5 Freeze Plugs Missing

[Bimmerknut]

I have a 351 Windsor in my '97 Fiberform. This boat sat for more than 2 years before I bought it a few months ago. I got the trim water pump rebuilt and the engine running fine with the exception of getting warm pretty fast. Upon further examination, 5 of the 6 freeze plugs are gone. I can get to the others but there are 2 on each side that are right behind the motor mount. Do I really need to pull the motor mounts to do this? If not, what the best method. If so, then what's the best way to secure the engine while the mount is remove and the plugs put in, doing one side at a time?

 

[andrewterri]

wow that is a lot of freeze plugs out. hope you block is okay. I have never replace plugs but will throw out my thoughts until someone who has experience chimes in. The way I have been told it is done is by getting the brass plugs and a socket that fits the outside diameter than a piece of wood between the socket and hammer. Again, I have never done this and only repeating what I have been told.

 

[Scott Danforth]

folks, they are core plugs to get the casting core sand out of the block during the casting process. if they are missing, the block is most likely cracked. the core plugs were never intended to save a block from being damaged when water in the cooling jacket freezes. pull the motor.

with 5 of the 6 core plugs gone, its guaranteed that the motor was not winterized properly and that the block is cracked.

 

[Bondo]

Upon further examination, 5 of the 6 freeze plugs are gone.

Ayuh,..... That's a Sure sign that the motor was left to freeze with water still in it,.....

You can try puttin' the core plugs back in, 'n runnin' it,...... But,.....
Odds are against this bein' a runnin' motor,....
Much more likely it is a freeze busted block,.... aka: an anchor, not a motor,.....

Like Scott says,... Pull the motor, 'n do yer testin' outa the hull,.... much easier,....

 

[Lancer76]

Bimmer,
I'm wondering whether the very short time it takes for your temp sender to hit 3/4 of max (as posted elsewhere) is also an indication of a cracked block sendimg exhaust gas into cooling passages .

 

[Redfred1]

I can remember having a Ford 351 Windsor motor.Had the same problem. Went to a auto parts store; they had a freeze plug kit consisting of a rubber plug; with a bolt and washer thru the center. Got the old one out; this plug slipped in; tightened with a hand wrench. I remember it because it was underneath the manifold by the exhaust. Just a thought.

 

[andrewterri]

my apologizes Scott, I know they are casting plugs but keep calling them freeze plugs. Whoever started that name sure did confused a lot of people. The name has just stuck.

 

[Bimmerknut]

Casting plugs are not the same thing as freeze plugs. Freeze plugs ARE designed to allow the expansion of ice to "give" rather than compromise the block itself, in the event that water rather than antifreeze is left in the block. This has been common knowledge for at least 50 year that I know of, as part of basic automotive skills taught in high schools. IF they were as some say, nothing more than exit ports for sand from casting then they would be they threaded and permanent threaded blanks provided. Not temporary "soft plugs" made of aluminum, steel, and brass.

The block itself is fine. The reason it overheated is because there was only one plug and therefore could not allow the cooling process to occur. After replacing the missing plugs, the engine started fine, ran fine, didn't reach more than 1/3 the temperature gauge.

 

[Bimmerknut]

Bimmer,
I'm wondering whether the very short time it takes for your temp sender to hit 3/4 of max (as posted elsewhere) is also an indication of a cracked block sendimg exhaust gas into cooling passages .

Several of you are not using common sense. If I tell you that 5 freeze plugs are missing, then the block cannot hold water and if it cannot hold water, it's not a cracked block that's causing the overheating. It's the lack of water.

 

[Bimmerknut]

I can remember having a Ford 351 Windsor motor.Had the same problem. Went to a auto parts store; they had a freeze plug kit consisting of a rubber plug; with a bolt and washer thru the center. Got the old one out; this plug slipped in; tightened with a hand wrench. I remember it because it was underneath the manifold by the exhaust. Just a thought.

I bought two of those to keep in emergency cases where a plug might come out. The only drawback is that the rubber plugs do not fit where the motor mounts are. I've used them before. Thanks for bringing that up though.

 

[Bimmerknut]

folks, they are core plugs to get the casting core sand out of the block during the casting process. if they are missing, the block is most likely cracked. the core plugs were never intended to save a block from being damaged when water in the cooling jacket freezes. pull the motor.

with 5 of the 6 core plugs gone, its guaranteed that the motor was not winterized properly and that the block is cracked.

Don't know quite where you got this information but it is inaccurate. In the 50 years that I've been working on automotive engines, everyone I know in the industry knows that they are freeze plugs designed to "give way" in the event that water is left in the block during long periods of freezing. If all they were was exit ports for sand, they wouldn't be temporary. They would be steel and either welded in place or threaded. As temporary plugs they are "soft plugs" made of aluminum, steel and brass, also NOT made of the same material at the block. The plug ALLOWS the ability for the block to expand from ice created due to freezing, and while it doesn't prevent the block from cracking, it does greatly reduce the risk. You guarantee that the block is crack? I can assure you that it is not. After replacing the plugs, the engine started fine, ran fine, and never exceeded 1/3 the temperature gauge. Here in Washington, we don't get the types of long, extended winters as in the Midwest and Northeast. I've lived in North Dakota, Ohio, and Minnesota, where the risks are much higher that a block would be damaged due to extreme low temps for months at a time.

