Is fogging an MPI engine necessary?

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GripB

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I have twin MerCruiser 6.2L MPI Horizon inboards. The more I read/discuss fogging them, the more I see it not being required. Let me know.

Thx,

Greg
 
The Horizons have the air evac system. I have never fogged mine. I haven't had a problem in the spring to date (knock wood) and last winter was a bear here.

Additionally, according to GVP fogging an engine with iridium plugs destroys the plugs.

I run a double dose of Marine Stabil and MMO added to whatever gas is left in the tanks and purge via the air system. So far so good.
 
David,

I've read the manual and I'm trying to understand the air evac system. Am I correct in thinking that you can either do the air evac or run pink stuff through until you see it coming out the exhaust?

Also, what do you mean by "purge via air system" after running the MMO and Stabil.

Thanks,

Greg
 
If anything, only spray the fogging oil into the cylindar through the spark plug hole, don't spray it into the air intake.

On my outboard, I make a mixture of fuel, Marvel Magic Oil, stabilizer and injector cleaner. I start the engine with this mixture going into it and run it a couple of minutes.
 
I don't fog anymore. Never have a problem
You can fill your fuel filter with half MMO and half fuel and then run engine and run pink stuff in.
I saw my mechanic do that on my mercs a few times, then he stopped and said it wasn't needed.
 
MPI No fogging needed at all.To winterize drain thru one plug on the bottom (blue) and for fast operation remove plug on the top of the engine Run AF(pink) thru.
 
I had 6.0 MPI Horizons and the mercruiser manual said to put 2 oz of 2cycle oil in fuel filter then run the engine till they quit with fuel valves off position.
 
quote:
Originally posted by GripB

David,

I've read the manual and I'm trying to understand the air evac system. Am I correct in thinking that you can either do the air evac or run pink stuff through until you see it coming out the exhaust?

Also, what do you mean by "purge via air system" after running the MMO and Stabil.

Thanks,

Greg

Click to expand...


The manual leaves a lot to be desired.

For the sake of argument, I can carry 100 gallons per side, 200 gallons total fuel capacity in Saint Max. Again for the sake of argument, let's say at the end of the season, my fuel gauges read 1/2 per side = 50 gallons in each tank.

I have two each 5 gallon gas cans. I put The required amount of MMO and Marine Stabil in each 5 gallon gas can to treat 100 gallons (double dose for each tank).

I pour the contents of each 5 gallon gas can, one in each main fuel tank of Saint Max.

I fire up the engines and the gennie.

I go about winterizing the remainder of Saint Max and remove what needs to come home for the winter. All told the time is between 30 and 45 minutes of engine and gennie run time.

I am HOPING the mix got to the engines and gennie. So far, so good for me.

I shut down the engines and the gennie and close the raw water intakes to all machinery.

I remove the drain plug from the gennie muffler.

I use the bicycle pump that is attached to the heat exchanger on each engine and pump the system full of air via a tire air valve device on the top of each engine. The pressure from the tire pump forces raw water valves to open and drains the raw water out of the system and into the bilge. I then turn on the bilge pump and pump all the water that was in the engines over the side. I install, plug in and turn on my Xtreme engine room heater and go home.

The purpose of the air evac system is to eliminate the need for pink. The closed side of your system is as well protected as your vehicle for the winter. The air evac rids the raw water side of the system of the water that could freeze.

I Duck Tape a placard to the dash and to the power panel that reads "All Engines and Generator Winterized. DO NOT START ANY MACHINERY!" That's more a reminder for me in the spring than anything else.

It's a GREAT concept. The first year I had Saint Max, she was at a marina very close to home. It was not uncommon for me to go to her weekly, release the air pressure on the system and fire up the engines just.....because I could! The air evac is a 15 minute evolution for both engines. As much as I dislike Merc engines, my hats off to them for this development.

Let me know if I can be of any help. You are not that far away that if you need me to drive up to show you what I just tried to explain.

HTH
 
I called MerCruiser direct and also an acquaintance service manager regarding fogging my particular engines. They both recommended running a cocktail through the engines (this was in the manual and I totally missed it). It consisted of gasoline, TC-3W 2-cycle oil and Sta-Bil. I disconnected the fuel line and ran an extension into this "cocktail". I then ran each engine for approximately 10 minutes (until I could smell the fogging).

Once I was sure that the fogging had circulated through, I shut off the engines. I closed the seacock’s and disconnected the hose for each engine and genny at the seacock’s. I then connected an extension to a large container of antifreeze. I circulated anti-freeze through each engine and the generator this way. I just poured anti-freeze directly into the heat pump strainer (cap removed and funnel) since I had plenty of access.

I'd like to make or purchase strainer caps with fittings that I could attach my anti-freeze hose directly so I don't have to struggle with the hoses each year.

Greg
 
Does the fogging solution run through the fuel line mess up the plugs?
 
quote:
Originally posted by marsij

Does the fogging solution run through the fuel line mess up the plugs?

Click to expand...
Good question/a question I didn't think about asking. I'm planning on changing plugs in the Spring anyway.
 
I just put in brand new set of platinum plugs this year. I don't want to have to change them.
 
quote:
Originally posted by marsij

I just put in brand new set of platinum plugs this year. I don't want to have to change them.

Click to expand...
I don't blame you $$. I'm going to call MerCruiser today. I'll post my findings.

Greg
 
I spoke to Mercruiser earlier today. The tech rep. said that they've been recommending and putting this fogging "cocktail" in the MPI engine manuals for years. He said that this process has been proven to be the best way to coat the internal engine parts. I expressed my concern about the rich mixture and potential adverse effects on plugs (especially the hi $$ type). He said that they haven't received any negative feedback from a properly mixed/used fogging "cocktail".

Greg
 
Ok, that's good to hear! I'm not so sure Mercruiser has been recommending the cocktail "for years" though. I believe I read (could be wrong) that Volvo Penta recommended the cocktail method & Mercruiser eventually jumped on board because it is supposed to be the best way....I just hope they are correct about the plugs though!!
 
My engines/manual is 8 years old and it has that "cocktail" fuel treatment in the extended storage section, though I'm not sure how many model years prior it's included.

We'll have to see come Spring, marsij.

Greg
 
Holding my breath lol!!. I have a very good marina/service but to save money last year I did everything myself. I winterized/fogged the engines then changed the plugs in the spring (marina did that), my boat ran better this year than it has in years..pretty much since the last time the plugs were changed. I read many people saying they fog with a different set of plugs than they run with, and hardly being a mechanic myself, it does make sense that the oil could/would effect the performance of the plugs. But, I don't have time to do it myself this year..actually not even sure if I will launch my boat in the spring..so just have to keep my fingers crossed.
 
I don't fog my motors. I do put a healthy dose of Stabil in the tanks before the final run so it mixes up and gets through everything. That stabilizes the fuel system.
As far as coating the cylinders with oil, which is what fogging is all about, I suppose if you really feel the need to do it you could just pull your plugs and spray a little fogging oil in to each cylinder, or add Marvel to the gas before your last run and that should put a coat on the cylinders if you don't burn it all off.
 
Merc. Service bulletin No. 2001-15
New Gasoline EFI/MPI Frogging Procedure
6 gal. Container
5 Gal Regular unleaded 87 octane
64 fl oz. Mercury / Quicksilver Premium Plus 2 cycle TC-W3 outboard oil
5 fl oz. Mercury fuel conditioner & stabilizer
run engine at 1300 rpm for 5 - 10 min. DO NOT RUN DRY
I've been using this procedure on my VP 5.7 MPI for 10 year's without a hitch.
 
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