possible cracked block? (Mercruiser)

[b0mbtrack]

Mercruiser inboard. V-8 carbed. thunderbolt iv or v. freshwater cooled. Not sure about years or numbers....

I went to start it for the first time this season and it wouldn't turn. Pulled some plugs and had some anti-freeze come out, mainly out of the rear plugs and the ones under the risers. I checked the anti-freeze with my checker and it says it is good. I did that in the fall too so I'm kinda ruling out a cracked block but am still nervous.

As far as winterizing, i did my usual. Check anti-freeze, drain saltwater side and run with anti-freeze, fog cylinders.

Risers were done 2 years ago, i'm not sure when the manifolds were done last.

I'm just looking for some clue on how I should go about checking how the anti-freeze is getting there.

 

[180shabah]

Re: possible cracked block? (Mercruiser)

Preasure is the coolling system and listen for the leak.

 

[b0mbtrack]

Re: possible cracked block? (Mercruiser)

Ok, update.

I pressurized the cooling system with the pump at the heat exchanger at 15psi. I didn't notice the pressure dropping so i spun the engine over by hand and it still didn't go down. (I did it by hand because the starter broke the first time it tried to crank and wouldn't.)

I then left it alone for 15 minutes and came back to see the guage had dropped from 15 psi to 13.5 psi. Doesn't seem like much to me.

I can't find my stethoscope but when I do I'll do a better check to see if I can hear anything. What do you guys think about such a small drop in psi?

 

[180shabah]

Re: possible cracked block? (Mercruiser)

What do you guys think about such a small drop in psi?

I think it is still a leak, and it will get worse, not better.

 

[Bt Doctur]

Re: possible cracked block? (Mercruiser)

How did you winterize it, step by step?
You mention checking the A/F and draining the seawater side?
In this order:
You flushed the motor
you fogged the motor
You drained the block and manifolds
You poured the A/F into the block and the manifolds
??????????????????????????????????????????????

 

[b0mbtrack]

Re: possible cracked block? (Mercruiser)

Here is my winterizing steps....
The first thing I do is check the anti-freeze to make sure it won't freeze, I believe it was at -20 or -30.
Then I'll drain the saltwater side of the cooling system.
I then hook up the saltwater side of the cooling system with the non-toxic anti-freeze in a bucket.
I then run the engine and fog the cylinders by putting the marvel mystery oil in the carb.
I stop when I see the anti-freeze coming out the back along with a lot of fog.
Thats all I do really, what do you think?

Should I do a cylinder leak down test too?

I let the pressure guage sit for about another hour and it dropped to 10psi.