 

[Bondo]

Don't know quite where you got this information but it is inaccurate.

Nope,..... You', 'n yer associates have been livin' the urban legend,....

They are core plugs,,.... the holes are to release the sand, from the castin' process,....

They do help to protect from freezin', but only a light, short freeze,....
If it gets real cold, 'n stays that way, they are no help at all,....

 

[Scott Danforth]

Don't know quite where you got this information but it is inaccurate. In the 50 years that I've been working on automotive engines, everyone I know in the industry knows that they are freeze plugs designed to "give way" in the event that water is left in the block during long periods of freezing. If all they were was exit ports for sand, they wouldn't be temporary. They would be steel and either welded in place or threaded. As temporary plugs they are "soft plugs" made of aluminum, steel and brass, also NOT made of the same material at the block. The plug ALLOWS the ability for the block to expand from ice created due to freezing, and while it doesn't prevent the block from cracking, it does greatly reduce the risk. You guarantee that the block is crack? I can assure you that it is not. After replacing the plugs, the engine started fine, ran fine, and never exceeded 1/3 the temperature gauge. Here in Washington, we don't get the types of long, extended winters as in the Midwest and Northeast. I've lived in North Dakota, Ohio, and Minnesota, where the risks are much higher that a block would be damaged due to extreme low temps for months at a time.

I get my information direct from the foundry that designs and pours the frigging motors. you and your associates have it wrong.

 

[Lancer76]

Wikipedia refers to them as core plugs whose purpose is for casting. The internet is always right...

 

[Redfred1]

What a wealth of information! Anybody who has seen a engine block knows what they are; and they do one thing. "Leak when they are bad or missing". Core; freeze; expansion; I could care less what you call them; they still go bad. Blame it on us Rednecks down here in Texas!

Went to WM yesterday and bought a new "Hose Pipe".

 

[wellcraft-classic210]

So we are glad the hear you Ford appears to have with stood a deep freeze / -- If your oil does not get milky and the engine is running fine it appears you had a good and somewhat rare outcome

Wondering if the Ford block design is more robust in some way -- But as a dedicated GM fan I will most likely go into some state of denial about this.

It might also be noteworthy to mention the numerous other posts on poorly winterized boats & the repeated trend of damage to engine blocks & exhaust manifolds. These cracks are often not easily repaired.

 

[Bondo]

Wondering if the Ford block design is more robust in some way -- But as a dedicated GM fan I will most likely go into some state of denial about this.

Ayuh,.... As I eluded to earlier, it's most likely 'bout the temps, 'n time,.....

A light freeze will push the core plugs out, 'n if it warms, rather than stayin' cold, or gettin' colder, the ice thaws, 'n the water runs out the core plug holes,.....
If it freezes again, there's not enough water left in the block to expand, 'n bust the block,.....

Ford blocks freeze, 'n bust, just like Chevy blocks,.....

 

[Lou C]

And, your first notable symptom of a cracked block is NOT usually overheating, it is usually water in the oil. Look for a milky emulsion on the dipstick and inside the valve covers. An engine with a cracked block can appear to run fine and not overheat on the water hose, but the more you run it, the more water gets pushed into the lube system. Its not the external cracks that cause this but the internal ones, like in the cam valley, under the intake manifold. It will be a little at first but before you know it you will have a real mess in there. These pix are the results of 2 blown head gaskets. There were cracks in the cyl heads from a previous overheat so I replaced them with a pair of reman heads. It took 4 oil changes and running it up to temp for a while to get all the moisture out.

 

[thumpar]

The difference in cost to thread and then plug a hole rather than just put a plug in it would be expensive. When you make a million of each block even if it was only a $1 difference it would end up costing you a million dollars more. We know it would cost way more than that. That is the reason they don't thread and plug it. This is just the cheapest way to make them not protect them.

 

[Lou C]

And it all goes back to what I always say:
all inboards and I/Os should come with closed cooling STANDARD....then we would see very few problems like this....Yes you have to replace the exhaust, but then all you have to do is hook your engine up to an antifreeze tank and run it for 5 min and fog it. No crawling around, dropping drain plugs in the bilge, breaking the stupid plastic Merc ones, none of that! GM intended their cast iron engines to have antifreeze in them, with a pressurized system. It is better in every way except cost.

Merc in particular has gone through a lot of trouble to avoid making closed cooling standard with these stupid multi point systems and after a few years in brackish water, they are an invitation for disaster. Just ask professional techs, they say to take them off. So when I finally re-power, that's what I'm doing and will have a longer lasting, easier to maintain system. Raw water cooling is a cheap, inferior system any way you look at it. Even outboards rust through from raw water cooling here in the salt pond.