How do I replace frost plug

[Larry Baloun]

I have a 4.3 ltr tks 2008 mercruiser with water pouring out of the front right side frost plug which is behind the motor mount. How do you get at it and how do you replace it?

 

[alldodge]

Remove outdrive

Place hydraulic bottle jack under motor to support weight. Remove motor mount, and find a socket to just fit inside the freeze plug. Coat plug with aviation sealant, hammer plug into block and remove socket.

Replace mount, check alignment and reinstall drive

 

[achris]

Highly likely that the reason the CORE plug is out is because the engine was full of water and froze. Which means, it's also highly likely the engine block is now cracked.

They are not freeze plugs, or frost plugs, they are CORE plugs. They are there so the sand used in the casting process (called a casting 'core') can be removed. The hole is then machined so a plug can be fitted. They are not there to allow water to expand out if it freezes, that is not how it works.

If the plug has been popped out by frozen water, start looking for a new block (and usually the exhaust manifolds are also damaged, by the same process)...

Chris.....

 

[Larry Baloun]

The 5 blue drain plugs as well as the square intake manifold drain plug were all removed to drain and replaced in the fall ...so it was not full of water. I don't understand how this could happen. Given this situation how should I go forward?

 

[Larry Baloun]

...so how do you "remove outdrive" and "realign" engine mount?

 

[achris]

Were all the drain holes poked and prodded with a bit of wire or a small screwdriver to ensure ALL the water was out?

I would bang in a new (brass) core plug and then pressure test the engine. You'll need to remove the exhaust elbows and fit blanking plates. The using the incoming water hose (removed from the fitting on the gimbal housing) pressurize the block, heads and manifolds with air to about 15psi. If it holds for 20 minutes, you should be sweet.

Question: Why do people put the drain plugs back in before winter? Common sense (I may have just answered my own question) tells me to leave them out, so any water still in can still get out. Just throw them in a placcy bag and secure to the instrument panel. That way you won't inadvertently try to start the engine without the plugs in... Just a thought..

Chris......

 

[achris]

...so how do you "remove outdrive" and "realign" engine mount?

Click the My Videos link at the bottom of my signature.

 

[Larry Baloun]

Thanks Chris, I like your videos. That alignment tool looks like it is a pretty specialized item - not sure of availability. Also do you cover re & re of outdrive anywhere?

 

[achris]

Thanks Chris, I like your videos. That alignment tool looks like it is a pretty specialized item - not sure of availability. Also do you cover re & re of outdrive anywhere?

Alignment tools are available on ebay.

I have videos on removal and re-installation of the drive. Just look down the list...

Chris...

 

[tank1949]

The 5 blue drain plugs as well as the square intake manifold drain plug were all removed to drain and replaced in the fall ...so it was not full of water. I don't understand how this could happen. Given this situation how should I go forward?

You'd be surprised what is left inside block. There should be small NPT (if I can remember) threaded plugs on each side of v6/v8 blocks. Most people forget about those hard to get at little POS. You might be lucky and only had a small amount of water which was just enough to pop out plug.