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A caution for winterizing with antifreeze


iliketoski

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I just wanted to share an experience I just had winterizing with antifreeze.

My normal process is to change the plugs, run the engine on the hose, get to operating temperature, shut down, change oil & filter, restart on the hose to circulate oil.

I then shut down, drain both sides of the block, and the crossover hoses on the exhaust manifold. I then take a bucket of antifreeze with two gallons of antifreeze, put the intake hose in the bucket, start the engine, fogging while it sucks in the antifreeze, shutting down when the bucket is empty. (I've been doing this for 15 years)

This year I rounded off the head of the plug on the engine block drain (couldn't get it out), so I just drained the other side side of the block (with the antiknock sensor), and the exhaust manifolds. Sucked the antifreeze in like normal and figured I was ok, since I figured I was just draining things so that the antifreeze wasn't as diluted.

So, a few days later, I got a bolt extractor socket and figured I'd replace the plug so it would be good for next year. When I got the plug out, clear water drained from the block!

Boy am I glad I drained that side of the block! I then followed up by pulling the thermostat, (which I just installed this fall as well, and dumped a gallon on antifreeze into the top of the block.

After thinking about this, I realized it was a good thing I drained the block first for all these years. I'd bet that the thermostat did not have time to re-open, even though the engine was warm. None of the antifreeze went into the block, it just bypassed to the transmission cooler and into the exhaust manifolds.

Correct me if my thinking is wrong, but thought I'd share for people who may not think they should first drain the block.

Edited by iliketoski
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RV/marine antifreeze is intended to be used full strength, so yes, draining water is best practice. Also, an empty block needs more than 2 gals to fill, so id suggest 4-6 and let some exit the exhaust even if theres still some in the bucket yet to get sucked in.

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I'd bet that the thermostat did not have time to re-open, even though the engine was warm. None of the antifreeze went into the block, it just bypassed to the transmission cooler and into the exhaust manifolds.

Correct me if my thinking is wrong, but thought I'd share for people who may not think they should first drain the block.

You are correct! Best way to get the AF in is to remove the stat. 2nd best way is to use a quick change system (water to AF) - but taking the stat out is best.

I take the stat out on all inboards and I/O's. Use the quick change on outboards.

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It's aways been easier for me to pour antifreeze in through the output line/fitting for the heater on the intake by the thermostat. Either one plug, a hose clamp, or in my case just using the quick disconnect I installed on the heater hose itself. This is after draining the system of all water first.

Edited by greg2vlx
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After thinking about this, I realized it was a good thing I drained the block first for all these years. I'd bet that the thermostat did not have time to re-open, even though the engine was warm. None of the antifreeze went into the block, it just bypassed to the transmission cooler and into the exhaust manifolds.

I'll bet you're right. Sitting in the driveway, even a warm engine, idling, the thermostat is probably pretty much closed. The only time it would open fully would be out on the lake, wide open throttle, for an extended period of time. So trying to pump it though in driveway just sends 90% of the anti freeze straight out the exhaust.

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It's that time of year again and there's always about 10 ways people do the same process, most of which are good. I know the bucket trick is very popular and there are those that swear by it but I'm old school and just sleep better knowing that the block has been completely drained and filled. I've never understood the need to pull the thermostat. Like others I do the following.....

Pour Stabile into fuel system. Run up to temp (this usually happens on the last run to the ramp to pull the boat for the season). While at the ramp I'll fog the engine while the boat is still in the water but on the trailer (wet intake throttle body injection. On dry intake multi-port injection I'll pull the plugs and spray each cylinder).

Wait until boat has cooled enough to not get burned then pull the drain plugs on the block (left and right). This is where I also start my oil change and connected the oil change pump to the oil pan hose (might as well get the oil out while draining the block).

Disconnect the hose between the manifolds to drain the exhaust manifolds (you have to love how they came up with this years ago, you used to have to pull plugs before).

Pull the hose going to the trans cooler and check for and clean out any debris.

Pull the raw water impeller and replace (yeah I do this in the fall and install the impeller. Never had a problem but for those of you with OCD you can leave this out and install in the spring. I just like removing it in the fall to get any water out).

At this point all the water should be drained and if I've timed it right the oil should be out too. I go back through my check list installing the drain plugs, reattaching hoses and checking clamps to ensure everything is back in place and tight. It's now time to fill the block and manifolds.

This is where I seem to differ from most people. I pull the top end of the hose going to the engine water pump and the hoses off the thermostat housing going to the exhaust manifolds. I then pour the AF into the water pump hose until AF starts coming out of the thermostat housing. What this tells me is that the AF has filled the entire block as I'm filling the block from the bottom up. At this point I've used about 3.5 gallons of AF and split the remaining AF in the exhaust manifolds just to be safe.

