Freeze Plug

Jan 22, 2008
402
Catalina 380 16 Rochester NY
A not so uncommon woe....

Got caught in Upstate NY by the cold weather before I could winterize boat.
In a panic, I tried to do it a few weeks ago when I was in town, but the bilge was frozen solid (I still cannot figure out where the water is coming from!!!!)

I have a tee that allows me to pull antifreeze from a bucket and has worked great for the past 8 years. I got the motor to start, but it wouldn't stay running. I finally gave up and when I went back down below, I could hear bubbling and hissing.

I popped the aft freeze plug of the Atomic 5 gas engine near the distributor.

I ordered new plugs from Moyer and today I went down and ran a propane heater for 3 or 4 hours to melt all the ice. I was able to remove most of the water from the bilge and I cleaned out the opening for the freeze plug...installed some silicone and was able to put the plug into place, no problems.

Once I started the engine, the freeze plug immediately popped out and the engine just squirted antifreeze all over the place. I stopped the engine and cut down a wooden plug and hammered in into the hole so that I could at lease get some liquid in there for the rest of the winter.

Obviously, I didn't install plug correctly. As I was driving home, it occurred to me that the plug/cap is concave in shape. Do I need to place the plug into the hole and then somehow bang the dome shaped cap 'down'?

I tried looking on this site and Moyer's and didn't quite see anything....or I missed it.

Thanks guys.
Chris

...as an aside. I noticed in the bilge that water froze around the keel bolts in a clear dome pattern...I thought this was weird and kinda cool from a freak of nature point of view. Is this normal?
 
Jul 1, 2010
962
Catalina 350 Lake Huron
Not familiar with the freeze plugs on your engine, but in my previous life I installed quite a few on car engines. The concave side faces out. We never put silicone sealer on a freeze plug. If we used anything, it would have been Permatex gasket cement. Not sure if they make one for your engine, but in a pinch there are aftermarket ones that consist of a rubber plug with a center screw and bolt that cause it to expand in place when you tighten it.
 
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Sep 14, 2014
1,251
Catalina 22 Pensacola, Florida
Yep concave side out, and it is a press fit, actually had one on top of block on a outboard engine, got rusty and leaked water when engine was running / got replacement from marine dealer who did not believe me when I asked for one. Made both of us a believer.
 
Jun 2, 2011
347
Hunter H33 Port Credit Harbour, ON.
If the plug is flat and dish shaped, without a lip on the sealing edge, it is normally installed convex side out, concave towards the engine. When the plug is in place, tight against the stop machined in the block, take a flat punch, about half the diameter of the plug, and strike the center of the plug. The idea is to drive the convex side in towards the engine. Since the outer edge is stopped by the block the plug will expand in diameter locking it in place. Be careful not to over strike the plug as it will loosen off. It should only take 1 good strike on the large diameter punch to set it correctly.

Good luck. Engines don't like hard water.
 
Jul 1, 2010
962
Catalina 350 Lake Huron
If the plug is flat and dish shaped, without a lip on the sealing edge, it is normally installed convex side out, concave towards the engine. When the plug is in place, tight against the stop machined in the block, take a flat punch, about half the diameter of the plug, and strike the center of the plug. The idea is to drive the convex side in towards the engine. Since the outer edge is stopped by the block the plug will expand in diameter locking it in place. Be careful not to over strike the plug as it will loosen off. It should only take 1 good strike on the large diameter punch to set it correctly.

Good luck. Engines don't like hard water.
Yes. I was thinking of the cup type plugs in my post above.
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Jake has it on this one, I think.. A picture of the Atomic 4 shows the exhaust manifold "freeze plugs" as being convex side out with a distinctive punch mark in the middle to expand the sealing edges.. Most engines have the concave side out, so the confusion.. The lip or stop in the hole that the plug goes into is the determinant.. if a lip, convex out.. if no lip, concave out.. The Yanmars and Kubotas that I have played with all have concave out..
 
Sep 14, 2014
1,251
Catalina 22 Pensacola, Florida
OOPs my bad , i meant the concave side it towards you when fitted, no lip, press fit and should be tight when done. Real bitch to remove until perforated so you can get a grip on it as it is designed to fit flush.