mercruiser 3.0 freeze plug blew out

[cdoo1972]

Hi everyone. I'm new to iboats and to boating and need some insight. Yesterday while I was replacing the floor section over the fuel tank I noticed something in the bilge. A freeze plug. I looked on the block and found the plug between the #3 and #4 cylinder popped out. I opened the drain and water came out. I was surprised because when I winterized it I ran 5 gallons of coolant threw it. I pulled the manifold and the head. I don't see any apparent cracks. Just a bad spot in the head gasket between #2 and #3 cylinder. I checked the oil its clean and not overfull. So I have a few questions before I start reassembly.
Is a crack easily spotted?
What's the best way to check for a crack?

 

[Fishermark]

Re: mercruiser 3.0 freeze plug blew out

Living in SW Florida I am certainly no expert at freeze cracks.... but.... as I understand it, you would not have any evidence of water in the oil, etc till the engine is run.

 

[Bondo]

Re: mercruiser 3.0 freeze plug blew out

Hi everyone. I'm new to iboats and to boating and need some insight. Yesterday while I was replacing the floor section over the fuel tank I noticed something in the bilge. A freeze plug. I looked on the block and found the plug between the #3 and #4 cylinder popped out. I opened the drain and water came out. I was surprised because when I winterized it I ran 5 gallons of coolant threw it. I pulled the manifold and the head. I don't see any apparent cracks. Just a bad spot in the head gasket between #2 and #3 cylinder. I checked the oil its clean and not overfull. So I have a few questions before I start reassembly.
Is a crack easily spotted?
What's the best way to check for a crack?

Ayuh,.... Welcome Aboard,..... Did ya Drain it, Before ya ran antifreeze through it,..??

If not, ya didn't really winterize anything but the exhaust manifold,...

Sure wish ya hadn't torn the head off,...
Yer pressure testin' capabilities went out the window at that point,...

As for Seein' a crack, ya probably Won't,...
Internal block cracks are usually behind the oil pan in the lower block, opposite the drain plug, inside,...

At this point, 'bout all you can do is put it together, 'n light 'er off, hopin' for the Best,...
If it's Cracked, you'll see it in the oil after that,...

 

[skydiveD30571]

Re: mercruiser 3.0 freeze plug blew out

Living in SW Florida I am certainly no expert at freeze cracks.... but.... as I understand it, you would not have any evidence of water in the oil, etc till the engine is run.

And even then, many times they take several hours of running to manifest themselves.

This is why simply running antifreeze into a marine engine is not a good way to winterize. Unless the engine is hot, the thermostat will be closed and no AF gets to the block. ALWAYS drain the block and manifolds of water first, then add AF if it makes you feel better. Best of luck to you, hopefully you got lucky!

 

[cdoo1972]

Re: mercruiser 3.0 freeze plug blew out

I ran it on the muffs with water until it got to temp then I switched it over to coolant. I took almost 4 gallon before I saw coolant coming out the exhaust. I then added another gallon for extra measure.

 

[cdoo1972]

Re: mercruiser 3.0 freeze plug blew out

One thing I don't understand. If the block cracked internally, why wouldn't the water seep into the oil pan and raise the oil level?

 

[Bondo]

Re: mercruiser 3.0 freeze plug blew out

I ran it on the muffs with water until it got to temp then I switched it over to coolant. I took almost 4 gallon before I saw coolant coming out the exhaust. I then added another gallon for extra measure.

Ayuh,.... If ya didn't stop, 'n drain the block, 'tween the water, 'n the antifreeze,...
Yer odds are 50/ 50 whether it's properly winterized, or Not,...

You Lost,...

One thing I don't understand. If the block cracked internally, why wouldn't the water seep into the oil pan and raise the oil level?

The Hole was bigger where the core plug blew out,....
That don't mean there is, or isn't more freeze damage elsewhere,...

 

[bonzoscott]

Re: mercruiser 3.0 freeze plug blew out

Don't know if you got a cracked block yet. You have to run it up to a good temperature, block expands, crack opens up, pressure forces it into the oil. You might put the head back on and try a cooling system pressure test.

 

[fishrdan]

Re: mercruiser 3.0 freeze plug blew out

Since you have the manifold off, check closely right below the block's deck (about 1/2") and then between the 2 freeze plugs,,, this is where 3.0's "like" to crack.

I'm with Bondo, not much testing you can do since the head is off,,,, beyond totally tearing the block down and having it magnifluxed, which I would not recommend.

You could look for rust streaking under the manifold, or rust marks indicating a crack, but that may not tell much, especially if it's an internal crack.

Bolt it back together and see what happens... Maybe you dodged a bullet?

