Questions about a 77 115hp

[sasanm]

Guys,

A friend of mine wants to sell me his 1977 115hp Tower of Power inline 6 mercury. The price is cheap $400 (including the steering system which I need for the boat I am restoring) but there are several issues. First last year he said that several times he would punch the gas to pull a skier the motor would die out. He thinks it might need new points and cap somebody else told him that most likely the carb needs cleaning. I was wondering what you guys think? Also we ran a compression test and we found cylinders 1,2,3,5,6 had a compression of 140 and cylinder 4 had a compression of 70. What do you think is causing this? Also any ideas on how much to fix? Also do I need to fix it since I will be using this on a 19 foot aluminum fishing boat and not pulling skiers only going from spot to spot?

Thanks,

James

 

[gregpro50]

Re: Questions about a 77 115hp

Sounds like she needs a rebuild. You will never get it running good with a compression reading that low on one cyl. Try putting some oil in that cyl and then do the compression test again. If the reading comes up then its worn rings and/or a scored cyl.

 

[Chris1956]

Re: Questions about a 77 115hp

OK, The hesitation is likely dirty or misadjusted carbs. The rotor is not removeable from the shaft. Replacement of the rotor shaft is $200+ labor. Replacemnt of the dissy cap is $100+. The labor is easy.

The low compression in #4 is a concern. Pull off the middle transfer cover and look the piston, rings and cylinder walls over. If they are scratched up, a rebuild is in order. Pistons are $100, boring is $50 plus gaskets $50, plus the labor ($1000 or so). If the ring are just stuck, perhaps a decarbonization treatment will fix it.

That is an old motor. The price is OK, if it was only used in fresh water, and the #4 cylinder responds to the decarbonization.

 

[sasanm]

Re: Questions about a 77 115hp

I plan on tearing it apart over the winter. Do you guys think I will make it worse if I run it this way for the summer?

 

[Kev144]

Re: Questions about a 77 115hp

yes it will make it worse