PDA

View Full Version : Temperature at which block cracks



TexasLXC275
11-20-2006, 06:24 PM
I've heard that the outside temperature needs to drop down into the low 20's at a prolonged period of time to actually freeze the water in an unwinterized block and consequently crack the block. Is there any truth to this or is the damage point really at temperatures closer to 32?

Pismo
11-20-2006, 06:55 PM
It would all depend on time, if you put an engine filled with fresh water in a freezer at a steady 30 degrees indefinitely it would eventually freeze solid and crack, it would just take a long time. On the other hand if the forecast calls for lows of 25 tonight that means the temp will hit 25ish for a couple hours and slush will form but there probably wont be time to freeze up solid and crack. Salt is a little lower of course. The increased pressure will lower the freezing point a bit but the block is not strong enough to lower it much, esp the freeze plugs. In order to lower the freezing point of water 1 degree C you have to increase the pressure by 135 times above normal atmospheric pressure, so 14psi x 135= a lot of pressure. Also remember water begins to expand at 4 degree C, maxing out right when it freezes and then it begins to contract again as it gets colder. So drain it and get a good nights sleep, takes 5 minutes.

hardcrab
11-20-2006, 08:25 PM
it would take several days of sub-freezing temps to be concerned , even if the boat is in an unprotected enviroment.
if you get in a bind, put a 100 watt drop light in the motor box , that will keep the chill off ......... it really does make a difference

Marlin275
11-20-2006, 08:31 PM
I heard the temp to break is 26 deg for ten hours
in that area
the light bulb trick is a good one
two 75 watt bulbs, if one burns out you're covered
I did that for two months when I bought my boat from Florida.

MOP
11-23-2006, 07:43 AM
It can happen over night in 20ish temps with fresh water, salt needs two or thre days in the teens. We told our late season die hard fisherman not to flush with fresh when we started to get frosts, even if the block did not go oil coolers popped, sea pumps froze, manifolds cracked etc. The oil coolers were the first to go killing engines on the way to the fishing spots, a loud scream and a burnt belt set of a Chinese Fire Drill to get it warmed up in hopes the rest did not get damaged. Our Hi & Dry boat suffered well before the ones in the water as the water will keep the bilge warm well into the freeze cycle. I live in the North East and have been in the marine industry longer then some are old on this board, better safe then sorry don't listen to the BS.

Dr. Dan
11-23-2006, 10:54 AM
:smash: Mine is not Winterized yet, it will be in the next week or so. But I have an Army Blanket over the Engine, then a King Sized Heating Blanket, than another Army Blanket, then the Hatch is closed, then I cover from the Back seat to the Tail Pipes with a Waterproof Tarp,this keeps any Monsoon Rains from reaching any electric source from the Blanket, then I pull down and String Tie my Full Mooring Cover over the whole mess, I run a power cord from the Garage. The Heating Blanket is Therma Statically controlled and shuts off after 10 hours, so I just reset it periodically and all is well.

Keeps the batteries toasty too!

Doc of Bed Bugs! :wavey:

BigGrizzly
11-23-2006, 11:10 AM
It all depends which engine you have and the BMP and humity Every one here is correct I seen Phil senareo in Jersey more than once. Of course Dr. Dan is the best unless you have a buildge dehumidifier and than put on the blaket for insulation, which is what I used to do befor my heated Garage. Makee no mistake, In Iowa where temps go below 0 for weeks the 100 watt bulb may not work.

justleft
11-23-2006, 07:07 PM
When I worked at a HP boat works in IL we would replace allot of
cracked exhaust manifolds every spring.

For some of the $$$$ go-fasts with complicated plumbing we would
mix up a 100 gallons of 50/50 poly-glycol (safe stuff) in an old horse
trough. Fire up the engines until it was blowing out the exhausts and
other orifises back into the horse troff. We could do several boats
before the mix was too watery. Never had one freeze. But pricey !

In the spring we would just fire them up on the hose.

WARNING - If you try to use RV/Boat anti-freeze in your car or boat's
closed system, clogging (not as in river dance) may happen. This stuff
can not run with high heat. (Evan's makes a really pure form that we
ran in our race cars. $$$)

Pismo
11-24-2006, 03:02 PM
Why worry? Drain it, 4 plugs, 3-4 hoses, it takes less than 5 minutes.