head gasket on 75 15hp opinions needed

OLDIRON

Petty Officer 2nd Class
Joined
Apr 2, 2008
Messages
135
I was given a 15r75c.I have no history of this motor.I have replaced the impeller,spark plug coils(because they were rusted an the laminations were swollen),spark plugs,and with the help of another forum member,rebuilt the carb.She runs great now.I also drained the gearcase,and found old brown oil.Nothing that would indicate any water intrusion.Compression is 90+lbs.My question to you is, should I attempt to change the head gasket?Or should I let sleeping dogs lay? I want it to be reliable,but I have heard here,that if a motor has been in salt water,getting head bolts off in one piece is iffy.I donot know if this motor has been in salt water.I did find some minor white stuff under the pump housing,which cleaned up easily.The only indication of rust was the spark coils.The head bolts are still painted green,and look to me like they have never been removed.To change or not to change...that is the question.Thank you.P.S. I have bought a original OMC repair manual for this motor,but it won't be here for atleast a week.
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: head gasket on 75 15hp opinions needed

Personally I would say leave it for now. That is just my own humble opinion though. Your maintainence so far is good. Just use your compression readings as a benchmark and keep an eye on it. Sounds like this motor will treat you as good as you have treated it for a long time. Happy boating.
 

wbeaton

Commander
Joined
Jul 30, 2006
Messages
2,332
Re: head gasket on 75 15hp opinions needed

Why bother if it runs fine? Changing the head gasket isn't going to bring compression up to 120 psi or anything. You could do a decarb and that might help a little. I'd just enjoy it.
 

jethro66

Petty Officer 2nd Class
Joined
Jun 29, 2006
Messages
151
Re: head gasket on 75 15hp opinions needed

Try doing a decarb first.Maybe there's a lot of crud in there.See if you can get comp. up to 100.There's a good tutorial in the faq.
 

OLDIRON

Petty Officer 2nd Class
Joined
Apr 2, 2008
Messages
135
Re: head gasket on 75 15hp opinions needed

Thanks all,I think I will just leave it be for now.She starts cold on the third or fourth pull ,and on the first pull after she warms up.I know I shouldn't compair it to my little Merc/Tohatsu,which pretty much starts like on the first pull cold.I can't compair a 96 motor to a 33 year old motor.But this Johnson will probibly outlast my Merc.It's built like a tank.I like it alot! Thanks again eveyone.If it ain't broke,don't mess with it I guess is the guideline here.
 
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