 

[cdoo1972]

Re: mercruiser 3.0 freeze plug blew out

I see...OK, so my thoughts are: pour coolant down the journals at the rear of the block to make sure the 2 plugs behind the flywheel aren't popped also. Replace the 2 freeze plugs on the side and the 2 in the head. Check the head for true. Reassemble with new gaskets and run it or pressure test it and hope for the best. To pressure test it I'm thinking of making a tee out of pipe. One end would have a gauge, one with an air fitting with a shut off and the other end would go onto the hose coming from the drive. Does that sound right?
How much psi should I pump into it?

 

[cdoo1972]

Re: mercruiser 3.0 freeze plug blew out

I must have read every post on here and a hundred on Google from other forum and every picture I see is what you describe fishrdan and I see nothing on my block. I do know the freeze plug that blew out was weeping over the boating season so I'm hoping the seal was weak enough to blow out before any block damage occurred.

 

[thumpar]

Re: mercruiser 3.0 freeze plug blew out

You may have run 5 gallons of antifreeze out the exhaust unless you drained it first. That means it may not get much in the engine. Those are not freeze plugs they are core plugs used to fill the hole that was needed for manufacturing.

 

[Scott Danforth]

Re: mercruiser 3.0 freeze plug blew out

stop calling it a freeze plug. its a core plug to get the casting core sand out.

you FUBAR'd the winterization. cross all your fingers and toes and hope to hell you didnt crack the block. If your block made it, run to a store and buy a lottery ticket because you are one lucky @#$%@#$%

for your pressure test, you pressurize to 15psi and hold. the system should hold 15psi almost indefinately

next fall, when you winterize it. pull the drains, put them in a bag tied to the throttle linkage, pull the hose to the outrive and drain all the water out of it, and then leave the hose off, and the drains open until spring.

 

[Bt Doctur]

Re: mercruiser 3.0 freeze plug blew out

Somehow I get the feeling were going to hear more of these popped plug posts from improper winterizing.

 

[wrench 3]

Re: mercruiser 3.0 freeze plug blew out

The trouble with just pumping the antifreeze through is that you warm up the engine to open the thermostat, but then the cold antifreeze hits it and it closes before much gets in.

To pressure test you'll have to block of the hose going to the manifolds first.

When you pull the drain plugs to winterize, when the water stops flowing run a wire through the hole to make sure it hasn't plugged up.

 

[havoc_squad]

Re: mercruiser 3.0 freeze plug blew out

Somehow I get the feeling were going to hear more of these popped plug posts from improper winterizing.

That's why overkill this winter on winterization was a very good idea. I'm so glad I drained all possible water after engine was fully warmed up, before running 100% RV/marine antifreeze through the coolant system via the muffs. Then drained everything again for good measure.

There shouldn't be a drop of water in that block, manifold, or outdrive that isn't protected to -5 F or better.

I fear there will be many inboard boats this year that didn't survive the near 2 to 9 degrees F that engulfed most of the mid US.

 

[Bondo]

Re: mercruiser 3.0 freeze plug blew out

That's why overkill this winter on winterization was a very good idea. I'm so glad I drained all possible water after engine was fully warmed up, before running 100% RV/marine antifreeze through the coolant system via the muffs. Then drained everything again for good measure.

There shouldn't be a drop of water in that block, manifold, or outdrive that isn't protected to -5 F or better.

I fear there will be many inboard boats this year that didn't survive the near 2 to 9 degrees F that engulfed most of the mid US.

Ayuh,.... Or just Drain everything, 'n it's Safe to well below -100?, as Air Don't Freeze,......

 

[81 Checkmate]

Re: mercruiser 3.0 freeze plug blew out

opcorn: ........Just waiten on March/April to roll around.....To be continued!

 

[wrench 3]

Re: mercruiser 3.0 freeze plug blew out

That's why overkill this winter on winterization was a very good idea. I'm so glad I drained all possible water after engine was fully warmed up, before running 100% RV/marine antifreeze through the coolant system via the muffs. Then drained everything again for good measure.

There shouldn't be a drop of water in that block, manifold, or outdrive that isn't protected to -5 F or better.

I fear there will be many inboard boats this year that didn't survive the near 2 to 9 degrees F that engulfed most of the mid US.

-5 wouldn't do much good around here this winter. We've hit -32F so far and we're "down south" as far as Canada is concerned. That's why I always put a little antifreeze in through the hoses to the oil coolers, manifolds, circulating pump, etc. Just for peace of mind.

 

[Starcraft5834]

Re: mercruiser 3.0 freeze plug blew out

if there was ever a winter to prove once and for all to just drain the darn thing and leave it empty. this is it...... I read my manual, researched how others winterize,, I chose to listen to elders,, ie- Bondo's "air dont freeze".. made sense to me.. that's what I did, drained it, used compressor to blow it out and left her there covered up,,, will report this spring how that worked out...