I replace the oil filter, fill up the oil and the engine is set for the winter. At this point I have about an hour and a half into the process including the casual break to sip a beer during the process. I've been doing this same procedure modifying slightly depending on the boat I'm working on for the past 15 years with no issues. I like doing this all in one shot as at this point regardless of my schedule later the basics of winterization have been completed and the engine is safe for the winter.

There are of course a lot of other areas that I do but those are for the options like a shower. ballast and heater. My process changes slightly based on options installed. And then of course there's the deep clean on the interior and hull but then again the point here was on the engine.

I guess in the end as long as it all gets done correctly the process really doesn't matter but this is what has served me well over the years.

Edited by Bturner
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I forgot to mention - make sure your antifreeze is warm when you suck it into the stat -less engine. Cold liquid can crack a hot block!

I guarantee I've been in much colder lake water than the cool temp of the antifreeze.

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I'll bet you're right. Sitting in the driveway, even a warm engine, idling, the thermostat is probably pretty much closed. The only time it would open fully would be out on the lake, wide open throttle, for an extended period of time. So trying to pump it though in driveway just sends 90% of the anti freeze straight out the exhaust.

I thought the thermostat opened at 160 degrees, to keep the operating temperature of the engine at that temp. Its' not optional, it opens based on the circulating water temperature, so it doesn't matter if your at idle on the driveway, or driving on the lake. Correct?

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I forgot to mention - make sure your antifreeze is warm when you suck it into the stat -less engine. Cold liquid can crack a hot block!

Who heats the lake water before it gets sucked into the motor?

For what it is worth I have thought about this quite a few times. Early season, cold lake, hot motor....you get the picture.

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I thought the thermostat opened at 160 degrees, to keep the operating temperature of the engine at that temp. Its' not optional, it opens based on the circulating water temperature, so it doesn't matter if your at idle on the driveway, or driving on the lake. Correct?

You are correct, I believe the response is more along the line of how long it takes to warm up the motor on the trailer and how long the Tstat will be open, than the function of the Tstat.

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A thermostat does not just pop open fully at one temp. If it "opens" at 160, it will only just be cracked open and will not fully open till maybe 160 (you can see this with the old put the thermo in a pot of water test). This is intentional, it's how it regulates the engine temperature. When the engine is creating more heat, the thermostat opens more to get rid of it. The heat the engine generates is proportional to the amount of fuel it's burning, so sitting in the driveway idling, it's generating very little heat and the thermostat only has to be barely open to get rid of it.

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I think the cold liquid cracking the block problem only becomes relevant it you have been running the engine without any coolant at all. Such as driving you're car after the radiator has boiled over. At this point, the block/heads temp are much greater than 160.

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So, if the block has been pre-drained and the Tstat isn't yet opened............. does the block remain dry until the Tstat gets up to temp? That can't be right........

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So, if the block has been pre-drained and the Tstat isn't yet opened............. does the block remain dry until the Tstat gets up to temp? That can't be right........

You're right, this is alleviated by a small passage in the thermostat housing to purge air.

Most automotive thermostats now have a small hole in them for the same reason, to purge air after a coolant change. Back in day, you either had to drill the hole yourself or remove a heater hose to burp the system.

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You're right, this is alleviated by a small passage in the thermostat housing to purge air.

Most automotive thermostats now have a small hole in them for the same reason, to purge air after a coolant change. Back in day, you either had to drill the hole yourself or remove a heater hose to burp the system.

Are you trying to tell me my MG needs "beeno" to offset the effects of ethanol :whistle: ?

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Who heats the lake water before it gets sucked into the motor?

For what it is worth I have thought about this quite a few times. Early season, cold lake, hot motor....you get the picture.

On a cold lake with the t stat letting in a small volume of water to maintain 160 it is not an issue - of course, With no t stat and cold fluid pouring unrestricted into the engine you could take the block temp from 160 to 40 in a few seconds. That's what I'm talking about. It might not be an issue, but I keep my antifreeze at room temp before use anyway.

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I used to run antifreeze without draining first and watch for the exhaust water to turn pink. Then out of curiosity one time I drained it and put a cup out of each side of the block and the manifolds into the freezer. They were all pink and they all froze! Lesson learned.

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I used to run antifreeze without draining first and watch for the exhaust water to turn pink. Then out of curiosity one time I drained it and put a cup out of each side of the block and the manifolds into the freezer. They were all pink and they all froze! Lesson learned.

That's what I'm talking about!

I'm glad I took the extra step of draining the block before hand for all these years, could have been an unexpected disaster, which is why I brought this up! Maybe this will help someone who thinks they are protected by just sucking in the AF.

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Fully drain and fill with antifreeze through hoses is the way I use to do it. Then I got lazy and just drained it and left it. No issues either way.

Running antifreeze up through the raw water intake seems like a good way to end up with frost damage. Would take an insane amount of antifreeze to end up with undiluted antifreeze throughout the block.

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