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Winterizing the C310 engine?

Apr 19, 2020
20
Catalina 310 Kenosha, WI
First time winterizing my 310 with the Universal M-25XPBC and wanted to know how others handled the engine specifics? I'm storing the boat at the marina where I keep it and was thinking of following the process I put together below. The boat is used in fresh water only.

Supplies to purchase and have on hand:
5 Gallons RV Anti-Freeze (-75 degree)
1 Gallon Shell Rotella T4 (need 3.5 qt)
1 Universal Oil Filter
1 Bottle of Diesel additive

Day of haul out - At the dock:
Fill fuel tank and add the diesel additive
Check engine anti-freeze quality
Run engine to warm, shutdown, then drain engine oil, change oil filter and refill with new oil
Do haul out

Day of haul out - On the hard:
Ideally while the engine is still warm...
Disconnect the two hose clamps to the intake seacock and connect a temporary 3/4" 5 foot long hose
Place the other end of temporary hose in a tub filled with rv anti-freeze set in the bilge area near the seacock
Be ready to add several gallons of RV anti-freeze to the tub quickly once the engine is started
Start the engine and allow 5 gallons of anti freeze to be drawn in and then immediately shutdown the engine

Questions?
How often to change fuel filters (first and second stage)?
Remove anode rode from heat exchanger for the season?
Remove the water pump impeller for the season?
Do you change the transmission oil annually?
Empty the seawater strainer?
Close seacocks for the seasons after draining them?

thanks!
 

Tom J

.
Sep 30, 2008
1,670
Catalina 310 Quincy, MA
Sounds like a good plan for winterizing the engine. Don't forget to do the same for the fresh water tank and system, and the bilge pumps and hoses.
It's a good idea to change the primary fuel filter each season, and the secondary every other season.
No need to remove the anode from the heat exchanger. Remember to check it at the beginning of next season.
No need to remove the impeller. Maybe change it at the beginning of next season.
No need to change tranny oil. Follow manufacturer's recommendations, usually every 200 to 250 hours.
No need to empty the seawater strainer. By now it is full of anti-freeze.
I usually close the seacocks to keep out bugs and debris.
Keep up the good work.
 
Jan 19, 2010
661
Catalina 34 Casco Bay
Add the fuel additive, motor to the fuel dock and top off.. This will ensure a good mixture..

A large pair of channel locks (18") will help remove the oil filter. You can get on it at the engine block end. I only spin the new one on hand tight, but it takes mechanical advantage to remove...

Leave the fuel filters for spring commissioning..

When winterizing the the raw water system, a short piece of hose is inserted into the exhaust flange on the transom. This feeds the exhausted water and channels it into a white PVC gutter section. This allows for visual inspection to see how well the PINK rv antifreeze is displacing the existing water in the system. Against the white gutter it will start out light pink because of the water already in the system.. When you see it darken, you're done.. Leave the zinc in place until spring..
 
Jan 4, 2006
3,114
Hunter 310 West Vancouver, B.C.
Run engine to warm, shutdown, then drain engine oil, change oil filter and refill with new oil
Do haul out
Don't know if I missed this or it's just too obvious, but don't forget to run the engine for a few minutes AFTER the new oil has been installed. This will ensure the engine interior has been flushed with fresh oil for the winter.
 
Last edited:
Sep 23, 2009
1,406
O'Day 34-At Last Rock Hall, Md
I have the same engine. Your plan is good. I change the trans fluid every year, leave the seacocks open, change fuel filter every other year around 100 hrs and disconnect the batteries. I leave the impeller in and replace every two or three years. Zinc is checked once a month in season. I have the admiral catch the last moments exhaust and check the specific gravity with a refractive hydrometer. Being in colder climate you might want to do so to sleep better over the winter.
 
Jul 1, 2010
767
Seaward 25, Catalina 350 Erie, Pa
This gadget from Seaflush makes winterizing the engine a breeze.


An antifreeze refractometer is a good tool to have. Check the bottle of antifreeze, then check what comes out of the circuit you are winterizing and make sure the concentration is the same. I use about 2 gal of -100 to do the engine on our 350. Engine does not have to be warm. You're only doing the seawater circuit.
 
Jan 19, 2010
661
Catalina 34 Casco Bay
Don't know if I missed this or it's just too obvious, but don't forget to run the engine for a few minutes AFTER the new oil has been installed. This will ensure the engine interior has been flushed with fresh oil for the winter.
That "run" is when the RV antifreeze is sucked up ...
 
Jan 7, 2011
2,049
Oday 322 East Chicago, IN
That "run" is when the RV antifreeze is sucked up ...
And when he motors to the well to get lifted out by the travel lift. and if I need to, I hit the pumpout dock too the morning of haulout. At least that is how I do it.

