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Not sure if anyone has done a SeaFoam treatment write-up. Keep in mind, I wrote this back when I was doing Tercel 3AC engines. The concepts should be the same though.

I figured I'd post on one of the most effective fuel/crankcase additives sold main-stream.

The mose widely recommended way to use Sea-Foam that I have heard for the application of cleaning out your crankcase (where the oil goes) is as follows.
When the oil is low enough, by means of draining, when the oil is consumed by the engine, or on a fillup of a cheap temporary oil, pour an entire can into the crankcase. Depending on how willing your are to face the risk of clearing out hole-clogging sediments (meaning sediments blocking off leakages from the engine) then you can either run the engine for about 20 minutes, revving every so often, then draining, to driving around normally for around 50 miles then changing.
BENEFITS- As I have been told, the benefits of this treatment come in the form of smoother operation due to removal of imposing sediments (Gooey gunk) that may slow or make the moving parts of the engine have more resistance. Cleaning the PCV valve out partially from the evaporating vapors of the Sea-Foam moving through it. This can improve mileage and running efficiency. Some say that it can help create a better seal of the rings to the cylinder wall.
NEGATIVES- As far as I have heard, the primary concern is cleaning out sediments that were blocking holes in seals or gaskets where the oil could leak out. It is also said that sometimes deposits can build up in wear-gaps in part of the engine, and that removing them may cause rattling. I doubt that part personally.

There are several ways to execute this. They can depend on just how serious your symptoms are and whether you have Injection or Carb.
The universal treatment, which works on diesels, 2-strokes, carbed gassers, injected gassers, etc is as follows.
Go buy 2 cans (or enough for 2 strong tanks of treatment, 2 cans is good for a 13 gal tank) of Sea-Foam in the pour can. Run your tank as near to empty as you are comfortable doing, then pour in ONE can (or 1 strong tanks worth) into the tank then before driving, top off with Midgrade or Premium gas. Drive your car, again, to near empty. Repeat. After 2 tanks of this, your fuel system and engine will be a good deal cleaner.
BENEFITS- Potential smoother running, potential "pinging" solution, potential fuel economy improvement, potential power increase.

NEGATIVES- Apparently some people are concerned about the effect on your spark plugs. I, personally, have seen no detriment through the 5 times I've done this in my car to the 3 times its been done in our 5.7L TBI V-8 MerCruiser Marine engine. Some people are also concerned with the effect on older systems natural rubber componants. I have no evidence to prove or disprove that Sea-Foam effects natural rubber.

Buy a can of B-12 Chemtool Carb Cleaner or Deep-Creep (Sea-Foam in aerosol form) <I've used both and they both work great> and 2 tanks worth of Sea-Foam. Apply the first tanks worth as detailed above. Drive home. With the engine running, spray the cleaner into both barrels. DON'T kill the engine at this point. If need be, use the throttle control on the back of the carb (for our application). Use short controlled bursts. After a bit of using this, bog the engine then kill it by spraying heavily into the barrels. Allow the vehicle to sit for approx. 30 minutes. Fire her up and drive her hard for a mile or two. When you get back home, repeat the above process, only this time, a few things are added. After the engine is killed, spray a heavy dose into both barrels. Now, do you see the vent tubes over each barrel? (B-12 works better for this part btw) Plug one with your finger then spray heavily down the other. Do the same on the other side. Repeat this part twice. (OPTIONAL) Remove the spark plugs and spray a fairly light dose of cleaner into the cylinder. The point here is not to fill the cylinder with cleaner, just to get a very light but even coat on the walls.
Allow the vehicle to sit for 1-3 hours. Go out and fire it up. It will be flooded, so you may need to use the method of your choosing to get it running. Now, spray a light burst down each barrel one or two times, careful not to kill the engine. Now drive around as normal, and once your fuel runs out, treat the 2nd tank with Sea-Foam.
BENEFITS- A very thorough breakdown of carbon and other sediment deposits in the fueling system, the carburetor, and the combustion chamber.

