RV Antifreeze Draw in only : Test and Results (EX330)

[FMSKI]

Temps dropped today and my neighbor said he could help with pulling the boat out. I piloted the SV211 around to the ramp ~ 10 mins but dang, cold day it was not getting up to full temp. Trailer was waiting in the water, so loaded it on anyway.
Then my RV antifreeze hose was the wrong one. Had some electrical tape to beef up the OD & in the mean-time the engine cooling off more

Revved it up and sucked in 12L of RV straight-up, no draining. Got back to my place and 1st pulled my heater core drain - that looked good, antifreeze/pink there, last year it was pretty clear water. Then I took samples from the block at the knock sensors. It was pinkish but definitely diluted. I am pretty sure my T-stat was near closed, but I do think there is a little circulation port (see pix of gasket)

Put the samples in the freezer @ 0 DegF, -17 DegC. After 5 hours it did freeze into a slushy mix per the photos. In order to crack steel you'd need more force than this mix would apply. But it illustrates the margin of error on the thermostat, the final mixing, and what your low-temp target is. The rest of the system - trans cooler, impeller, water pump, exh manifolds, piping will have nearly 100% antifreeze, as that gets good flow from the impeller outlet.

[bturner]

It's all fun and games until something freezes and cracks......

If you're good with it for your boat, so am I. For the extra time and effort I'll stick with what's worked for me for the last 2 decades and continue to drain/fill. I am in no way saying your method isn't pretty, I just sleep better going with what's worked for me.

The other benefit of going old school is that you get time to look everything over while working on the engine and spot things you wouldn't normally see if you were not pulling hoses and opening drains. I've found plenty of potential issues during the process.

Great information though, thanks for sharing!

[jmo]

If you still have the sample try leaving it in the freezer for 48 hours, I be interested to know if that makes a difference.

just remember, it’s a $5,000 - $10,000 mistake (depending on which engine you have) if it freezes. You will also miss the better part of the ski/boarding season waiting to get it fixed.

Take the extra 20 minutes to drain the water first, sleep well the entire winter knowing your boat is safe.

[MN Ryan]

Note that the guys being conservative here are northerners.
0 F for us is balmy.

[SilentSeven]

Cool experiment. What RPM do you use to ingest the antifreeze?

I would suspect that higher RPMs would circulate better within the block?? Also, sounds like the t-stat condition complicated the results.

[FMSKI]

Have a new impeller; revs were up 2-2500, and drained a 10L jug in 15 seconds. Then refilled to 5L and pulled that in, so 15L total.

My study of theromstats on youtube shows they are more on/off than I expected. So as soon as the temp drops that sucker moves closed. Going onto the trailer, the temp gauge was steady @ say 160 ish but a bit below what I would normally see on a summer run when the heat has had time to soak in.

My takeaways are:
1. For deep frosty conditions, yep you gotta drain it.
2. Also I would use RV to cover any residual spots that draining might have missed, prevent stress on fittings, etc
3. In milder areas RV draw is OK, being mindful of the block PS: Lows past couple of years around here is 5 DegF, so above my freezer temp.
I have a buddy that does nothing, just has an unheated garage with a light bulb afaik. GT40 motor.

I am also thinking of storing outside under a tarp this year to free up my "boat port". Therefore no chance to have a small heater in case.