really hot. Don't have a digital infrared thermometer.
Replaced thermostat, impeller, and pressure relief valve. Runs warm at idle and runs hot at 1/2 to 3/4 throttle. I guess the only thing I didn't change is the water pump housing. I think it was changed not to long ago but not sure. Looks good though.
 
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