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How do you winterize an engine exhaust system? Boat is a Catalina 25 w/Universal diesel engine. Could not find any drain valves for the intake water. Engine has antifreeze. Thought about using a wet/dry vac to suck water out the exhaust at transom. I assume the manifold and muffler are full of water. I can take off the cover from the pump if necessary. Boat is out of the water since Sunday

Prior years I left it in the slip with a heater plugged in
 

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Close seacock for raw water intake. Remove hose from seacock and stick it in a small bucket of antifreeze. Run the engine long enough to suck antifreeze through the exhaust system, making sure not to let your bucket (and thus the engine) run dry.

Some owners install a valve on the raw water intake hose to be able to do this without taking the hose off the seacock.
 

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You will get a lot of answers to this question.

Here is what I do, and I have an M25 in my O'day 35;
I have a sea water strainer between my through hull, and the raw water pump.

I shut the through hull, and remove the cap from my raw water strainer.
I remove the drain from the waterlift muffler on the exhaust.
I drain the raw water strainer, or suck it dry with a shop vac.
I invert a gallon of -60º antifreeze onto the top of the raw water strainer. I also have another gallon ready to go, if this one empties.
I start the engine, and watch the exhaust drain until the exhaust turns purple. I then shut down the engine.
I then take the (empty) gallon of antifreeze off of the strainer.
I then remove the raw water impeller, and leave the cover off.
I remove the zinc from the heat exchanger, and vacuum the liquid as it spills out with the shop vac. I keep the vacuum on the heat exchanger zinc nipple until I start drawing air from the raw water pump.
I then remove the end cover from the heat exchanger, and vacuum out the HX chamber.
Finally, I vacuum out the waterlift muffler from the drain, but I leave the drain plug off until the spring.

Hope this helps...
 

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Most folks will recommend doing something similar to that described above. The biggest change I see is that Maine Sail and others recommend not just running the engine until the antifreeze shows in the exhaust, but actually running it until the antfreeze is essentially full strength at the exhaust. Otherwise you wind up with diluted antifreeze in the pipes and that will increase the freezing/slush point of the mixture in there which isn't a good thing. In the end, in North Texas, you may be OK, but realistically you're probably looking at the cost of one or two more bottles of antifreeze compared to the cost of replacing your engine.
 

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Done the way that I suggest above, the raw water system is primarily full of air, and secondarily a mixture of PG and sea water. The benefit of draining the system is that that any remaining liquid in the raw water system will have plenty of room for expansion, it is likely to have a much lower freeze point than seawater, and I inspect the whole thing as I do the draining.

The components that are being protected from bursting due to freeze expansion are: the seacock, the raw water strainer, the raw water pump, the heat exchanger, the anti-siphon valve, the mixing valve, and the waterlift muffler.
 

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mmm...always brought great comfort to me knowing that
system was protected by corrosion inhibiting anti freeze
rather than left dry and subject to rusting when exposed to air.
 

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... The components that are being protected from bursting due to freeze expansion are: the seacock, the raw water strainer, the raw water pump, the heat exchanger, the anti-siphon valve, the mixing valve, and the waterlift muffler.
Bear in mind that if the raw water impeller is neoprene (some are neoprene, some are nitrile) it will be ruined by PG. In this case, EG is a better choice (does not damage neoprene or nitrile).
 

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Discussion Starter #8
Thanks for the info.
I thought about putting the pink stuff I used in the RV and the potable water system in the boat. Taking things apart to install the antifreeze to get through a couple of days of possible freeze temps during the night seems to be a lot of work. I will put a light bulb in the engine compartment today. I have to run a 200 foot extension cord to get power which should be OK for a light bulb.
 

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My approach

Similar to what others have said, but here are the specifics.

With the boat on the hard:
  1. Drain water from muffler. Allow to drain into the bilge. Recap drain port.
  2. Pull strainer and drain the water from it using a turkey baster. Reinstall strainer basket.
  3. Between my strainer and the water pump, I have a port where I can install a hose, which can insert into a bucket of AF.
  4. Start motor and suck a gallon of -60 deg F Glycol AF
  5. Once the gallon of -60 is gone, I pour in a gallon of -100 deg F Glycol AF.
  6. I run engine until the flowing AF out the back starts to spit.
  7. Shutdown the motor
  8. Drain the muffler again.

Never had an issue with temps down to -10 deg F. Draining the water out of the motor/muffler first results in less AF dilution and therefore the need to use a lot of AF to insure protection.
 
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Not to forget the thu hull for head and sink .Really cold can crack the valve . Close the valve as the antifreeze runs out thru it. Fortunately ,here in BC winterizing means putting on a sweater when you go on deck.
 

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There are several derivations of winterizing an engine system and the complexity revolves around whether the engine is closed loop cooled or raw water cooled. Yours is closed loop if you have antifreeze in the engine.
This is my system also. What I do is once the boat is on land I disconnect the hose from the RW strainer and flush/clean the strainer w fresh water. I connect a hose to the raw water pump and use a bucket with hose and run fresh water thru for 5-10 minutes. Then I put some "salt away" in the bucket and run that thru. When the bucket is just about empty (engine running) I dump in a gallon or so of propylene glycol and run that thru. I shut the engine off just before the bucket empties. Winterizing done.
A word of caution, propylene glycol while not toxic or "bad" for the environment should be contained but lets face it, most of it gets run to the ground. Ethylene glycol is toxic and bad and must be contained. That means if you run EG thru the system you should catch it in a bucket when it comes out the exhaust port for proper disposal.

my 2 cents
John
 
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