Greg
 
Apr 19, 2020
20
Catalina 310 Kenosha, WI
All excellent advice! Thank you so much for sharing your experience and knowledge with me. I'll probably be back in the Spring with another post for launching boat! ;)
 
Dec 16, 2011
213
Catalina 310 Atlantic Highlands
Don't forget to pump out the holding tank before haul-out! I don't see that on anyone's list of things to do. I also send pink antifreeze through the entire head system, including pumping some into the holding tank.
How often to change fuel filters (first and second stage)? - I started changing them every year, but that is probably overkill as other have noted.
Remove anode rode from heat exchanger for the season? - I replace this every year at the start of the season...mine is usually so degraded that I would be afraid not to.
Remove the water pump impeller for the season? - I don't remove it, but at the start of every season I replace it (so I guess essentially the same thing).
Do you change the transmission oil annually? - I am WAY behind on this, but I'll start doing it every year per Jesse's note.
Empty the seawater strainer? - I make sure this has pink antifreeze in it for the winter, then I clean it out at the start of the season.
Close seacocks for the seasons after draining them? - I usually close them, but I'm probably not consistent.

I also send pink antifreeze down every sink, drain, etc. that is connected to a through hull and I work the lever as the antifreeze drains out...somewhere I read about water getting trapped in the ball and cracking over the winter so I do that now. I know you were specifically talking about the engine, but I thought I'd throw that in there.

The only other item I'll note is that I have never sent 5 gallons of pink antifreeze through the engine...I do 2 gallons. I also disconnect at the pump and attach a hose there to draw in the antifreeze, and then I pour antifreeze down the intake line, into the seawater strainer, and out the through hull (and that is in addition to my 2 gallons through the engine). Now I'll sit back while everyone tells me why I should be doing 5...
 
Oct 3, 2011
735
Anam Cara Catalina 310 Hull #155 155 Lake Erie/Catawba Island
Do Not Forget the stern shower and shower sump in the head . I am in fresh water also, leave the impellar in, but we watch the hours on it, Change the oil every year prior to haul out and fuel filters based on hours or what our plans are for the coming sailing season in the spring!
 
Apr 19, 2020
20
Catalina 310 Kenosha, WI
The only other item I'll note is that I have never sent 5 gallons of pink antifreeze through the engine...I do 2 gallons.
Good to know. I only suggested 5 gallons as I didn't know how much I would need and didn't want to be in a situation where I ran out before I was done. I'll keep an eye on what gets squirted out with a gutter section and also check the quality of it with refractometer.

It wasn't mentioned by anyone, but I'm also thinking of sending an oil sample in for analysis every couple of years (especially in the first year of ownership). Good to plan that before you recycle your used oil.

thanks again!
 
Feb 8, 2014
1,232
Columbia 36 Muskegon
I agree with everything that @TomJ wrote except for the transmission fluid. I changed that every year based on Mainesail's recommendation.
Assuming it's the Hurth box, the manual for that recommends filling it to the top with ATF then draining back to normal level in the spring. I doubt many do that but it will prevent corrosion.
 

Tom J

.
Sep 30, 2008
1,670
Catalina 310 Quincy, MA
Assuming it's the Hurth box, the manual for that recommends filling it to the top with ATF then draining back to normal level in the spring. I doubt many do that but it will prevent corrosion.
Sounds good, but I doubt I would remember to drain back to normal level in the spring! Actually, I don't remember ever forgetting anything, but you never know.;)
 
Jul 1, 2010
767
Seaward 25, Catalina 350 Erie, Pa
Don't forget to pump out the holding tank before haul-out!
And depending on the tank drain configuration on the 310 you probably will want to leave the tank drain open for any liquid to escape so the valve doesn't freeze up. On the 350 that's a necessity. (make sure you catch what comes out with a bucket to avoid embarrassment even though you pumped and flushed the tank).
 
Sep 23, 2009
1,406
O'Day 34-At Last Rock Hall, Md
If I remember correctly the raw water cooling system is under 2 gal but I run 4 gal thru it and still check the specfic gravity. Antifreeze is cheap, engines are not so 4 or 5 gal will give you some piece of mind.
After haulout don't forget to disconnect batteries and remove garboard drain plug from keel if your boat has one.
 

Tom J

.
Sep 30, 2008
1,670
Catalina 310 Quincy, MA
And depending on the tank drain configuration on the 310 you probably will want to leave the tank drain open for any liquid to escape so the valve doesn't freeze up. On the 350 that's a necessity. (make sure you catch what comes out with a bucket to avoid embarrassment even though you pumped and flushed the tank).
Good point, but on the C310, the holding tank doesn't have a drain as such. The bottom of the tank feeds to the macerator, which then discharges through a through-hull in the bottom of the hull. I run anti-freeze through the head system before pumpout, then put some anti-freeze in the tank and run that through the macerator after haul out. This keeps the macerator from freezing, and helps to clean out the macerator somewhat.