Is it necessary to remove t-stat for winterization

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GripB

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I plan on running the engines to operating temperature prior to running the antifreeze through. Some have told me to drain the blocks or remove the t-stats.

Greg

edit: Forgot to mention that the engines are FWC MerCruiser 6.2L MPI Horizons
 
Greg, if you are FWC; the thermostats don't enter the picture. Engine c/b ice cold & A/F will circulate thru raw water side of system.
 
For 25 years I have removed and then replaced the stats after running antifreeze thru, I will do it again this year. Draining the block will work too but rust is a problem with that. 10,000 dollar an engine isn't worth the risk to me.
 
Back when I owned a raw water cooled I/O, I would drain the block, and remove the thermostat. I would then fill the block with antifreeze, by pouring it into the thermostat housing. I am not a believer in running antifreeze through.

MHO
eric
 
If your engine is FWC, then no need to pull the T-stat. The engine is permanantly winterized assuming you have anti-freeze in the closed cooling loop as you should.
All you need to do is winterrize the raw water side.
Assuming you have inboards, if you have a strainer, close the seacock, open the strainer and pour AF into the strainer while the engine is running. A couple of gallons should be enough.
 
+3 if FWC. all you are winterizing is the raw water side: Oil cooler, raw water pump risers and exhausts and heat exchanger.
 
as noted above, FWC or closed cooling has the engine full of antifreeze and the manifolds too if a full system (half does only block)...so your main job there is to get the water out of the raw water side (heat exchanger and impeller housing/lines).
With a raw water cooled engine, if you want to fill with AF after draining, its not necessary to remove the thermostat. Disconnect the big hose that connects the thermo housing and circulating pump, at the top connection (thermo housing neck), leave the bottom one to the pump on. Then just pour in AF the hose till it comes out the neck of the thermo housing. Then the engine's filled, re-connect the hose at the thermo housing and you're done filling the block...
 
Thanks for the help guys, I appreciate it.

And yes, I have FWC inboards. So I'll close the seacocks, take off the cap and continue pouring antifreeze in until I see it coming out of the exhaust, correct?

Can I do the same process (pouring antifreeze in the strainer caps) for the genny and A/C?

Greg
 
quote:
Originally posted by GripB

Thanks for the help guys, I appreciate it.

Can I do the same process (pouring antifreeze in the strainer caps) for the genny and A/C?

Greg

Click to expand...


Yes.
 
Nobody mentioned testing the anti-freeze for its protection level on fresh water cooled engines. If you have a small leak, and your anti-freeze becomes dilluted, you could ruin the engines.
 
+1 on the last comment. When I first winterized my boat (after I had bought it and shipped it from FL that season), I casually tested the antifreeze to 'make sure' it was ok. It wasn't, at least not nearly to MN winter temps. I had it flushed and replaced, and haven't had any issues since. I do still test it every time I put the boat away though, just in case..... The testing tool is only a few bucks and you can test it right out of the overflow bottle.
 
Good point(s) about testing the antifreeze. An antifreeze tester has been added to the list.

Greg
 
greg - my setup is similar to yours (fwc inboards). even at idle, which is how the engines should be run when winterizing, they will suck up the antifreeze very quickly. i found it much easier to suck the antifreeze from a 5 gallon bucket then to pour it into the strainers. so i disconnect the hose going from the strainer to the v-drive and connect a longer hose to a 5 gallon bucket. before using the pink stuff, i fill the 5 gallon bucket once or twice from a garden hose and run fresh water through the cooling side to get any salt out. after i use the pink stuff (and it's coming out the exhausts), i open the seacocks and pour some af manually into the strainers/seacocks. for the winter, i leave the seacocks open (assuming the boat is on the hard). i also open the heat exchangers after the pink has been run through as well as the engine's fresh water fill to allow for any water expansion (even though there is af in both the systems). better to be safe than sorry.
 
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