89’ OMC 4.3L Winterize Question

[Seaswirl89]

Going to be getting in the mid to upper 20’s next week so need to get my 89’ OMC cobra 4.3 Winterized.
After reading a lot of forums, it looks like I need to remove the 4 brass petcocks, poke them with a wire to make sure they drain, remove the raw water hose and point it down to the hull, remove the large hose at the water pump and drain it, remove the hoses from the exhaust manifolds and let them drain and remove 3 drain screws in the out drive.

I would also like to add antifreeze into the engine and then drain it to make sure I don’t crack my block due to not draining 100% of the water. The camco antifreeze tub system seems easy but how do I know the antifreeze will get past the thermostat and throughout the engine?? Boat runs around 150-160 on the lake but on ear muffs it will run around 120. Assuming it’s a 160 thermostat, I don’t think the thermostat would be open and allow antifreeze into the block while running on ear muffs?

 

[Chris1956]

The best way is to pour the A-F into each of the hoses and watch for it to push the water out. You do not need to run the motor, with this method.

I used to then reinstall the drain plugs and fill the block with straight A-F.

 

[Lou C]

Yep don’t use the winterizing tank they are only good for closed cooled engines. Just drain poke all the holes and that will do it. Adding AF can be done but has to be done the right way.

 

[Scott Danforth]

The camco antifreeze tub system seems easy but how do I know the antifreeze will get past the thermostat and throughout the engine??

easy answer, it doesnt. it appears that you have a rudimentary understanding of how a wax pellet thermostat works and have come to a similar conclusion on your own.

usually the only thing that get AF is the exhaust manifolds as the thermostat never opens

drain everything like you described
then if you want to add antifreze, as per the manual, pour it in with a funnel at the thermostat housing

the only way sucking AF up into an engine can work. you have a heat exchanged cooled motor like Lou mentioned and you use a pump to force it into the muffs

or you get about 4000 gallons of AF (yes, you read that correctly), you back the whole boat into it (to submerge the raw water pump enough to get it to prime), and then you run the boat for about a half an hour to make sure that the motor comes up to operating temperature, then run it for an additional 15 minutes to make sure that the thermostat has opened a few times.

 

[Seaswirl89]

Thanks all for confirming my assumption. I’m glad I asked before I bought the camco tub system. From what I can gather, using that camco system only gets AF into the raw water impeller and into the exhaust manifolds and out the exhaust location on the outdrive, not into the block correct?

 

[Lou C]

Thanks all for confirming my assumption. I’m glad I asked before I bought the camco tub system. From what I can gather, using that camco system only gets AF into the raw water impeller and into the exhaust manifolds and out the exhaust location on the outdrive, not into the block correct?

correct because the thermostat most likely will not open far enough to allow all the raw water (approx 4 gallons) in the block to exit.
the other issue with these kits is they can damage the impeller because the AF is fed via gravity flow, not pressurized like with muffs.
the way I do it on my 88 Cobra:
drain block from plugs poke holes and disconnect big hose at the circulation pump
drain manifolds, poke holes, put a plastic bag over the starter because on those one piece manifolds, the drain will dump water right on the starter
disconnect raw water intake hose at stat housing, point down in bilge to drain
Next....
put OMC gasket sealer on block and manifold drain plugs, replace plugs
re-connect big hose at circulation pump. Disconnect it at the top by the stat housing. Put a funnel in it and fill the engine with Marine AF till it spurts from the neck of the stat housing. No need to remove stat housing, works fine this way. Reconnect that hose.
Now disconnect manifold feed hoses at stat housing, fill each with AF till it runs out of the exhaust housing on the transom, then re-connect those hoses.
Next with the outdrive down, fill the raw water intake hose with AF till it runs out the outdrive water intakes. Then reconnect that hose. There is a drain on the pivot housing on the port side, remove that, a bit of water might come out followed by AF. This prevents the plastic fitting in there from cracking.
On the other side of the pivot housing are 2 drain plugs, top is a vent, bottom is a drain for the pivot housing where the shifter bell crank lives. Water can get in that space and crack the housing if it doesn't drain so remove those too. Use OMC gasket sealer or Merc Perfect seal on all drain plug threads.
About antifreeze, I do not use the -50 or -60 because it gets firm at a few degrees above zero and I don't want that in a cast iron engine, its ok for PVC pipe but not cast iron. I use either -100 marine AF or I mix up a batch of Sierra PG antifreeze (no tox) 50/50 with water. This gives an actual freeze (not burst) protection of -26*, you can go with higher %age of AF if it gets super cold where you are.
Many people in fresh water areas where corrosion is not a big concern do not use AF, they just drain which is fine too. I add AF due to 100% salt water use. It has made the engine last longer in my opinion.

