1978 140 Mercruiser stern drive

[cooders71]

I have a 1978 140 hp that I think blew a head gasket(water in the oil).I changed the head gasket,intake gasket thermostat and gasket,and the exhaust tower(riser)gasket.I did nothing to the timing,the carb,the points,nothing else and now I have a VERY odd problem.I can get it to run on 3 cyl but not 4.It starts and idles a bit rough,but does idle,with the number 4 sparkplug out.As soon as I put the plug back in<when running>,it dies right away.Also there apears to be water coming into the number 4 cyl.I need to know if there is a freeze out plug that may have went bad or what.I am beating myself up over this.HELP!!!

 

[gshldon]

Re: 1978 140 Mercruiser stern drive

It almost sounds like you might have a cracked block in the #4 cylinder. I am sure it is not what you wanted to hear but that would be my guess as i had the same problem. Good lUck

 

[APPALOOSA2]

Re: 1978 140 Mercruiser stern drive

Did you check you manifold when you had it off ? Did you have the head checked "magnafluxed" ?
Freeze plugs have nothing to do with water in a engine, just external leaks.

Did this just happen after winter storage or were you using it and it just happened. Did it overheat while using it ?

Fresh water or salt water ?