causes for cracked blocks?

Shaun78

Petty Officer 1st Class
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Oct 1, 2007
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People that have had a block crack on them. How did you winterize the block? If you get all or mostly all the water out and then add antifreeze,how could a block crack? I'm curious.
 

wire2

Lieutenant Commander
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Jun 25, 2007
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1,584
Re: causes for cracked blocks?

Very easy.
Blocks/manifolds crack b/c water left in them freezes. They weren't drained properly.
 

Shaun78

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Oct 1, 2007
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Re: causes for cracked blocks?

I know that, I guess I just want to hear stories on how people winterized there boats and found a cracked block in the spring. (Did they use antifreeze)
 

Shaun78

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Re: causes for cracked blocks?

On a 7.4L engine. How much water will come out when draining the block? On mine the left side block drained alot and the right side only trickled(yes I used a coat hanger to see if it was plugged up) ALot comes out of the manifolds/risers.
 

Bondo

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Re: causes for cracked blocks?

and the right side only trickled(yes I used a coat hanger to see if it was plugged up)

Ayuh,.......... How far in did you poke the wire,..??..??.........
 

1730V

Chief Petty Officer
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Feb 14, 2004
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563
Re: causes for cracked blocks?

Causes? Hmmmmmm? The weatherman=COLD.

It's rare that an overheat cracks a block. There is plenty of smoke noticeable to the all but the clueless boater. Those people tend to burn up car engines too.

DRAIN IT. If you do not know how-find someone that does.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: causes for cracked blocks?

I had my 7.4 sitting on an engine stand when I installed the closed cooling system.

I removed ALL of the soft plugs (AKA "freeze" plugs by some uninformed people)

I noticed that the water jacket had about 1-2 inches of rust flakes and sand at the bottom of the cooling system . So much so that on one side the sand was well above the drain hole.

Poking a wire in there didn't produce any additional water until I was able to get all the sand and debris out.


With all the soft plugs out I was able to see in there pretty good and was able to flush ALL the sand, rust and other debris out of the cooling system. THERE WAS A LOT....more than I would have expected. It's VERY common to have sand and rust covering the drain holes to the point that a wire doesn't get it all out.


You MUST ENSURE that all the debris is out of an engine that you are draining.

I would take it a step further and run the engine with the out-drive in a bucket or tub with a gallon or 2 of anti-freeze in it long enough to ensure that the thermostat is open.

Even though i have closed cooling I still did this to ensure that the drive, raw water pump and associated plumbing has a 50/50 mix of AF in them.



Cheers,



Rick


















On a 7.4L engine. How much water will come out when draining the block? On mine the left side block drained alot and the right side only trickled(yes I used a coat hanger to see if it was plugged up) ALot comes out of the manifolds/risers.
 

whywhyzed

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Feb 1, 2005
Messages
1,871
Re: causes for cracked blocks?

I haven't lost a block, but lost a manifold on my first i/o boat years ago because I didn't poke a wire up the drain.
 

njlarry

Petty Officer 1st Class
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Sep 13, 2005
Messages
330
Re: causes for cracked blocks?

IMHO I suspect alot of blocks get cracked by the use of muffs and flush kits. For a varity of reasons the thermostat may not fully open and the antifreeze never replaces all the water. As posted above, blocks freeze because they were not drained. I drain first with engine level then add AF then drain again to get a sample to test. Don's sticky note should be your winterizing bible.
 

dmcb

Petty Officer 3rd Class
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Oct 13, 2007
Messages
93
Re: causes for cracked blocks?

And note carefully what he says about having the proper manual.
I have never seen a manual suggest pumping antifreeze.
All I have seen says DRAIN. Some say then add antifreeze but it is for corrosion protection, not freeze protection.
Air doesn't freeze and break anything should be etched on your engines.
It just boggles my mind at the number of people who attempt to winterize their engines that have to ask how to do it.
That is expensive iron you are working on and we will hear again from many in the spring.
If you have the manual and need clarification, that is one thing but every system is a little different. Thus the manual. A good one will have pics and will answer the questions.
Off soap box now.
Doug
 

njlarry

Petty Officer 1st Class
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Sep 13, 2005
Messages
330
Re: causes for cracked blocks?

The problem is the manual may say "drain" but how do you know for sure no water was trapped? Even if you probe the drain how do you probe all the water passages? AF is cheap enough and auto AF adds some corrosion protection.
 

Shaun78

Petty Officer 1st Class
Joined
Oct 1, 2007
Messages
276
Re: causes for cracked blocks?

That why I do both. Drain and antifreeze. You can't go wrong and no worries WHAT IF. If you drained it properly and then add antifreeze-It will protect your engine from freezing and corrosion. no brainer for me.....
 
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