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for those who think thermostat has to be open


wheelman

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http://www.boatinghowto.com/content/how-boat-cooling-systems-work-240/

Not sure if this has been posted before but with it getting to winterizing time of year and the posts of saying that antifreeze will not go through block with closed thermostat thought I would share how water or antifreeze flows through an engine with thermostat open and closed. I am not saying how you should winterize, just showing that it does indeed go through motor with closed thermostat and not straight out the exhaust like many say.

  • Like 1
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http://www.boatinghowto.com/content/how-boat-cooling-systems-work-240/

Not sure if this has been posted before but with it getting to winterizing time of year and the posts of saying that antifreeze will not go through block with closed thermostat thought I would share how water or antifreeze flows through an engine with thermostat open and closed. I am not saying how you should winterize, just showing that it does indeed go through motor with closed thermostat and not straight out the exhaust like many say.

Wheelman, you're own post doesn't agree with the above statement.

In the example above notice with the thermostat closed how the orange arrows show the closed circuit flow of the water from the engine through the thermostat assembly to the engine circulating pump and back to the engine. The cold water from the water inlet (blue arrows) flows to the thermostat assembly and is routed to the exhaust risers where it is discharged overboard.

The only water circulating through the engine while the thermostat is closed is the water already in the engine (orange arrows). The fresh water/anti-freeze (blue arrows) IS going straight through the exhaust while the thermostat is closed.

Edited by mattm
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Practically speaking, bleed holes or no bleed holes should not change the analysis if the question is "if I put my raw water intake hose in a bucket of antifreeze, am I good when I see antifreeze out the exhaust?"

If you didn't drain everything first, even with bleed holes at the tstat, at best you'd have *some* antifreeze diluting the water in the block vs none.

Now I guess if you ran 50 gallons or so through you might be better off, but who wants to do that? There's really no shortcut to draining the block, exhaust, vdrive and heater. If you want the comfort of antifreeze, do it after you drain.

  • Like 2
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http://www.boatinghowto.com/content/how-boat-cooling-systems-work-240/

Not sure if this has been posted before but with it getting to winterizing time of year and the posts of saying that antifreeze will not go through block with closed thermostat thought I would share how water or antifreeze flows through an engine with thermostat open and closed. I am not saying how you should winterize, just showing that it does indeed go through motor with closed thermostat and not straight out the exhaust like many say.

Mattm is on the money.... the reason water is flowing in the engine is it has the same basic water pump as our vehicles so if the motor is running it flowing but its like a small closed system, flowing only in the block for the most part. So in a vehicle not through the radiator. In our boats same through the block but not dumping cooling water into the block.

this is why we have a raw water pump. It's pumping lake water into the exhaust to cool the exhaust at start up only when the thermostat opens lake water starts to flow to the block.

Edited by Sixball
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^^^ this is exactly right.

Wheelman's original post and that article puts folks at risk. An $8-10k risk.

That article and this thread are yet another reason to drain the block, tranny, Vdrive and exhaust properly and skip the AF.

No reason to forgo antifreeze you do need to understand how you are getting the antifreeze into the engine. Also how your V drive is plumbed. But I agree with you if you don't know what you are doing it is likely best to drain and not add antifreeze. As brought up on this site if you are using pink RV antifreeze you want it at full strength. If you see extreme cold you may not want to use the pink RV antifreeze you may need to go to a automotive strength antifreeze.

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I hear you.... But all that costs more, more steps, according to manf not required, and dumps crap into our waterways.

I flush out the AF into a Rubbermaid tub with my flush pro. I then take it to landfill, where they recycle it.

Edited by ryangb
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It is possible for antifreeze to freeze. Its also possible for air to freeze but if that happened your boat engine won't be your biggest problem.:D

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It is possible for antifreeze to freeze. Its also possible for air to freeze but if that happened your boat engine won't be your biggest problem.:D

Particularly, the RV antifreeze (pink stuff) is designed to freeze. Usually more of a slush than solid. But when it freezes it doesn't expand. This is another reason you should drain first because a mix of antifreeze and water can still crack the bloc as the antifreeze will indeed freeze (but not expand) and when the water freezes it will have nowhere to expand. And than you have a crappy spring.

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The pink marine/rv antifreeze is best served 100%. So for the best freeze protection, you need to drain the block prior to adding the rv/marine antifreeze. Since air freezes @ -360.9* F, just draining the water is sufficient for freeze protection. Adding the rv/marine to a drained block adds a payer of rust protection.

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I think what is being cooled on the V drive boats is the Walters portion the actual part that changes the direction of the drive not the transmission. You still have a transmission and I think it is oil cooled like a DD boat. I am saying THINK as I have not dealt with A V drive for many years.

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Boat transmissions, whether its a v-drive or DD, typically have a cooler. They are external with a fluid in and fluid out line and the raw water flow passes through the cooler. These coolers can hold water, so its recommended to drain them. Some have an actual drain plug, whiles others, its easy to just pull one of the raw water hosed off and let the water drain.

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Boat transmissions, whether its a v-drive or DD, typically have a cooler. They are external with a fluid in and fluid out line and the raw water flow passes through the cooler. These coolers can hold water, so its recommended to drain them. Some have an actual drain plug, whiles others, its easy to just pull one of the raw water hosed off and let the water drain.

I concur on this. That is one of the primary hoses I remove as part of winterizing. I also do a crap clean of the honeycomb in the tranny cooler. There is always something in there that shouldn't be.

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If you want to add antifreeze and have a heater:

What I did is use the heater hose and a small drill mounted pump to fill the block with AF until it comes out of the exhaust AFTER draining it of water. Then I re-drained the AF. For me I do it for corrosion prevention not crack prevention.

AF can freeze but it WILL NOT expand and cause problems like water will (crack block).

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When you drain the block, make sure you open or remove the plugs from both sides of the block, not just one side. A key item to consider when going through the process, particularly as you look at the original video, is when filling with antifreeze unless doing via the suction side of the raw water pump with the engine running, you will probably be adding in the reverse direction of flow, so the t-stat will be the first thing encountered rather than the last as per normal operating flow path. Heaters, trans coolers and exhaust manifolds are all the additional marine parts added to a basic car engine & need to be drained.

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  • 6 years later...

Hi Guys,

I realize this post is 6 years old... But I was reading through it and the link no longer works. Can anyone reshare a new link? I was just hoping to get more info on winterizing with the T-stat. I recently heard that the T stat does not need to be open if the block has already been drained. Just wanted to get some more info on that!

Thanks!

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25 minutes ago, jas1068 said:

Hi Guys,

I realize this post is 6 years old... But I was reading through it and the link no longer works. Can anyone reshare a new link? I was just hoping to get more info on winterizing with the T-stat. I recently heard that the T stat does not need to be open if the block has already been drained. Just wanted to get some more info on that!

Thanks!

pull the top of the big "J-Hose" off. You can pour AF directly into the block through that. Keep the block petcock open as you start to pour some AF in to help convince yourself the block is actually filling up. When some AF comes pouring out of the bottom of the block - close the petcock and fill her up. I get 2 gallons of AF in before everything is full in my 2000 VLX.

If you want to run more through the systems with your fake-a-lake then that's a personal decision. T-stat open/close becomes irrelevant at this point.

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