Of all the magic additives out there, SeaFoam has a lot of believers. It is cheap as well as easy to use, and just may be worth a try.By Mark Garrett – November 16, 2015

This article applies to the Jeep Wrangler JK (2007-Present).

SeaFoam appears to actually work in both cleaning the crankcase and fuel system. Modern oils should do an excellent job of keeping your crankcase clean, but if you have a used vehicle, it may take care of past sins. Keeping your crankcase extra clean is not a bad idea. Modern fuels are the same, but fuel injectors really need to be clean to perform correctly, so a cleaner for the fuel system is actually a good idea. SeaFoam may be the solution for your idling or performance issue, so let’s give it a try.

Materials Needed

  • Plastic funnel for gas tank
  • Small plastic funnel
  • SeaFoam

Step 1 – Add to fuel tank

SeaFoam suggests using one can of treatment for up to 16 gallons of fuel.

Figure 1. SeaFoam cleaner.

The more you use, the better it works; for instance, you can add one can to eight gallons of fuel. If you are also adding it to your engine, it is fine to add 1/2 can to the tank and 1/2 can to the engine. Remove the gas cap and pour the SeaFoam into the tank using a funnel. After adding it to your gas tank, just drive as usual to let the SeaFoam circulate throughout the fuel system.

Figure 2. Add to fuel tank.

Pro Tip

The general consensus is adding a can to your tank every oil change works well.

Step 2 – Add to intake

If you are having knocking issues or the engine is running rough, the quickest results happen if you add the SeaFoam through a vacuum line on the engine. Though it is quicker, you have to use caution since you are adding a liquid to the combustion chamber that is made to handle vapor. Most Jeep people add the SeaFoam through the vacuum brake booster hose.

Figure 3. Booster vacuum hose.

Remove the end of the hose shown in Figure 3. Start the engine and allow to run. It may idle rough since the vacuum hose is disconnected. Using a small funnel, slowly poor the SeaFoam in the hose. The engine will probably run rough and may make some noise, but continue to pour 1/3 of the can in. Shut the engine off for 30 minutes or so. Now start your engine and allow to idle. It will smoke like crazy since all of the stuff is burning out of the engine. You can rev it up after a bit and let the smoke die down.

Figure 4. Smoke from exhaust after restarting.

It is fine to drive your Jeep now and continue to let the stuff from your engine get cleaned out. A lot of people say their Jeep runs better and smoother after treatment.

Pro Tip

Don’t be tempted to stick the hose into the can, since taking a slug of liquid could hydro lock the engine.

Step 3 – Add to engine oil

SeaFoam will clean out your crankcase whether there is a little buildup or a lot. SeaFoam suggests using one to 1-1/2 ounces of additive to one quart of oil. One can should be just about right for your Jeep. Pour it into the oil filler cap and replace it.

Figure 5. Add SeaFoam to engine oil filler.

After putting SeaFoam into the engine oil, most people feel that the oil should be changed after a few hundred miles. The oil should look more dirty than usual after and deposits are washed out by the additive.

Pro Tip

Some fellow Jeep enthusiasts say that Mopar Combustion Chamber Cleaner, Chevron Techron, Marvel Mystery Oil and other additives work just as well. Personally, SeaFoam is the only cleaner that I have seen work, but the other may work well.

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