1985 tower of power 115 hp

quantumman29

Petty Officer 2nd Class
Joined
Jul 15, 2004
Messages
105
hello all,
I have a few questions about my 115 mercury tower of power,its a 1985
1st of all I test ran the engine on my 1985 glasstream bass boat which is just a smidgent under 17 foot long,I left the original aluminum prop on the engine,I added 3 gallons of gas to the gas tank but i believe i added too much oil in my mixture,the tank already had 4 gallons of mixed fuel in it already,
the engine fired right up and i waited for a nice **** stream to come out,it did after a few minutes,then i planed the boat and off i went,at 5200 rpm the boat was hitting 58mph at wot, after i trimmed it up all the way it hit 5300 rpm and hit 62mph at wot, i drove about 3 miles and returned to the dock quite impressed with not only the quickness it got on plane,but the overall smothness of the ride and the speed of the boat,I decided to put on a stainless steel prop that came with the boat and after talkin to the mechanic who serviced the boat its entire life he claimed it was the right prop for that engine and he knew it cause he sold it to the owner,
well the next morning i fired the engine up and it was noticeably blowing alot more light blue smoke,i drove the boat about 3 miles at wot and it flew with the stainless steel prop on it,after returning to the dock when i tried to power up the engine it kept bogging down and stalling,it would rev up nicely in neutral but stall in gear when the engine reved,i got scared and put the aluminum prop back on,again the boat ran well for about 3 miles then began to bogg down and stall, is this due to too much oil in the fuel?
should i empty all fuel and start again with a true 50:1 mix ratio?
do i need to replace the spark plugs now?
did i screw up the engine?
was the stainless prop too heavy? ( its 3 times heavier then the aluminum)
thanks for any advice guys and look for the updated pix of the 90% completed 1985 glasstream bassboat
mike
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: 1985 tower of power 115 hp

Never mind about the physical weight of the prop, the shaft can handle it.... What revs did you make at WOT with the stainless prop on? Those engines need to be turning at 5000-5500 at WOT, or they will detonate a piston. I actually like to spin them at about 5500-5700 if I can. But that's just me, I hate rebuilding engines if it's preventable.

Too much oil in the fuel shouldn't cause your bogging problem, unless it's like 10:1... Plugs need changing? When I buy anything second hand, the very first thing I do is to go through it as if it's never been serviced. That includes all oils, filters, spark plugs if it's an internal combustion engine of the non-diesel variety.:D

The plugs you should be running are NGK BUHW... As you pull out the old plugs, examine them CLOSELY. As eyes are the window to the soul, spark plugs are the window to the engine... They can be the early warning signs to a possible engine failure. You're looking for a little covering of oily carbon (yours might be a little more oily than usual if you're using more oil in the fuel). A lot of people pull plugs, see that are nice and clean, like very clean, and think that's great... They couldn't be more wrong. :eek: Very clean plugs are a sign that water is getting into the cylinders... Quite common on the old inlines... and really not good news....

HTH

Chris.......
 

quantumman29

Petty Officer 2nd Class
Joined
Jul 15, 2004
Messages
105
Re: 1985 tower of power 115 hp

with the stainless prop the engine got up to 5500 rpm and was cruising fine at 63 mph,then it started bogging down and would not power up in gear and when i tried to power it up it just stalled,when i restarted the engine would rev up fine in neutral but stall in gear,I also believe i flooded the engine by over squeezing the bulb as there was a strong smell of gas,also i should mention that the gas in the tank was probably old at least 6 months old and i added 3 gallons to it,plus more oil,there may have been water in the fuel from condensation,i think that would bog it down as well,the combo of old fuel and water,i will change the plugs and filter and start over now.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: 1985 tower of power 115 hp

Check your water separating filter, that will show if there's any water in the fuel.... It will be in the line between the fuel tank and the engine....

Old fuel could cause the problem you have... Fresh fuel is always the best policy....

Check the spark plugs.... See how they look....

It could also be a lack of fuel... Does the problem go away if you squeeze the fuel primer gently when it happens? If so, look for air leaks in the fuel lines, or at rebuilding the fuel pump (not a hard job)....

Chris.........
 

quantumman29

Petty Officer 2nd Class
Joined
Jul 15, 2004
Messages
105
Re: 1985 tower of power 115 hp

im an idiot,i should have used fresh fuel,im sure thats the problem,i will change the filter,plugs,and clean out the gas tank and try fresh fuel.
mike
 
Top