 

[Seaswirl89]

correct because the thermostat most likely will not open far enough to allow all the raw water (approx 4 gallons) in the block to exit.
the other issue with these kits is they can damage the impeller because the AF is fed via gravity flow, not pressurized like with muffs.
the way I do it on my 88 Cobra:
drain block from plugs poke holes and disconnect big hose at the circulation pump
drain manifolds, poke holes, put a plastic bag over the starter because on those one piece manifolds, the drain will dump water right on the starter
disconnect raw water intake hose at stat housing, point down in bilge to drain
Next....
put OMC gasket sealer on block and manifold drain plugs, replace plugs
re-connect big hose at circulation pump. Disconnect it at the top by the stat housing. Put a funnel in it and fill the engine with Marine AF till it spurts from the neck of the stat housing. No need to remove stat housing, works fine this way. Reconnect that hose.
Now disconnect manifold feed hoses at stat housing, fill each with AF till it runs out of the exhaust housing on the transom, then re-connect those hoses.
Next with the outdrive down, fill the raw water intake hose with AF till it runs out the outdrive water intakes. Then reconnect that hose. There is a drain on the pivot housing on the port side, remove that, a bit of water might come out followed by AF. This prevents the plastic fitting in there from cracking.
On the other side of the pivot housing are 2 drain plugs, top is a vent, bottom is a drain for the pivot housing where the shifter bell crank lives. Water can get in that space and crack the housing if it doesn't drain so remove those too. Use OMC gasket sealer or Merc Perfect seal on all drain plug threads.
About antifreeze, I do not use the -50 or -60 because it gets firm at a few degrees above zero and I don't want that in a cast iron engine, its ok for PVC pipe but not cast iron. I use either -100 marine AF or I mix up a batch of Sierra PG antifreeze (no tox) 50/50 with water. This gives an actual freeze (not burst) protection of -26*, you can go with higher %age of AF if it gets super cold where you are.
Many people in fresh water areas where corrosion is not a big concern do not use AF, they just drain which is fine too. I add AF due to 100% salt water use. It has made the engine last longer in my opinion.

Thank you for the detailed right up! I followed along each step in my head and believe I’m ready to winterize the boat. One question in regards to the AF, I can find cheap -50 burst AF locally and my thought was that I would drain all the water out, then refill the engine/cooling system with AF like you detailed above, and then drain the AF out. Reason for adding the AF and then draining it is so the cheap -50 burst AF doesn’t freeze and so any spots within the cooling system that won’t drain out, are diluted with AF and shouldn’t freeze and break something. But that’s likely over kill as the original owner never added AF, he just drained it

 

[Chris1956]

Gee, I bought 4 Gallons of automotive A-F and poured it in after draining the block and manifolds and left it over the winter. In the spring, I drained and saved it for the following winter.

 

[Lou C]

Well I'd just return the AF if you can. Not worth the bother and mess if you are not leaving it in. How cold does it get where you are? If below zero I'd use only -100 or Mix up a batch of Sierra like I do. The problem with these is that -50 or -60 is burst temp of a copper pipe, but I don't want something that gets hard in a cast iron engine at zero. I put a gallon of that stuff in my freezer and that's what happened. So that's why I won't use it.

The problem with automotive (ethylene glycol) antifreeze is that it's highly toxic to humans and pets. So not really a good thing to use for boats where it always gets spilled or drained out.
the only place it should be used is in a closed cooling system (heat exchanger).

merc had this in their manuals but I'll repeat it for understanding:
for freeze protection we DRAIN PROPERLY
for corrosion protection we add antifreeze (I'd add to that proper antifreeze). Merc does not recommend the use of -50 or -60 for winterizing as far as I know.
Note: they are NOT saying, we use AF for freeze protection!
I feel sorry for all the poor souls who use those Camco winterizing tanks thinking they are doing the right thing. They are NOT, because they do not understand how raw water cooling works.

 

[Seaswirl89]

Well I'd just return the AF if you can. Not worth the bother and mess if you are not leaving it in. How cold does it get where you are? If below zero I'd use only -100 or Mix up a batch of Sierra like I do. The problem with these is that -50 or -60 is burst temp of a copper pipe, but I don't want something that gets hard in a cast iron engine at zero. I put a gallon of that stuff in my freezer and that's what happened. So that's why I won't use it.

The problem with automotive (ethylene glycol) antifreeze is that it's highly toxic to humans and pets. So not really a good thing to use for boats where it always gets spilled or drained out.
the only place it should be used is in a closed cooling system (heat exchanger).

merc had this in their manuals but I'll repeat it for understanding:
for freeze protection we DRAIN PROPERLY
for corrosion protection we add antifreeze (I'd add to that proper antifreeze). Merc does not recommend the use of -50 or -60 for winterizing as far as I know.
Note: they are NOT saying, we use AF for freeze protection!
I feel sorry for all the poor souls who use those Camco winterizing tanks thinking they are doing the right thing. They are NOT, because they do not understand how raw water cooling works.

