70hp blown head gasket on 2 - common?

I just got a 1977 70hp triple. Compression was 120/35/120, and the #2 plug might have been too clean. <br /><br />On pulling the head, found that the head gasket was blown (looks "torn") on #2, dead center on the exhaust side. It was an OMC brand gasket, not original, and the head bolts did not feel frankly loose. The motor had been used in salt (wonder how many striped bass it had to it's credit?).<br /><br />Any expert advice here? I am wondering what to do. I am a little leery of just slapping a new head gasket in there and leaving it at that. The cylinder walls, piston tops, and head look fine.<br /><br />I know cylinder #2 is the 'trouble spot' on the triples. I plan on checking the head and cylinder tops for flatness as best I can, and I may take the exhaust box apart to check it for flatness & new gaskets. <br /><br />Anyone who's seen a lot of these have advice on what else I ought to be doing here? I'll certainly clean the carbs, new water pump, etc.. If I sell the motor, I'll probably knock the WOT timing back 2 degrees. Thanks for the help!

Re: 70hp blown head gasket on 2 - common?

throw down 10 dollars, get a new head gasket and try the compression test again.<br /><br />thats the cheapest and only way to tell whats up.

Re: 70hp blown head gasket on 2 - common?

I do'nt want to hijack this post but I have a related question. An OMC Tech,whom I respect, told me that if my Johnson 70 is used in salt-water that the head should be pulled to inspect for corrosion and re-surfaced if necessary. My motor is primarily used in fresh water but it sees salt several times a year, up to two weeks at a time. I always rinse it within minutes of trailering. It is an '89 and has never had the head pulled. What do the senior members think?

Re: 70hp blown head gasket on 2 - common?

I am concerned that the head gasket may fail again.<br /><br />Lowranger, removing the head is fairly easy on those triples.

Re: 70hp blown head gasket on 2 - common?

Your engine is 27 years old and head gaskets do fail. While there is always a reason, even though you suspect this gasket was changed once before, "old age" and "salt water" are certainly suspect in this case. Use a good straight edge and check for surface flatness and corrosion. Install a new OMC gasket, torque to spec and go for it.

Re: 70hp blown head gasket on 2 - common?

After changing the head gasket and filling with 87 oct and your fav. TC-W3 oil, after warm up, go to WOT (On the lake!)for about a minute, and just turn off the key. When the boat comes to a stop, pull one plug at a time and inspect color.<br />After a few hrs of use, if there are no plug color differences (Major) re-torque head bolts.

Re: 70hp blown head gasket on 2 - common?

It is critical to retorque the head after one warm up and cool down cycle.

Re: 70hp blown head gasket on 2 - common?

ledge, I'd go with Phat's advice and install a new head gasket. Did you say #2 plug was too clean? That would indicate water present in the cylinder, probably in small amounts from the blown gasket (the suction action of the piston will "pull" cooling water into the cylinder. Look carefully for signs of oil water mixture near the piston rings. If there is alot, then pull the exhaust cover. On a 1977 this will be a patient man's job because most the bolts will be siezed. There are lots of posts that can help you with siezed bolts. Good luck!