Lost a freeze plug.

Hey guys,
water tested the boat yesterday and i'm pretty certain its the freeze plug on the back of the motor inside the bell housing. so i was just wondering if it would be worth the money saved to pull it myself and drive in a new plug. i know quite a bit about motors and cars but this will by far be the most into marine mechanics i've gotten myself into.
thanks guys,
Cody

Not a big deal.It will be the same as any gm vortec engine except the plug will have a certain amount of brass in it.I would get a plug made for marine service

Man I feel for you. One of mine fell out last year while I Was in the middle of the lake. It was underneath a motor mount, but luckily we were able to wedge my old plug back in with a pry bar while out on the water. It held all season.

If you've pulled a motor before and you got the lift you should have no problems.

How the heck does a freeze plug fall out? And why is engine damage in the cold such a problem if engines have freeze plugs?

A true freeze plug is an expansion plug located in the side of an engine block that is supposed to protect the block against freeze damage. Water expands when it turns to ice, and if the coolant does not have enough antifreeze protection it can freeze and crack the engine block. The freeze plugs (there are usually several) are supposed to pop out under such conditions to relieve the pressure on the block.

Most of the plugs to be found on an engine are actually to plug the holes where sand cores have been held. The sand cores are used in the casting process to form internal cavities in the engine block or cylinder head, for cooling water for example, and so should really be referred to as core plugs.

scooter is correct, freeze plugs are not designed to protect from freezing, they are holes in the casting from the sand cores or for machining purposes. I've seen several engines that froze and busted without the "freeze plugs" moving. I don't remember ever seeing a "freeze plug" saving an engine from damage.

Freeze plugs DONT just fall out! You better inspect the engine for other ice damage. If you are lucky it will just be the plug. This is why
I always store my boats engine full of 50-50 antifreeze in the winter.Just draining the water
doesn't guarantee its empty.

Last year when I unwinterized my boat a freeze plug had just fallen out without doing any damage to the block.

I bought a brass one and put it back.

Jon did you buy a lottery ticket also it was your lucky day.

Freeze plug saved my engine last winter. Instead of the block cracking the plug popped. Had a new one welded in

What? Welded in? They are suppose to be pressed in.

How to replace a freeze plug and what they are for!

I was really scared when I found it. I was told when I winterized that there was no need for antifreeze in the block. All I needed to do was open up all the petcocks. . . This year I went back to the antifreeze in the block.

Ummm... yea A-dub, that's not a good idea.

Michael,

Core Plugs / Freeze plugs can and do just fall out. It's not uncommon in 350's. I've seen it in everything from the previously mentioned 350's, all the way up to Range Rovers and BMW's. It's just kind of a bad luck thing if it happens to you and you don't catch it.

I've had a 2 seperate race motors that it happened to, 1 I caught as I was pulling out of the shop onto the trailer.... the other, not so lucky.

Mine didn't fall out on the boat until this 4th of July weekend on the second day out on the water last year. Luckily I keep a watchful eye on my guages, and saw my engine temp starting to climb slightly. I thought I had lost the impeller. Opened the hatch and saw water pouring out the block, then saw the plug floating.