It will get get into the negatives at times where I’m at. Sounds like the best plan may be to just drain it like the originally owner and not use any AF. Still just a little nervous because I don’t know of a way to make sure I drained all of the water out of the system before putting it away for the winter

Or at least for now I will drain the cooling because this weekend the low is suppose to be in the upper 20’s at night (gets up to 50-70 degrees during the day)

 

[briangcc]

Think of it this way.....air don't freeze...

I live in NY where temps can get into the - range fairly easily. Have the marina winterize it every year and it doesn't involve adding any AF to the engine.

 

[Starcraft5834]

Drain all the water out and leave it empty. Air don't freeze i had a 3.0 before, drained it. went through brutal winters -0.. lots of nights, spring. was fine.. fires right up

 

[Seaswirl89]

Think of it this way.....air don't freeze...

I live in NY where temps can get into the - range fairly easily. Have the marina winterize it every year and it doesn't involve adding any AF to the engine.

I agree, air doesn’t freeze. It’s just that this is the first year with the boat and I’m slightly concerned about there being a little bit of water left in the cooling system after I drain in. The thought was to add some of that cheap marine -50 AF, to dilute any potential leftover water and then drain it out as soon as the cooling system is full with AF. It would be essentially like throwing away the AF but would give me some peace of mind knowing that I diluted whatever water I couldn’t get out of the motor. Thoughts? Maybe I’m over thinking and it and following the above draining procedure (4 petcocks, take off large water hose at water circulation pump, take off raw water pump and point down to the hull, drain water lines that run to the manifold, 3 plugs on the outdrive) will eliminate 100% of water in the engine…

on a side note, I just found Prestonstone waterline -100 burst AF locally for $7. Bought a few gallons

 

[Lou C]

You have to remember that water causes freeze damage when there isn’t room for it to expand. So even if there’s a little left in there it will cause no harm. You should get a lot out of the engine (3.5-4.0 gallons) and out of each exhaust manifold (1/2-3/4 gallon or so). Not much out of the raw water intake hose. If that fitting on the port side of the pivot housing does not drain (possible on an old boat) then for sure with the drive down dump some -100 in the raw water intake hose till it runs out the drive water intakes. This protects the p/s cooler as well.

 

[Seaswirl89]

You have to remember that water causes freeze damage when there isn’t room for it to expand. So even if there’s a little left in there it will cause no harm. You should get a lot out of the engine (3.5-4.0 gallons) and out of each exhaust manifold (1/2-3/4 gallon or so). Not much out of the raw water intake hose. If that fitting on the port side of the pivot housing does not drain (possible on an old boat) then for sure with the drive down dump some -100 in the raw water intake hose till it runs out the drive water intakes. This protects the p/s cooler as well.

Thanks for your help! I got it done this weekend. - Outboard drive oil changed
- Engine oil and oil filter replaced
- Drained the 4 petcocks, poking them frequently and let them drain (not sure if was 3.5-4 gallen but somewhere around 2-3 gallons came out)
- Pulled raw water hose off of thermostat housing and pointed it down to drain
- Pulled large hose off at water circulation pump and drained it.
- Removed the 3 drain screws in the outdrive, water only came out of one, other two were dry.
- Put hoses back on, screwed petcocks back in, put outdrive screws back in, put -100 RV AF into the raw water until it came out the out drive(had to pressurize the hose with my mouth to force AF out the outdrive intake holes).
- Poured AF into each other exhaust manifold via the hoses and then drained the AF out via the two petcocks. Left percocks open
- Poured AF into the large hose that lead to the water pump and filled the block up with 1.5 gallons of AF. Then drained the AF out of the block via the petcocks and then took the large hose off at the water circulation pump.
- With all 4 petcocks open, the large hose off at the point where it meets the water circulation pump and the raw water pump house pointed the the hull, I raised and lowered the tongue of the boat from max to min several times to ensure water wasn’t being hung up in some spots

I think I got everything taken care off, only other thing I may do is take the water pump on the cobra outdrive off the let any remaining water out of the water pump housing

 

[Lou C]

When I do it I leave the AF in, that’s for corrosion protection because it keeps air out. Once you drain all the water out and fill with AF no need to drain the AF.

 

[Seaswirl89]

When I do it I leave the AF in, that’s for corrosion protection because it keeps air out. Once you drain all the water out and fill with AF no need to drain the AF.

Good point… there is a fair amount of corrosion in there from the previous owner simply draining the water and leaving it empty.
Also forgot to say I fogged the engine. Engine runs wel but that fighter killed it much quicker than anticipated (1-2 seconds of spraying killed it)