Fogging and whether to leave carburetor wet or dry

[mudsnowh2o]

Hello, I am a first time poster but long time lurker here on BITOG. I apologize if this has been discussed before but my searches were not turning up anything. In the manual for winterizing my ’07 Mercruiser 4.3 it is recommended to unhook the fuel line and run the carb dry before storing for the winter. I have been doing this by just unplugging the electric fuel pump and running it dry that way. I am torn on whether running the carb dry is really a good idea or not as it seems this would leave space for condensation (although I am in a dry climate) to take place and let seals dry out. Also it is very hard to time the fogging right so you are getting a good amount of fogging oil down the carb when it is getting ready to run dry.

Seems like it would be better to just treat the fuel, run for a bit, then fog er up. I have also contemplated dumping some 2 stroke or fogging oil in the fuel filter/water separator (how much?), then running it until it starts smoking, then unhook the fuel pump and run it dry.

Anyone have any insight?

Thanks.

 

[440Magnum]

Its a REALLY good idea. Leaving gas in the carb and letting it evaporate from the carb float bowl(s) leaves a nasty, sticky film of additive residue on the bottom of the carb bowls. I've had carb floats stick to the gunk left behind in the past.

Your idea of leaving some oil in the bowls isn't bad. When I know I'm going to park one of the carbureted cars for a long time, I spray a few shots of either Sea Foam, 2-stroke oil, or MMO down the bowl vents so that there's a little oil in the bottom of the carb bowls. It won't evaporate and just mixes with the fuel when I go to start the car up. It even provides a little extra top-end lubrication after a long sit.

 

[The motor guy]

You can't run a carb dry. It's like trying to drain every last drop of oil from your car. Personally I put marine grade stabil in there and then start it up once a month.

 

[mudsnowh2o]

Originally Posted By: motor_oil_madman
You can't run a carb dry. It's like trying to drain every last drop of oil from your car. Personally I put marine grade stabil in there and then start it up once a month.


You are correct since the fuel is not picked up from the bottom surface of the bowl. What I mean by "dry" is running it until it is low enough that the engine dies.

 

[Donald]

I would use a decent stabilizer (marine StaBil or Startron) in the tank. I do that for my 5.7L Merc.

The fogging oil is not for the carb but for the cylinders. I typically warm it up a bit, then I use two cans of fogging oil at once, one down each side of the 4 barrel carb. The goal is to stall it on fogging oil. Some fogging oil comes out faster than others, I forgot what I use. Fogging oil is foamy and contains a tacky component to stick to cylinder walls and not puddle up. Because its foamy, its hard to hydro-lock an engine which you could do if you just poured in liquid oil.

I do the cooling system by pulling select hoses and filling them with AF after draining the block and manifolds. I am not sold on trying to draw in antifreeze via the muffs. Too many things could go wrong.

 

[lars11]

my volvo 5.0Gi recommends to run a gallon of 1:8 fogging oil:fuel and fuel stabilizer through the fuels system at end of season to protect both the fuel delivery system and the internals of the engine.
Could be a solution for your engine too, maybe a gallon is a bit much but the idea could fly I think.

 

[Robenstein]

I always just run a healthy dose of stabil in the gas and shoot some fogging oil in the cylinders. Stored a car for 2 years this way and it fired right up. Without it, I was pulling the 3x2 setup and cleaning carbs after just one winter sitting.

 

[Bluestream]

I would store the carb wet. Do not mix oil in the gas, just fog through the carb until it stalls.

 

[Phishin]

I have never stalled out my boat with fogging oil. I always just remove the plugs, squirt in a bunch of fogging oil, turn over the engine a few times with no spark...and repeat that about 3 times total.

I've never stalled a motor out with fogging oil. Is this a superior technique to what I'm doing?

Oh, and I add a healthy slug of blue Stabil to my fuel and keep the carbs full.

Usually in the spring, I drain the carb bowls with the drain screw, re-tighten, and then fill the carb bowl by squirting a ton of carb cleaner through past the butterflies. Then drain that out through the carb bowl drain screw. Install new plugs, and she's ready to go. I always take a compression reading on each cylinder when I'm installing new plugs. And keep a log of all my values to keep an eye on things.

 

[Boatowner]

I have a 2007 4.3 and I have not had any spring starting trouble once I figured out to loosen the gas cap first. I use a stabilizer on my last day out to make sure it is all through the system. I take the boat home, drain and refill the oil and then run it while squirting fogging oil in the carburetor so the engine starts to stall. I turn it off and run the starter a short while as I spray fogging oil in to finish it off oily. Then I drain the block and call it good.

 

[lars11]

i think the carb set ups are often more prone to gum/dirt problems and also easier to empty than for example the TBI or MPI systems with dual fuel pumps, feedback lines and large pickup boxes that can't be run dry and are not supposed to be dismanteled either (some)
My TBI setup can't be run dry and can't really be taken apart, so that's why volvo says to fill it with fogging oil and stabilizer mixed fuel instead.
So given the fact that it is not to be taken apart and that the oil/stabil mix seem to work for volvo under warranty, it really seem to make sense.
Do this for the carb setup and you should not have to run it dry, spray down the intake, empty bowls and whatever. Just put the fuel line in a can with the conservation fuel, run a quart through and you are done with both the engine and the carbs!!

 

[440Magnum]

Originally Posted By: motor_oil_madman
You can't run a carb dry.



Yes, but when you let a FULL float bowl evaporate dry (which only takes a few weeks), it leaves many, many times the amount of sticky additive deposits in the bottom of the bowl as it does when there are only a few drops to evaporate.

And on Carter carbs or others where the jets are in the very bottom of the float bowls, you CAN run them essentially completely dry. Not with Holleys, though.

 

[440Magnum]

FWIW, Fogging doesn't do a darn thing for the carb itself. Its good for valve stems, rings, etc. but to help the carb you need to spray the oil directly into the float bowls either thru the fuel inlet (difficult) or the vent tubes (super easy with a spray can of MMO or Sea Foam.) Where the vent is located depends on the year and brand of the carb. If you see angle-cut tubes facing upward as you look down the carb throat- those are vent tubes. Carter 4-barrels have vent holes nearly hidden just inside the air cleaner gasket ring. Some have them on top of the float bowls and covered by spring-loaded rubber disk valves that close when you open the throttle. Its worth figuring out where your particular vents are located, and on a boat carb they WILL be somewhere inside the intake plumbing rather than on the top of the carb bowl. No vapors allowed in the engine space!

 

[lars11]

Or, if you run through fogging oil mixed fuel...

 

[friendly_jacek]

LOL, I asked a similar question on a boating forum and got no useful responses. I should have asked here instead.

In the meantime I did my gas experiments clearly showing how gas exposed to elements produce nasty deposits that don't solve in fresh gas anymore.

I decided the best way to prevent carb deposits is to routinely use gas stabilizers, spike the gas in carb bower with TCW3 or fogging oil and run it as dry as possible before storage.

So, I basically agree with 440Magnum on this one, except for using MMO or Seafoam.