1976 Mercury 1150 - Water Problems, Several of Them

jtexnm

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After to rebuilding the fuel pump today, I was excited to finally let my 1150 run for more than a moment. It started right up and I got the pee hole working. But then I noticed water in places I don't want it and another issue.

I'm not knowledge so I don't know the parts. I noticed 4 issues or might-be-issues. This motor has good compression in all cylinders.

1. Water pooling slowly below the spark plug threads.

IMG_20221231_172929.jpg

I assumed that the water was coming through the spark plug threads but perhaps it's not. It seems like all of the spark plugs have about a drop of water below them every minute or two. Hard to see in this picture but it's water between the round black metal and the spark plug.

Q: Do I need to do something to keep the water from freezing and damaging something inside the motor? In my climate it's below freezing most of the day this time of year and tonight is the one night in months that it's going to stay above freezing. So if this is an issue it sounds like I need to address it tomorrow.

And what's the issue? Google says it's the water jacket. If that's the case does anyone know how to change it? Or have instructions?

2. Water blowing out exhaust.

IMG_20221231_173226.jpg

Not consistently but it does this. Especially when I moved the throttle up with the fast idle lever, it was spewing water out.

3. Grinding when shifting forward/reverse.

When I shifted forward, I heard a subtle single grinding noise. It did go into gear and seem to spin the prop fine.

When I shifted into reverse, I heard two more loud grinding noises. I guess that I could Google this one but I'm throwing it out here as part of my list.

4. Is water supposed to come out of this vent-type hole in both sides of the lower unit?

IMG_20221231_172919.jpg

I feel embarrassed to know so little about lower units. But this thing was putting out pretty consistent water, I saw a slight oily sheen to it. But I don't know, that might be cleaning off the two-stroke oil and gas that had run down the lower unit previously.

This motor is feeling like a lot more work than I realized. Thanks an advance for your advice.
 

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racerone

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Remove cover around sparkplugs.----Replace gasket.----Water out the exhaust is normal.-----Shift quickly.----Do not ease it into gear.----So no " granny shifting " on outboard motors !
 

jtexnm

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Remove cover around sparkplugs.----Replace gasket.----Water out the exhaust is normal.-----Shift quickly.----Do not ease it into gear.----So no " granny shifting " on outboard motors !
Thanks for the advice.

Do you know what that gasket is called?


I did shift quickly. This is the first boat I've worked on but I've owned a few before. There's resistance when it grinds that slows the shift.
 

racerone

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A new motor with warranty is a good option.-----No need to fret and get dirty hands.
 

racerone

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Repair of outboards is not that hard.---Just need a manual and some time.
 

jtexnm

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Repair of outboards is not that hard.---Just need a manual and some time.
That's what I was hoping. I've got 1 manual (offial Mercury from 70's) but it has some gaps. And I've got 3 other manuals en route (I bought all of them).

Would you say it's normal for the exhaust to spit out A LOT of water when the throttle is up? Like a hose? The motor didn't sound as good as it did at idle. I only let it run for a moment because I got concerned about the water.

Watching more videos and reading, I suspect the water around spark plugs is coming from in front/beside the plugs. Like the metal cover gasket. Folks online mentioned trying to seal the metal with silicone.

I think I'll take out the spark plugs (I did to compression test but this was before water) and see if there's water inside the tubes or on the plugs. Any other ideas?

Seems like the gasket under the cover can be replaced. It's $15. But many people mentioned the bolts breaking and the powerplant having to be lifted as a result.

As #4 is concerned, I read every page of the lower unit sections of the Mercury manual and can't figure out what that hole is or if water should be coming out. The manual only covers rebuilding the LU.
 

jtexnm

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I've picked up a few things.

2. This is the exhaust relief port. I'm still trying to figure out if a huge spray when fast idling is normal.

3. Dog clutch?

4. This is a water outlet above the anticavitation plate. It's normal. So #4 is solved.
 

Chris1956

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Water out the exhaust relief is normal. Water out the grates above the antiventilation plate is a good thing. That is where it is supposed to come out.

Water around the spark plugs happens. Dry out the area and put some silicone caulk around the spark plug and it will stop leaking. Replacing the gasket will involve removing the 1/4-20 bolts, and some of them usually break. Then you need to drill and retap 'em. Not worth it in my opinion, if the caulk solves the issue.
 

jtexnm

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Water out the exhaust relief is normal. Water out the grates above the antiventilation plate is a good thing. That is where it is supposed to come out.

Water around the spark plugs happens. Dry out the area and put some silicone caulk around the spark plug and it will stop leaking. Replacing the gasket will involve removing the 1/4-20 bolts, and some of them usually break. Then you need to drill and retap 'em. Not worth it in my opinion, if the caulk solves the issue.

Thanks Chris. That's reassuring about the exhaust.

For the gasket, I guess I'm gonna caulk it. Tapping the holes and lifting the powerplant sounds like too much work for a small issue. I was thinking the water was coming out of the threads! What a relief.
 

merc850

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The bolts on the water jacket cover go thru the 2 pieces and have a nut on them; even if they break you can replace them with stainless.
Don't rev it past 2,500rpm in neutral!
 

jtexnm

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The bolts on the water jacket cover go thru the 2 pieces and have a nut on them; even if they break you can replace them with stainless.
Don't rev it past 2,500rpm in neutral!
I didn't know that about the RPMs.
 

merc850

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There is a jacket that is cooled to keep the exhaust from burning it up. Fig. 26. I noticed a white thing in one picture is water coming out of it?
850-exhaust-cover.jpg
 

jtexnm

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Dec 24, 2022
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There is a jacket that is cooled to keep the exhaust from burning it up. Fig. 26. I noticed a white thing in one picture is water coming out of it?
View attachment 374062
It looks like it's coming out from that cover near the rightmost bolt marked 6.

I'm guessing this is the kind of thing that I should fix but isn't critically urgent.
 

racerone

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Some will argue.----If the leak got worse ,then the risk is water getting inside the motor via carburetors.-----That could reduce the motor to scrap.----So you need to repair that now , if not sooner.
 
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