Spring Commmissioning - sparkplugs fouled?

[KeithD]

Hi,
After the engines are recomissioned, is it normal for the sparkplugs to be fouled and need claening or replacement? Or will the excess fogging oil eventually burn off?

 

[ghuskin]

KeithD,

Yes. Typically you'd use the plugs from last year to fire her up and burn all that gunk out of your engine/cylinders. After that you should replace with fresh spark plugs to start the season. At least that is what I do with my boat, as well as my dad's boat with an outboard.

 

[fc3]

I hope you don't have EFI engines, as they should no be fogged. I found that the fogging oil burns off the plugs after the first good run of the season. My previous boat would go a few seasons between plug changes.

 

[Nehalennia]

350Mags are MPI i believe.

 

[fc3]

I had been led to believe that the problem with fogging EFI engines was the GM used floor jets, which would clog with fogging oil. Since I have taken the intake off one of my 7.4s, I see why you can't fog these engines. The fuel injector does indeed face down towards the intake valve as one would expect. The injector and it's pintle are quite well protected. The intake passages winds up and down to provide a tuned length runner. When you fog one of these engines, you'll end up with a gooey mess that you can't clean out without disassembling the manifold. Also because of the way the runners loop, it is very unlikely much of the oil would reach the intake port, which leaves most of it sitting on the bottom of the plenum.

Unlike carbureted engines, no fuel runs though the intake manifold of an EFI engine. It's the fuel that washes the oil from the manifold. I suppose you could use a spray cleaner, but you would need a lot of it. Just for fun, spray a piece of metal with fogging oil and let it dry for a few months. Then try to remove it. It's not very easy, especially where it runs into puddles.

Best regards,
Frank

 

[KeithD]

According to my service writer, the engines were fogged as part of the winterization. I'm checking the boat out tomorrow to see how it's running, and see what steps I may have to take regarding spark plugs, etc...

 

[nyminute]

OK MPI-EFI. I have 7.4's MPI, Do I fog this?