Mercruiser 4.3 MPI Q's

[DcMb]

Hey all,

I'm the new owner of a 2006 Crownline 180 BR with the 4.3 Mercruiser MPI/Alpha Drive engine. I've been looking around for winterizing information for some time and am at the point where I just need to ask. There are enough variables on how to go about winterizing this engine that looking through them all is dizzying!

Regarding draining the engine I see that the single point drain system on these engines is frowned upon and that one should drain from the other manifold locations. My question here is where are all these locations and how many in total are there?

Secondly I would prefer to top load the coolant flush once the engine is drained and not have to screw around with running the engine to pump it in. Is there an upper hose on the engine to simply dump the coolant in from the top and and watch for it to drain pink via the aforementioned drains? If not what tools/parts are required to run the engine and ingest the coolant through the system?

Now onto fogging. Is this really necessary on this fuel injected engine? If so what is the best process for that? Is running stabil through the fuel system not enough? Can any other type of upper cylinder lubricant be used i.e. Lucas?

Lastly I believe the engine is not running properly currently it is sluggish on launch slow to plane and does not hit top RPMs. My father in-law owned the boat before me and he has no clue what has been done to the boat other then paying a local shop to winterize it every year. My top suspect on this particular issue is plugs (which I doubt have ever been changed) and the flame arrestor which again I doubt has ever been serviced/cleaned. I also say something regarding displaced exhaust flaps??? Anything else I should be looking for on this topic?

Thanks all, the newbie appreciates it.

 

[alldodge]

Winterization of signle point drains
https://forums.iboats.com/threads/how-to-winterize-your-motor-without-draining-the-water.702131/

Do not fog a EFI/MPI motor, this will mess up the sensors. Mix fuel with 2 cycle oil on portable tank
https://forums.iboats.com/threads/winterizing-fuel-oil-mix-for-mpis.739115/

Not having a serial number I cannot look up your motor. If you have a flat type distributor cap then I would replace it. The flat caps go out all the time without warning and can look great. Do give it a full tune up

 

[DcMb]

Thanks for the quick response! I'll take a look at the links. It is the "flat" cap where the wires connect to the side. I'll pick one of those up as well.

 

[DcMb]

I'm back... Reading between the lines in that article leaves me with, don't drain anything use a kit like this:

Amazon.com

To pump coolant in and leave it in for winter.

Is that accurate?

 

[alldodge]

I'm back... Reading between the lines in that article leaves me with, don't drain anything use a kit like this:

Amazon.com

To pump coolant in and leave it in for winter.

Is that accurate?

This is were we get into the kinda, sort of, squishy thing

Yes, I'm being evasive and it's an issue between how it should be done as @muc posted, and how so many others actually did

The first link is pump a AF mix thru motor until the entire motor has been filled with the mix, meaning run long enough to open thermostat and flush raw water out

Personally if winterization is done by the owners manual it will work, but most will not follow to the letter. For me I rip all the stuff out of a raw water cooled motor and turn it back into 7 point drain

Once all the water is out, it's winterized but all must be out. If all is out then it will not freeze no matter how cold it gets. As Bondo says "air don't freeze"

 

[Scott Danforth]

The block busting single point drain works only if the boat is operated in a swimming pool (no debris and dirt)

The system starts getting plugged at the lower block drains, it spreads to the drain manifold and the block never drains

 

[DcMb]

Regarding @alldodge's response. I appreciate the candid response and I now realize why I've been having such a hard time nailing down the winterizing method. This topic appears to be similar to the infamous "which oil is best" threads. There is no single answer and everyone has their preferences. Purists say do it by the manual, shop guys who do it in bulk say "I ain't got time to pull 5 plugs and wait for the drain on 50 boats that I need to finish!"

Regarding Scott's reply, yep makes total sense and this boat has been operated in a small soupy sediment rich lake in Minocqua Wisconsin for it's entire life. Visibility = ~1". It will now be in much clearer Door County Lake Michigan waters.

 

[Scott Danforth]

depends..... sometimes you can see 40 feet down just outside the channel past the door county light house, sometimes you cant see more than 2 feet.

plenty of sediment in lake michigan, especially if you run in the channels in spring

Just dont hit the big rock in sand bay.... BTDT, bought a set of props because of it.

 

[Scott06]

Regarding @alldodge's response. I appreciate the candid response and I now realize why I've been having such a hard time nailing down the winterizing method. This topic appears to be similar to the infamous "which oil is best" threads. There is no single answer and everyone has their preferences. Purists say do it by the manual, shop guys who do it in bulk say "I ain't got time to pull 5 plugs and wait for the drain on 50 boats that I need to finish!"

Regarding Scott's reply, yep makes total sense and this boat has been operated in a small soupy sediment rich lake in Minocqua Wisconsin for it's entire life. Visibility = ~1". It will now be in much clearer Door County Lake Michigan waters.

you will get more clarity in the oil threads... bottom line find a system that works for you and your boat. if its easy to drain drain it, if you reply on AF need to use a big system so it can get up to temp and make sure the freeze point works. Both ways get to the same place depends on the situation.