NEGATIVES- Essentially the same as above, though if done aggressively, damage can result. If you choose to spray into the cylinder, remember, liquids don't compress, and the result of too much liquid could be a catestrophic explosion inside the engine, or you could blow your head gasket/ lift the head. Just use common sense.

After either of the fueling system treatments, I'd recommend changing your fuel filter.

In the crankcase treatment, just remember you may open up pre-existing holes. Also remember that the sediments that would've been blocking the holes do not belong there and are a bad thing for the engine. If it does happen, just go buy a new seal/gasket as if one hole had developed, it just shows a weakness that may get far worse in the future.

I AM NOT RESPONSIBLE FOR ANY DAMAGE CAUSED TO YOUR ENGINE!! Though the only damage I could see being caused, being caused by a stupid act of excessiveness.

Hope this helps!


I must stress the importance of repetitiveness for a complete clean.
The treatment should be done with parts being repeated, such as the float clean and the barrel-soaker.

Recently used this process myself.
To use Sea-Foam in straight liquid form, IN CONJUNCTION with in-the-tank, it must be poured straight in. This is a scary prospect if you understand what Hydro-lock is and what it can do. Liquid does not compress, so if enough enters a cylinder, it can cause the head to lift off the block, or the head gasket to blow, while bending con rods, ruining pistons, and bending valves in the process. It is not to be taken lightly.
So how do you prevent this when using liquids? Moderation. It will burn off, but not so quickly you can just dump the can in. You must gently pour. If you SLOWLY ease into it, you'll find the point that the engine croaks via a flood. Just before that is typically where you want it until you want to kill it.

Okay... I used Sea-Foam for my treatment, and later a blend of Marvel Mystery AND SF.
With the engine hot, gently pur the SF down both barrels, one at a time, gently. After a couple of seconds after finding the point where the engine stumbles, but does not die, adjust to just BARELY enough to kill the engine. You want it to turn off, not blow up. Why having it hot is important is it allows the SF to soak into the carbon and break it down. As the carbon and SF cool, the carbon tries to contract, but the SF won't allow it to, breaking it apart, or at least according to a mechanic/chemical engineer who used to do 3rd party tests of various "De-Gunkers".
Once you've killed the engine, allow it to sit for as long as possible, up to 24 hours. Minimum of an hour is preferred. Then, start the engine, and let it run for about 20 seconds, then jab the throttle a few times, all the way in, so the engine revs up. I never watched the revs in specific, but I don't think past 4k is a good idea for this process. You'll notice the exhaust is normal until you rev, then it turns a nasty color and odor. Why? The sudden jump in RPM's and heat knocks the carbon loose, allowing it to burn and pass.
After maybe 5-10 minutes of running, repeat the process.
You want to repeat this as many times as you can. I did 7 times, but for the 6th and 7th time, I added a twist I wouldn't necessarily recommend.

For those final times, I created a 50/50 mix of SeaFoam and Marvel Mystery Oil and repeated the process. This created MASSIVE amounts of smoke, which had I not done it at night, the neighbors likely would've called us in. Noyt entirely sure this acheived anything.

After you've done the final cycle, go and drive gently for about 3 miles, then drive the ape-dooky out of it for 5. If you did the MMO/SF mix, you'll notice the smoke will continue until about mile 6. Not so great when driving the roads in broad day.

After I did this most previous treatment, the cylinder walls were shiny mirror finish inside the sparker holes and the piston crowns were gently shiny, but not mirror. I did this in conjunction with a valve job and brake job. After the entire process, I attained 35 and 41 mpg readings on a 200 mile each way road trip. The previous same trip got me 27 before (much before).

NOTE- If you guys want, I can re-write this for generic use. I wrote it with a bit of a 3AC bias above, a few years ago. Just let me know.
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