Running engine to temp for winterization

Do you need to run the engine up to temp so the thermostat opens before putting in antifreeze? All I did was remove all of the drain plugs, drain all of the water out, reinstall plugs, run antifreeze through until it came out the exhaust. So did any antifreeze get into the engine? Also, if you need to run it up to temp before putting in the antifreeze how much time do you have before the thermostat will close? You would need some time to shut off the motor and remove all the plugs to drain re-install and start putting in antifreeze. Is this overthinking?

Your best bet is to remove the thermostat, drain the block, then run with antifreeze, drain block again. That way you know it goes through the block, and mixes with very little water since you already drained it. Next season just put plugs in and a new thermostat and good to go. Not as convenient, but helps me sleep at night to be sure I got the water out and any that's left is mixed with lots of antifreeze.

If your engine wasn't fully up to temp then you probably have antifreeze in your exhaust manifolds and risers but none or little in the block.

How / where do you remove the thermostat? You say put a new one in next year, how much are they? Can't the old one be put back in? Thanks for putting up with noob questions.

don't remove the tstat, just remove the jhose off the tstat housing, suck out the residual water in it and pour the antifreeze down into the circulating pump which will then flow into your block.......the actual thermostat lets hot water out of the engine, fresh cool water comes into the engine via the jtube and the circ pump

Good question actually, i've wondered the same.

Question too is why do you redrain the block after running antifreeze in it? Aren't you better off leaving the Antifreeze in there for limiting the corrosion? Also is RV antifreeze just as good as the old green stuff?

Don't use the old green anti-freeze you need bio-degradable because that anti-freeze goes into the lake water on start up.

If you drained the block first, and then ran antifreeze through the system until it was coming out the exhaust, there will be antifreeze in the block. There could be some residual water that didn't quite drain out, but it will be diluted with antifreeze.

Nick, I drain the antifreeze because antifreeze does have a burst point. I figure by the time I've drained the water, run antifreeze, drained the antifreeze, and then bounced down the highway with the plugs for an hour, everything should be out. I also drain so it doesn't go into the lake come spring.

The thermostat is in the thermostat housing, held down by two bolts into the intake located at the front of the engine. It will have several hoses going into it, one coming from raw water, one to each exhaust manifold, and one to the engine circulating pump.
In this picture it's the metal piece on the intake up front with all the hoses going into it. Yours may look a little different depending on what engine you have but it'll be easily recognizable.


I pull mine for cheap insurance. Draining the block, maifolds, etc. is also cheap insurance. Get as much water out as you can with all the drains (some folks don't even use antifreeze), then run antifreeze through the engine so you know it's not heavily dilluted, then drain that.

In the end you only have small amount of antifreeze/water in the engine which should have very low water content so should not freeze, but if it does it's unlikely it'll do any damage. It's not necessary, and a lot of folks just run it to temp, then run a few gallons of antifreeze through it. I feel better to spend a little more time and be certain. A thermostat is only a few bucks, + gasket(s). Typically yoyu can get a marine thermostat+gasket hit for $20 or less. Do whatever method you're comfortable with.

Also I don't recommend using the -50 pink RV antifreeze. It will freeze at relatively warm temps and turn to slush, but not freeze solid. It does not take much water to make it freeze solid though. I use the -100 antifreeze as it won't slush so quickly and is more tolerant to mixing with water before it'll freeze solid.

Also I don't worry about corrosion. A bit of mild surface rust isn't a big deal and would take longer than the life of the engine to cause a problem. It'll rust no matter what if you have water in it or air. If corrosion is a big concern, switching to a closed cooling system solves that (except manifolds, which I consider a wear item) and simplifies winterization. But by the time your engine gets too much rust or scale on the inside it's time for a rebuild anyhow and it gets hot tanked and cleaned or replaced with a new engine, or you've already upgraded. Even with a lot of scale inside the engine you still have an unlimited supply of cool water to pump through it so no worries.