On my 21 ft BR the 5 plugs are easy to get to so I just replace the plastic plugs every couple years. You can see exactly what's coming out of each drain point and probe them

 

[Scott Danforth]

On my 21 ft BR the 5 plugs are easy to get to so I just replace the plastic plugs every couple years. You can see exactly what's coming out of each drain point and probe them

they make stainless plugs to replace the plastic ones

 

[Scott06]

they make stainless plugs to replace the plastic ones

Yeah I know but stainless can gall and the plastic ones work just fine from my perspective. They seem to bother folks but they work for me.

 

[DcMb]

depends..... sometimes you can see 40 feet down just outside the channel past the door county light house, sometimes you cant see more than 2 feet.

plenty of sediment in lake michigan, especially if you run in the channels in spring

Just dont hit the big rock in sand bay.... BTDT, bought a set of props because of it.

It's been pretty damn clear in recent years which is lovely. Diamond lake in Minocqua is always ~1" vis.

 

[Lou C]

I have a relative that has a 2020 Merc 4.5 V6 with this system, it is used in salt water. What I told him was this, when it's still new and actually drains, you should measure how much drains so you can tell when it's starting to clog. Start with the plug in, let it drain in the bilge, then put a bucket (at least 5 gallon) under the garboard drain and drain the contents of the bilge into the bucket. I know from experience it takes about 4 gallons of antifreeze to totally fill up my old OMC 4.3 V6, block, manifolds and raw water hose.
When the time comes that it doesn't drain you will have to rod out the block drains, and manifold drains, and any coolers like the fuel cooler or P/S cooler. Personally I don't like these systems, they exist because people want the lowest price, (don't want to pay extra for closed cooling which is the best system) and hate dealing with the old school block drains which on many engines are nearly impossible to reach without pulling out seats.
Now, a better system would have been to simply replace the block fittings with a brass threaded fitting with a barbed nipple on the end to extend the drain with a length of hose you can reach, this could still be rodded out with a coat hanger wire if needed, but would be much easier to deal with. This is an easier drain system that would be easy to clean out, unlike Merc's system with miles of hoses and multiple plastic fittings. The manifold drains are normally not that hard to get at.
If I ever find the right fittings, I am going to do that to my 4.3. It would be nice not to have to pull the dang seats out just to winterize it.

 

[DcMb]

you will get more clarity in the oil threads... bottom line find a system that works for you and your boat. if its easy to drain drain it, if you reply on AF need to use a big system so it can get up to temp and make sure the freeze point works. Both ways get to the same place depends on the situation.

On my 21 ft BR the 5 plugs are easy to get to so I just replace the plastic plugs every couple years. You can see exactly what's coming out of each drain point and probe them

hahaha! That's saying a lot. The way I look at it, either way it's probably best to flush coolant through it so doing it with the kit = 2 birds 1 stone. We'll see how I'm feeling once I get in there and how much I struggle to find all 5(?) drain ports? Assuming two down low on each side and then the single point at that back.

 

[Scott Danforth]

the idiot at Mercruiser that thought that little hand-pump would blow debris out of the system never had to pull a drain plug on a shop compressor that only had 1/16" of rust sediment on the bottom and it shows.

if 5hp and 150 psi cant clear a 1/4" NPT port with only 1/16" of sediment on my shop compressor.......no way that little hand-held plastic hand-pump will clear out 6# of debris from the bottom of the block, the block drain hoses, and the drain manifold.

I have pics of my buddys junk block in his 2004 searay from a plugged single point drain system, including the debris we did pull from the block and drain hoses.

 

[Lou C]

What it takes to keep those block drains clear is a set of picks with different angles that enables you to dig out rust & sand that accumulates in the cooling passages at the bottom of the block. This is why I feel all cast iron inboards should be closed cooled: because of how cast iron corrodes…it flakes off more or less chronically and will never stop, so those drains are destined to clog sooner or later.

 

[Scott06]

hahaha! That's saying a lot. The way I look at it, either way it's probably best to flush coolant through it so doing it with the kit = 2 birds 1 stone. We'll see how I'm feeling once I get in there and how much I struggle to find all 5(?) drain ports? Assuming two down low on each side and then the single point at that back.

yes just read what MUC wrote about the flush kit where the 5 gallon one falls short is time to run the engine and recirculate the AF so passages get fully turned over to AF vs mix of AF and water. Thats why marinas use a huge amount of AF that is the expensive PG type with corrosion inhibitor. With a big catch pan it can recirc for long time to ensure it is open.

the 5 drain ports are the exhaust manifolds, both sides of block along oil pan rail, and the big U hose on the circ pump on the block. they all come together at the ball shaped t in water line with single point drain.

 

[Scott Danforth]

Secondly I would prefer to top load the coolant flush once the engine is drained and not have to screw around with running the engine to pump it in. Is there an upper hose on the engine to simply dump the coolant in from the top and and watch for it to drain pink via the aforementioned drains?

to answer this question. Mercruiser used to have in the manual

"optional: after draining, to add antifreeze, remove the thermostat and fill the system with a funnel" or something to that effect.

 

[Scott06]

to answer this question. Mercruiser used to have in the manual

"optional: after draining, to add antifreeze, remove the thermostat and fill the system with a funnel" or something to that effect.

I have used a J shaped piece of old radiator hose -to do so take off the supply hose from OD which is likely on RH side of thermo housing put the J on there and fill with AF

 

[Lou C]

All you have to do is disconnect the J shaped hose at the stat housing & fill it with AF till it spurts out of the stat housing. No need to remove stat housing at all.