My test of the "Anti-freeze only" winterization process

[tpenfield]

Here is a video that I put together showing the adverse effects of using an "antifreeze only" approach to winterizing your boat engine (I/O).

This test was done on the AF that would be left inside a Mercruiser 7.4L engine after sucking 4 gallons of -50F antifreeze and not draining it.

A couple of points to make:

- The AF freezes up long before -50F

- Any dilution of the AF with remaining water in the engine can reduce the amount of protection

- The samples in this test were much more frozen than the reference sample of pure AF, showing that the AF that remains in the engine is diluted by the water in the engine. It does not do a 1-for-1 swap.

- You would have to run perhaps 8-10 gallons of AF in order to get sufficiently high concentration of AF and purge all of the water in the engine

- Engines setup with a direct feed to the exhaust elbows will be even worse than the results shown in this test, as much of the AF will by-pass the engine and go straight out the exhaust elbows.

- So, even if you do the AF thing . . . drain the block and manifolds at a minimum.

Enjoy

 

[Grub54891]

I'd kike to see -100 test also. Heck,I'll do it myself......

 

[shrew]

That's why I use -100 on the Engine and -50 for the water lines and AC. With the water pump for the freshwater turned off, the taps are opened and any expansion has a means of egress. The AC discharge is automatically open as is the air vent for the holding tank and head. This allows all the systems with -50 to have room for expansion. I've never had a problem in New England with -100 in the engine.

 

[oldjeep]

Good demonstration. I do use -100 AF for the corrosion protection but drain everything completely first.

 

[tpenfield]

Yea, in my earlier and less informed days of I/O engine ownership, I had a sea water strainer on the intake line to the sea water pump (Merc/Bravo 1) and ran 5-6 gallons of the -50F stuff. The strainer had a plastic bowl (rather than glass/metal) and each year the bowl would be cracked.

It would seem that the occasional -10F or -20F days over the winter would be enough to crack the plastic bowl, eventhough the spec for the AF was for -50F . . . the spec probably applies to a pipe bursting limit.

I'm sure the -100F variety is a whole lot safer.

 

[Chris1956]

Yes, That is why using the flush device to replace the water with A-F is a unreliable method. You must drain the block and manifolds, use some A-F to bleed out the last of the water, install the drains and then fill the block and manifolds. Don't forget to pour some A-F down the raw water hose to flush out the power steering cooler, if you have one.

 

[smokeonthewater]

Air Doesn't Freeze.............

 

[oldjeep]

Air Doesn't Freeze.............

Yes, but it promotes all sorts of rust - especially bad in blocks with knock sensors.

 

[H20Rat]

So, I'm not in favor of the antifreeze method, but your demonstration proves nothing. Freezing is NOT a problem! Yes, you read that correctly. Thermal expansion is the issue, which you didn't show in your test. Do it again using a graduated cylinder, so you can show how much it expanded vs the liquid state.

 

[Starcraft5834]

Brilliant!:clap2:

how did the empty bottle fair? :drum:

 

[Bondo]

Yes, but it promotes all sorts of rust - especially bad in blocks with knock sensors.

Ayuh,.... For Us sweetwater boaters, I truly believe that rust isn't any greater, nor lesser, whether ya store dry, or with antifreeze,....

The only build up of Crud I've ever found was more sand, 'n debris, than rust,....

 

[tpenfield]

So, I'm not in favor of the antifreeze method, but your demonstration proves nothing. Freezing is NOT a problem! Yes, you read that correctly. Thermal expansion is the issue, which you didn't show in your test. Do it again using a graduated cylinder, so you can show how much it expanded vs the liquid state.

I knew somebody would say that !!!

 

[oldjeep]

Ayuh,.... For Us sweetwater boaters, I truly believe that rust isn't any greater, nor lesser, whether ya store dry, or with antifreeze,....

The only build up of Crud I've ever found was more sand, 'n debris, than rust,....

Well, not sure how many modern boat engines you've looked at - GM FI motors with knock sensors, but they (the knock sensors) rot like crazy since they are plain steel. Keeping them in antifreeze helps keep them from rusting themselves to the block. For $20 worth of antifreeze, I'll corrosion protect the $8,000 motor in the off season.

 

[amanphoto]

Question.. Was the engine allowed to run till warm to make sure the thermostat was open allowing full circulation through the engine? I was also told not to use the Pink stuff in the engine. Use car antifreeze in the engine - It protects the block from rust and lubricates the parts.

 

[oldjeep]

Question.. Was the engine allowed to run till warm to make sure the thermostat was open allowing full circulation through the engine? I was also told not to use the Pink stuff in the engine. Use car antifreeze in the engine - It protects the block from rust and lubricates the parts.

The green stuff is toxic an has no place in the open part of a marine cooling system. You don't want that stuff in a lake or down your storm sewer. The proper marine antifreeze also protects the block from rust.

 

[thumpar]

I am more worried about rust from being full of water half the year that rust from being empty for the other half. Even my 1983 engine that I had was clean water coming out. When poking the drains nothing ever comes out. I know that exhaust parts can rust through if you boat in waters that promote rust but show me an engine block that has rusted through.

 

[airdvr1227]

I worked at a dealership that did hundreds of winterize jobs on I/Os. They had a tank of a mixture that was called 'blue pop'. In the tank was a bilge pump that was connected to muffs. The tank also had a catch pan that collected what was coming out of the exhaust and sent it back to the tank. They hooked the muffs up and fired up the bilge pump, then started the motor and let it run. Here's the part I don't get. They used a gadget that they looked through and they could tell the concentration of what was coming out of the exhaust. When they liked what they saw they shut it down. Winterized my other boat that way for three seasons... never a problem.

 

[RotaryRacer]

Yes. Use a refractometer to see the freeze point of the fluid coming out. That is how I do it. Start with -100 Blue and also drain the blocks/manifolds then run the engine with the pump & catching everything that comes out to recirculate it. Typically if you drain everything well you can use a mix with a freeze point at -50 and the remaining water in the exhaust/engine will still dilute it down to -30 or so. Where I live/work -30 or so is plenty adequate with the knowledge that the mixture will just start to slush at that temperature. It is important to let the engine run long enough to confirm the thermostat has opened.

 

[bruceb58]

If you are worrying about knock sensors rusting out on a fresh water boat, you are worrying too much.

 

[oldjeep]

If you are worrying about knock sensors rusting out on a fresh water boat, you are worrying too much.

I only worry about it because I've seen so many pictures of rusted out knock sensors that people are having trouble removing and breaking off in the block due to corrosion. I guess I'm crazy for doing something about it, but for $20 I'll keep doing it.