Frost Plug Removal (This is a Good One!)

[Scott A.]

OK, this is a good one!?

Last winter while winterizing the engine on the hard, I blew one of the frost plugs out of my 1981 Yanmar 2GM (13 HP) spewing antifreeze all over. In order to ensure that the engine had enough antifreeze, I held the plug in with a long screw driver (it would not stay in on its own) while my wife cranked the engine until the water was out. Then I left the plug in place.
Over the winter, I ordered new plugs and went to replace it today. Of course, now it will not come out. I tried prying it, slight tapping on the edge but nothing. Then I tried starting the engine to blow it out again. No luck, although it did leak. I could not trust it and wanted it out. My last ditch effort was to drill a hole through it and use a self tapping SS screw to use as a gripper to pull it out. Again, no luck, although I now have a leaking plug with a hole in it.
I have since reduced my frustration. Now I am thinking I should enlarge the hole a bit at a time until until I can get a 1/4" SS Eye-bolt in there which should allow me to get good leverage to slowly pry it out.
Does anyone have any better ideas before I try this or hire a mechanic?

Thanks for any assistance

Scott

 

[Brian M H23]

use a dull chisel or a flat punch and hammer it straight in at one edge- the goal is to make it rotate, then grab it with plies.

 

[kloudie1]

Yup, Brian is right.. OR if ya can get a small 90 degree pry bar into the (now bigger) hole in the center, you can make it rotate that way; then grab it with channel locks and pull it out. After cleaning up the sealing surface on the block, a little thin coat of gasket seal on the OD when installing the new one is a good thing.

 

[Maine Sail]

Scott

Scott,

The real question is how were you winterizing that you blew out a frost plug? Did you connect a hose to it? If it is fresh water cooled the radiator cap should have popped at 14-16 pounds which is well below where a frost plug would blow out. If it is raw water cooled and you somehow pressurized the block enough to blow out a frost plug it is quite possible you now have a head gasket issue too.

Be very careful drilling into a frost lug that metal chips do not wind up in the block! Hold a vacuum next to the drill bit to minimize this. As for the plug I would hire a good mechanic at this point because if you scratch the bore for the frost plug you'll then need to polish it back up to prevent leaks.

 

[Scott A.]

Thank-you for the replies. I used a punch and slowly rotated the plug just enough to grasp it with pliers to pull it out. I then cleaned up the bore with a soft wire brush before inserting the new plug. Being unable to use a drift straight on due to the access and starter motor, I ended up using the round head of an 8" carriage bolt. It worked fine and the boat is now in the water for the season.
So far, running around the harbour and another 15 minutes of fast idle has shown that there is no leakage.
Thank-you.

Scott