Merc 888 popping frost plugs

[97fordrunner]

Hi all, let me give you the back story on this problem. I had a buddy show me how to drain the block and manifolds on this last fall to winterize it. Long story short I didn't get RV anti freeze in it in time and a the frost plugs on the right side of the block popped out . When I saw that I was sick to my stomach as I am normally on top of things like this. Anyways I put new frost plugs in and ran it extensively in the barrel and had no problems even testing thru the rpm range. Now I put it on the lake and when putting along its fine but the second I go wide open to jump up on plane it pops the one right by the starter. I don't think there would have been enough water in the block to Crack the block or if so high enough to be a spot to allow compression in. I'm thinking I just am not getting it driven in square with the starter right there but I don't get why there would be so much more psi in the system to pop it when it was fine in the barrel. Would the water system act different under load then with out a prop?. I'm confused as all get out with this. Shouldn't be head gaskets. Oil level is perfect and plugs look good as well. Temps are great.

 

[flipbro]

get a new core plug! Put some loctite on it and pound it in. Brass

 

[97fordrunner]

Loctite or red silicon? I used red silicon so far

 

[flipbro]

Try the blue loctite. just a suggestion. I really cant see why it keeps popping out. Are you pounding it in flush with the block? I install them 1/8 inch counter sunk. Dont try to use a used on get new.

 

[achris]

Brass core plugs are supplied with the lip slayed out slightly. As they are installed that lip is compressed and holds in on the block. Once it is popped out it no longer has that slayed lip. You need to buy a new plug, remove the starter motor and install the plug properly, square and fully driven in.

Chris......

 

[97fordrunner]

Roger that, got a bunch ordered