72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of engi

o2cool

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Mar 11, 2009
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Hi im working on ones of these nightmares of an engine. Its been setting for a while so i flushed the fuel lines and carbs out with a can of carb cleaner. These engines are tough cold starters but i finally got it running with spraying some mixed gas manually into the carbs. It sounded fine on a short quick rev as well as idled and restarted like a champ when warmed up... So i went out and got me a set of those water house ear muffs and put on the lower end. No water came out of the exhaust so i figured i got scammed and just took it to the lake to dunk her completely under. After we finally got the boat to cold start at the dock we took off and everything sounded fine with the engine and soon as it started to plane out the engine just weakened and got worse and worse until we were bairly trolling at wide open. We shut it off immediately cause it looked hot and there was NO water coming out of the back of the engine. SO i assume the water pump needs changing, but im wondering if i did enough damage to the motor to justify fixing the pump. Or if the engine problem will be fixed witha new water pump. Ive worked on chainsaws for years so this should be no problem for me as far as mechanic ability. I also noticed that when i drained the lower end oil it looked like a vanilla milk shake with water in it. I know this cant be good. Are there some seals or something leaking?

How much does a rebuild engine kit costs for one of these?
Will the water pump fix the performance issue if the motor isnt damaged?
Should i test the cylinders for compression before i blow more money on this and it end up being an engine problem?


I been looking for some places for advice and this seems to be a good place to learn alot. Any ideas would grealy be appreciated.
 

Laddies

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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

Overheating probably did not do much damage to the engine, however running it lean could have cooked it. Squirting carb cleaner in the throat of the carbs does not clean it. The first thing you need to do is get it running to see if it's worth repairs and it probably is but one thing a Mercury outboard will not tolerate is half assed repairs.
 

Moody Blue

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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

Chances are you wrecked whatever was left of the old waterpump impeller by running the motor dry. Running for even 10-15 seconds can cook the impeller.

I would do a compression test and see what that indicates before spending any money on repairs.

As for the milkshake LU lube, that does indicate water intrusion from somewhere. Could come from any number of places; vent or fill screw gaskets, prop shaft seal, lower waterpump seal, shift shaft seal. Only way to know for sure, other than systematically replacing parts, is to perform a pressure and vacuum test on the LU.
 

o2cool

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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

I didnt squirt it in the carb, i squirted it a hole on the side of the carb with the drain plugs out.
 

o2cool

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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

She still runs, i fired it up today but it took forever to get it to hit, is it me or are these the worse cold natured motors ever? Any tips on getting it to fire good without running the battery down? It seems to be a fuel problem, if i tap it with some mixed gas with a spray can it will pit and putter until it finally gets a lil warmed up. Altho it seems to miss when u get it under load.
 
Joined
Feb 21, 2009
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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

Well to be honest you don't deserve to have one of these awesome boat motors. Do you have any common sense at all.
 

Plainsman

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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

Get the serial # and KNOW what year it is.
Get a manual first, then do a compression test on all 6 cylinders. They should be within 10% of each other. IF that comes out ok, Get carb kits and take the carbs off and soak them in a gallon of carb cleaner. Blow them out with compressed air. While they are soaking, get a new water pump kit and fix the LU. Get a fuel pump kit and rebuild that too.
 

Nickledimed

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Feb 16, 2009
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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

As for the hard starting at cold, make sure your cold cranking amps on the battery at at least 725....as someone pointed out to me here on these forums.
these are a great bunch of ppl and they know their stuff.
 

bullbat

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Mar 10, 2009
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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

Sounds like you need to do some serious carb work and and make sure your choke is working, just went through this my self on a 1977 1150 merc that had been sittin for about years
 

dfest7

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Mar 16, 2010
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Re: 72-77 Mercury 1150 115hp Engine Performance Problems and no water out of back of

Alright, for starting this motors, they are kinda tricky. The best way that I have found is 1, make sure that the motor is fully tilted down, (they do not like to be tilted up) 2, get ready to give it some gas (keep in neutral and rev it) 3, make sure it is fully primed (these motors seem to have some weaker fuel pumps, 4. Whenever you are cold starting it, push choke all the way in while you start it (push key in to choke) do this once, maybe twice, and she should start like a beauty.

Impeller could probably use replacing, but before doing anything else, check your fuel lines, fuel tank, anything with fuel, it sounds like your motor just is lacking the fuel to get it moving. but get water moving through it first. it is not worth fixing everything else if you dont. if it will just overheat again
 
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