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Seafoam in Vacuum lines

Hey everyone, I picked up a bottle of Seafoam at the car store today (sale) and I was planning on putting it in the vacuum line. Will this make any improvements in engine quality? And above all, is it safe in my 2002 Accord? It has a 4 cylinder engine with vtec. I was going to use the portion of the vacuum that comes off of the brake booster. Thanks in advance!

Is this listed on the lable? Why do this? If you’re going to this trouble, you might as well use a de-carboning cleaner, like the one sold at GM dealers. But this is only worthwhile to solve a problem.

Seafoam is sold as a decarbonizing cleaner, and sending it thru a vacuum port is the method.

It will certainly burn some carbon out of the intake. Will it help anything? Maybe, maybe not.

Yup, seafoam says it can be used in the vacuum lines. You pour about 1/3 pint into the engine’s lines while running, shut the car off, then let it sit. When you start it up again, there is a great deal of white smoke that comes from the tailpipe. I’ve never heard of anyone having a bad experience with it though. A friend of mine has done it several times on his vehicle. It apparently cures a rough idle (something that is plaguing my car, it comes and goes) I thought I might give it a shot if it is safe.

The key to it being safe is how fast you add it (way too fast could hydrolock it). I wouldn’t use the brake booster, you want a thin vacuum line to slow down the treatment. Might have your friend help you do it.

Alright, so I went ahead and did it. I put about a third of the can through the vacuum line. Let it sit, and started it up. A nice plume of white smoke came out of the tailpipe. BUT, the car actually runs smoother! I didn’t believe it at first, I thought it was snakeoil, but I’ll be darned, the stuff works! The idle is remarkably smoother. I highly suggest it.