“EFI” Winterizing Help MerCruiser 350 Mag MPI Horizon

[Luna Sea]

MIE (350 HORIZON MPI 71C BOB FWC)<br />Serial Number: 0L673252 Model Number: 3F4107JM1<br /><br /><br />I need to winterize this Fresh Water Cooled EFI engine ASAP and I have a couple of questions on the following steps from my manual: <br /><br />5)“Flush” the cooling system. <br /><br />7) Remove water separator and replace 2 ounces of gas with 2 ounces of 2-stroke oil. Disconnect the harness from the fuel pump and the fuel boost pump. <br />Start and idle until the filter and the injector system are empty and engine shuts down.<br /><br />10) Drain seawater section of cooling system.<br /><br />Now, I talked to the yard where I’ll be storing and they don’t “drain” engines. I’ve never done that either. I’ve always mixed anti-freeze in a bucket and shoved the seawater intake hose in there and just before the bucket emptied I’d dump Mystery oil down the carb. <br /><br />This is my first EFI and FWC engine, and it’s a beauty, but the budget has me winterizing it myself. Here’s what I plan to do. <br /><br />1) I’m missing the other half of the “flushing” “quick connect” that’s hooks to a hose and plugs in up near the manifold. $50 for the missing piece! If I wasn’t a mooring boat I’d buy it cause I’d use it more than once a season. I plan to “flush” by sticking the seawater intake hose in a bucket and keeping the hose in the bucket and letting the engine run for a spell. Any downside to this?<br /><br />2) Here’s the tricky part, running enough anti-freeze into the engine while using the “2-stroke oil in the water separator” fogging method. Only thought I have, to be safe, is to run anti freeze in there once-3 or 4 gallons. Then add the oil to the water separator and fill the bucket with anti-freeze again? I can see using 10 gallons or so of anti-freeze this way and making a heck of a mess. I’m afraid if I try to do these 2 things together the engine could fog before the anti freeze fills all the voids!<br />And do I need to disconect the fuel harness's? No idea where they are, would turning off valve suffice?<br /><br />Also, on a fresh water cooled system, should the thermostat come out for what I’m doing?<br /><br />Thanks for taking the time to read, have a great “off season”!

 

[Don S]

Re: “EFI” Winterizing Help MerCruiser 350 Mag MPI Horizon

Since this is a bobtail engine package in an older boat, do you have a Alpha or Bravo drive. If an Alpha drive, the raw water pump is in the drive and not engine mounted like the Bravo.<br />That flushing kit is part of the engine package, and according to the information, the flush kit was sent to your dealer.<br />I really never liked running the fuel systems dry. What we have been doing for years with the MPI engines is hooking up a small remote fuel tank to the fuel filter. In the remote tank we have the fogging mixture. We then start the engine and run it on the tank. During the process you can run the antifeeze through your system as the engine is not running out of fuel.<br />Then unhook the remote tank and dump it in the gas tank, a gallon won't hurt a thing.<br />Your thermostat doesn't have to come out on a fresh water cooled engine. Look at your cooling diagrams. The engine block and half the heat exchanger already has antifreeze in it.<br />You also want to run the engine on muffs to start with, and flush any salt water out of the system and get it warmed up for the oil change prior to winter layup.

 

[Luna Sea]

Re: “EFI” Winterizing Help MerCruiser 350 Mag MPI Horizon

Don,<br /><br />First off, thanks for your reply.<br /><br />My "unique" 25' 1981 Grady White Wahoo is a straight inboard, I guess I left that out! So my intake hose is a simple ball valve connection.<br /><br />The remote tank sounds like a good idea. I found a site yesterday that suggested a "special blend" of 50% gas, 35% 2 cycle oil, 5 % fuel stabilizer, 5% alcohol or dry gas, and 5% fuel system cleaner (or fuel injector cleaner). I just didn't put 2 and 2 together, maybe I can temporarily plumb in a remote tank to my system!<br /><br />Here's the related "winterizing" link if anyones interested.<br /><br /> <br /> boatfix winterizing link

 

[garycinn]

Re: “EFI” Winterizing Help MerCruiser 350 Mag MPI Horizon

Crazyman, er, Luna Sea:<br /><br />Don is right, Merc doesn't want you to run it dry like they used to tell you to do in the Merc manuals.<br /><br />Use the separate tank. Here is the exact blend from Merc. Don't mix 6 gallons. The mix is a 10:1 ratio of 2-cycle oil to gas. Mix as much gas as you will need and dump the remainder in the tank.<br /><br /> http://www.boatfix.com/merc/Bullet/01/01_15.pdf

 

[Luna Sea]

Re: “EFI” Winterizing Help MerCruiser 350 Mag MPI Horizon

garycinn,<br /><br />A+++ for that attachment buddy! I is truly impressed!!! <br /><br />PS My dog's name is Luna. I'm not crazy, really!

 

[Luna Sea]

Re: “EFI” Winterizing Help MerCruiser 350 Mag MPI Horizon

Well, it's winterized! And I see another post or 2 here that could find this relevant, so I'm bumping it up, and thanking those who helped.<br /><br />I did plumb that special 2 stroke,fuel blend (see garycinn's hyperlink) into the fuel line after flushin with fresh water and warming it up for about 20 minutes. <br /><br />I then ran the 2 stroke mix for about 12 minutes before pulling the garden hose out of the 5 gallon bucket I had down in the bilge and dumping in 6 gallons of the -60 degree purple anti-freeze.<br /><br />The bulletin states to run it for 5 minutes at 1300 rpm's, but anything over 1000 and the bucket would empty faster than the hose would fill it! Next year I plan to put a 1 1/4" fitting in the bottom of a big barrel so I can up the rpm's for a while then lower to let the barrell recoup some!<br />And the hose I was using had full city water pressure!<br /><br />Only thing I didn't like about the 10:1 mix was I didn't really see the fogging "smoke" like I used to when I dumped mystery oil down a carb. It was a very windy day so I couldn't determine if there was any white smoke at all.<br /><br />The engine did stall once about halfway through the job when I lowered the rpm's to about 800, it wouldn't normally stall at this rpm so I'm assuming the mix was in my injectors at that point.<br /><br />Thanks again!