I freeze my block so you don't have to!

[H20Rat]

Every year there is inevitably a couple of threads of 'how cold is too cold'... I'm going to find out this year!

I winterized my 4.3l last week, and although I'm a firm believer in the air-don't-freeze method, the amount of water left over in the valley under the thermostat is always concerning. After draining/poking, I always pull the thermostat and dump a decent amount of -100 AF in there.

Being an IoT/automation tinkerer, I have plenty of sensors of all sorts laying around, so there is now a waterproof temp probe submerged in the antifreeze in the valley. In theory, as soon as that drops to under 32 or so, any water in an improperly winterized block is going to be turning solid fairly quickly.

As of right now, the block is nice and warm (relatively), but within a week the forecast shows nighttime lows in the low teens and a day with daytime highs in the 20's. As a FYI, the boat is stored in a stick built garage with metal roof/siding, no insulation. The boat is a 21' Hurricane deck boat, the doghouse is propped open slightly. The outside weather temp is from a weather station about 100' away from the garage.

Any bets as to how low or long of an outside temp to get the block down to 32?

 

[Scott Danforth]

20 degrees for 6 hours

 

[Lou C]

If you have a Vortec 4.3 V6 (1996 and later) there is a drain plug in the front of the intake manifold you can remove to fully drain it....

 

[H20Rat]

If you have a Vortec 4.3 V6 (1996 and later) there is a drain plug in the front of the intake manifold you can remove to fully drain it....

Yeah knew about it, but my engine tilts back quite a bit. So not only is the plug somewhat of a pain to get out, I also have to hop back down and crank the jack way down, and then crank it back up to get the water out of the bilge.

Overall time to zip off the 2 bolts holding the thermostat down is minimal, and I get a bit of added assurance of the antifreeze running down through the rest of the water system in case there is any nook or cranny with water left over. (still firmly air-don't-freeze, I don't keep the AF in there)

 

[flashback]

No bets here,

 

[paulswagelock]

Cool experiment. What sensors and software are you using?

 

[H20Rat]

Cool experiment. What sensors and software are you using?

An ambient weather station with a couple wireless Ambient sensors. I use a raspberry pi with a TV Tuner USB running SDR (rtl_433) to grab that signal over the air and then send it to a cloud server via MQTT, which Telegraph grabs and dumps into InfluxDB, finally to be graphed by Grafana. I use arduino's and ESP32's to do the same with other sensors. (like well water pressure, temperature, bbq/smoker, etc)

 

[H20Rat]

Takes way longer to freeze than I would have thought. 10 hours under 32 degrees, the block is at 37 but dropping.




(Also it is way more depressing to visually see mid 70's 5 days ago, and now we aren't going to get above freezing as the daytime high!)

 

[Scott Danforth]

wait until ambient air in the garage falls to 20 and you will see your block temp drop quicker. right now your still at 25ish with an 37 degree block. you have a thermal mass of iron in the 400# range. knowing that ductile iron has a k factor of about 70, you should be able to calculate the temperature drop. now things like if your hatch is open or closed will change the thermal conductivity on the air side.

 

[stresspoint]

If you have a Vortec 4.3 V6 (1996 and later) there is a drain plug in the front of the intake manifold you can remove to fully drain it....View attachment 390764

ha ha Lou , if you can get it out without snapping the plug.
SB V8s also have the drain plug and most times they snap before they come loose , i replace them with brass plugs on all motors as a given.
some i have had to chip out one little bit at a time , it is ok as the plug material is weaker that the cast manifold.

 

[H20Rat]

Experiment over, block is officially 'frozen'. I am honestly surprised, it took almost exactly 24 hours of sub freezing temp for the block to get low enough to freeze water. As Scott mentioned, there is a pretty substantial thermal mass that needs to change temp, and that takes either time or really cold temps.

Obviously, results are going to vary with all kinds of variables (wind, temperature, storage building, boat, etc...), but this does give me a little piece of mind for those early/late season dips into freezing. Even a couple hours overnight down to ~20 is definitely not going to freeze it if it warms up during the day.

Now I'm off to move some more snow and dream about boating!

 

[Scott Danforth]

. Even a couple hours overnight down to ~20 is definitely not going to freeze it if it warms up during the day.

you may want to check that. at -20 there is a potential for a higher delta t, and there is less BTU's to remove to get the block to freeze.

 

[H20Rat]

you may want to check that. at -20 there is a potential for a higher delta t, and there is less BTU's to remove to get the block to freeze.

Sorry probably should have spelled that out. It was a tilde, not negative, approximately... yeah, at -20, its going to turn solid quickly! (and by the time the weather has turned to -20, that block would be long gone)