Cold Iron

[joe_db]

I was away and did not get to the boat in time to turn the cabin heater up before our cold snap two nights ago. The low for the night was 16 degrees and I only had the heat on 500 watts
I got down yesterday and checked, the engine got down to 33. That was CLOSE, even if our water probably has to be about 29 to freeze. I just couldn't resist starting her up to make sure all was well, which it was.
Cold engine and about 2 minutes after starting shown.

[JustinAlenScott]

Very close! Great check! What kind of machine gives you a great picture like that? I'm very glad you were able to check and found everything in good shape and warmed up nicely.

Now I would like to ask you some advice, if I may, since I experienced the same cold snap and similarly wish my heat was a bit more than it was in the cabin. I do have an old school oil radiator heater plugged in inside the cabin and I left the engine compartment open in hopes that would keep it a bit warmer in there. I haven't winterized the engine because temperatures weren't getting so low until the (thankfully brief) sudden drop and I haven't been overly worried because my motor is Fresh (Green) Water Cooled. So just before the temperature drop I visited the boat (up on the hard) and opened the through hull to the raw water pump and opened the bleeder screw at the peak of the exhaust riser in the port cockpit lazarette hoping that would be enough to evacuate / allow some room for expansion in the coldest places (close to the hull / far from the heater). Hopefully these precautions were enough to prevent at least some of the worst catastrophe if freezing should occur.

What I would like to ask is what obvious logic may I have overlooked and what should I check now for signs of damage? How might these signs present themselves? I am supposing that the parts in question are chiefly the heat exchanger and the raw water pump, then the hoses and fittings and then connection to the exhaust. Should I run the engine out of the water to inspect the working condition of moving parts as you did? Should I run a garden hose into a bucket for the RWC to draw from? Or can I run for a little while without the heat exchanger cooling the exhaust as it normally does?

Thank you for any guidance you might have. I am new to owning the boat and caring for the engine and I am learning a lot here and am as full of gratitude as I still do have so much to learn.

[joe_db]

A FWC engine, as you point out, only has a few places that can freeze. I am lazy, I think I would just fire it up and see if anything leaks.

Here is another photo, this is the exhaust riser starting to warm up:


This is an important safety issue, heater cords. My cord warms up, it could be a bit undersized. This is one reason I rarely run the heat at 1000 watts.

[Al Schober]

Worst case scenario is a cracked block. In my case the crack ran from a coolant passage into one of the valve ports. Salvage yard gave me $10 for the block.
Since then, I've been a big proponent of glycol cooling and a heat exchanger. Of course today I was out in shirt sleeves (mid February).

[edwardc]

Originally Posted by JustinAlenScott

... What I would like to ask is what obvious logic may I have overlooked and what should I check now for signs of damage? ...

In addition to the engine, the drinking/washing fresh water system is susceptible to freeze damage, as well the head & blackwater plumbing. (if you have those systems on your boat)