BIG problem! Please help

At the end of last season, I was removing the water drain plugs from my Mercruiser, I/O 4.3 liter engine block. The ones that are on either side of the under side of the block. One came out and the threads are rusted and in bad shape. I may be able to put a screw plug back into it though. The other one snapped off leaving half of the threaded drain plug in the hole. I have tried a screw extrator with no success because it is so corroded and frozen into the hole. The space is so tight that I can't get into it with a drill to drill it out and not ruin the threads, if there are even any threads left.
My question is: Are there any type of plugs that you do not have to screw into these holes to plug the drain? Does anyone have any suggestions. I am at a loss here and have no options left, that I know of. The engine runs great, but these two holes are a big problem. Any help would be much much appriciated!!

Thanks.

Re: BIG problem! Please help

My question is: Are there any type of plugs that you do not have to screw into these holes to plug the drain? Does anyone have any suggestions. I am at a loss here and have no options left, that I know of. The engine runs great, but these two holes are a big problem.

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Ayuh,.... Welcome Aboard,....

Ya need to get the old plug out, clean up the threads with a 1/4" pipe tap, 'n install new brass pipe plugs.....

Re: BIG problem! Please help

It may require engine removal to access the plug to drill it out correctly. Then tap the threads out just enough to clean them. You can also use gasket sealer on the threads of the new plugs and DO NOT over tighten them. They should be brass plugs, and they won't corrode in as easily.

Re: BIG problem! Please help

Don't the plugs screw into fittings that also screw into the block? If so, maybe replace the fittings and plug ???

Re: BIG problem! Please help

tpenfield said:

Don't the plugs screw into fittings that also screw into the block? If so, maybe replace the fittings and plug ???

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Not always. Just pipe plugs until newer models. Have no idea what hear they started that.

Re: BIG problem! Please help

Before you pull motor, go to home depot and they have a small right angle attachment that goes into a normal drill or impact. That may be small enough to squeeze under there to drill your hole out.

Best of luck