Winterizing Mercruiser 4.5 250hp

Phil Chieco

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Does anyone have clear instructions on how to winterize the new Mercruiser 4.5 250hp engine as well as if I can use alternative engine oil(s) and oil filter(s). Thank you
 

LouC

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I can't say on the actual winterizing procedure but if its under warrantee, I'd for sure use the Merc 25/40 syn blend and filter, as well as the their High Performance gear lube. You're not saving much by using other stuff not approved by them.
 

Phil Chieco

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I can't say on the actual winterizing procedure but if its under warrantee, I'd for sure use the Merc 25/40 syn blend and filter, as well as the their High Performance gear lube. You're not saving much by using other stuff not approved by them.
Yes definitely. Just asking if I was in a pinch.
 

cwms

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Is the engine FWC or RWC? Also, where are you located? Frozen Canada or fair weather S. Carolina?
 

cwms

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I do it the quick and easy way and has never failed me. I have a bucket with a faucet, sit it on the swim platform with a short hose going to ear muffs. Since you never know for sure if the T-stat is either opened or closed, I remove it…only takes a few minutes. Start up the engine with 3-4 gallons of pink. Where you are, I’d probably go with 4-5 gallons. When the bucket is empty, shut off the engine. No bucket…stick a funnel in the end of the hose.
I get my pink from West Marine, not the RV water system stuff, but the pink made to run thru engines. Costs just a little more but does have rust inhibitors in it.
 

ddurand

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Many people do as cwms suggested. Just be sure the thermostat is open when you are doing it. Some run on a garden hose for 15 minutes to warm the engine up then switch to the pink antifreeze. The antifreeze made to winterize engines is better but I'll be many many boaters use the pink RV stuff from Walmart and it works just fine.

I prefer to drain the block by finding and opening the drain petcocks (poke a nail in to dislodge rust). Then pull the main hose going to the water pump from the lower engine and fill the block with antifreeze. Same for hose going to outdrive. Drain the exhaust manifolds by opening a drain plug or pulling the hose. Pour some antifreeze through the hose going to the risers.

If you have a hot water heater you need to pull a hose and blow out any water in it while the engine is being drained before you add pink antifreeze.

You could ask a marine mechanic to show you the location of the proper hoses and drain plugs.
 

cwms

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Many people do as cwms suggested. Just be sure the thermostat is open when you are doing it. Some run on a garden hose for 15 minutes to warm the engine up then switch to the pink antifreeze.

that’s why I remove the T-stat. Only takes a few minutes and any doubt (is it open or closed) is removed.
While you are still draining petcocks and pulling hoses, I’m finished and putting the boat away.
 

alk

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Do you have, or can you get, the owners manual for this motor? Does Seloc have an aftermarket manual Yet? These motors are a bit more complex, as compared to the older ‘pull the thermostat /drain the block’ that most of us are used to. For example, looking briefly at the merc website, noticed the text below. I would want to know more about these features before attempting a diy winterization.


Water drain system
  • Air Actuated "Season Extender" (Bravo)
  • Easy Drain "Season Extender" (Alpha)
 

cwms

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alk makes a good point. I’ve never had any of these new fangled engines…always had old school.
 

ddurand

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One of the reasons I like the idea of draining the block and refilling with antifreeze is I could prior to that focus on stalling the engine using 1 or two cans of fogging oil into the carb.

But newer engines are EFI and now its recommended to switch the fuel line into a container of gas, stabilizer and 2 cycle oil (I think thats it).
 

LouC

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Yep I'd want to make sure that the single point drain, is actually for winterizing not just extending the season use (I recall reading something about this in some of Merc's literature). In fresh water these systems may work OK but in salt, with a cast iron block/heads (which the Merc 4.5 has, just like the older style GM marine engines) rust flakes can clog the drain holes/hoses and then you have a big problem with trapped water that can expand and crack the block & heads. Here in salt people take them off and use conventional drains.
When I do mine, I drain manually, poke the holes, then put a bit of OMC gasket sealer or Permatex aviation on the plug and re-install. I fill the engine and manifolds manually with either -100 Marine AF or I mix up a batch of Sierra PG antifreeze 50/50 with water. What I do is after disconnecting the bottom of the big hose at the circulating pump and draining the block drains, I reconnect that bottom end of the hose and disconnect the top end at the thermostat housing. Then replace the drain plugs. Next I put a funnel in the top end of that big hose and fill the engine manually with AF till it spurts out the thermostat housing neck. No need to remove the housing it works fine that way. Then reconnect that hose , engine is full. After draining the manifolds by removing the plug and probing the holes then replace the plugs with a bit of gasket sealer on the threads. Next, I fill the manifolds by disconnecting the manifold feed hoses at the stat housing, till some AF runs out the exhaust housing on the transom mount, then reconnect the hoses. Lastly with the outdrive down, I disconnect the raw water intake hose, at the stat housing and hold it down so it drains, then hold it up and fill with AF till it runs out the outdrive water intakes. Reconnect and you're done. Works 100% no risk of trapped water.
 

LouC

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PS, a family member has a 2020 boat with the new Merc 4.5 V6. It runs great, starts easy, but BOY is it complex, and the engine acccess is not too good. You can do oil changes and reach the easy drain plugs on that plastic manifold, but if you had to change a starter, I can't imagine it would be easy. On my old boat I just move the rear seats out of the way and its wide open. Some of the newer design I/O boats, especially smaller ones (under 25') have no room at all for access. They have these silly folding seat walk throughs that take away 1/4 the width of the engine compartment.
 

cwms

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One of the reasons I like the idea of draining the block and refilling with antifreeze is I could prior to that focus on stalling the engine using 1 or two cans of fogging oil into the carb.

But newer engines are EFI and now its recommended to switch the fuel line into a container of gas, stabilizer and 2 cycle oil (I think thats it).
The last carborated boat I had…I was pouring AF into my strainer with the engine running, and as I was getting close to finishing, I had a buddy spray fog into the carb. Killed 2 birds with one stone.
 

sugilbert

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The last carborated boat I had…I was pouring AF into my strainer with the engine running, and as I was getting close to finishing, I had a buddy spray fog into the carb. Killed 2 birds with one stone.
Each of my 2bbl 4.3 Mercs needed 2 cans simultaneously sprayed to kill the engine.
 

Bt Doctur

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