How to Add Seafoam to your Engine
This is a step-by-step tutorial with photos on what to do with that can of Seafoam you just bought.
Do you have a 2001+ V70, XC70, S60? The intake is different. You’ll want to use How to Use Seafoam on a 2001+ Volvo.
I did the traditional 1/3 in crankcase, 1/3 in gas tank and 1/3 in intake yesterday.
1/3 in gas tank: this is self-explanatory. Use a funnel.
1/3 in crankcase: where your oil goes. Note you must change oil within a few tens of miles after adding Seafoam to your crankcase. Your engine and oil is not designed to run with Seafoam in it for an extended period. I drove 5 or so hard miles after adding the Seafoam.
1/3 in intake: this is the tricky one.
First, pour 1/3 can of Seafoam into a clean glass container, preferable something durable like this Coke bottle. The point is you want to be able to see what you’re doing with the hose.
Second, drive to a desolate area, leave the car on, and pop the hood.
Take a cap of one off the vacuum tree nozzles.
Attach a hose, at lease 2 feet (.6 meter) in length. Have a “P2” Volvo, meaning a 2001+ V70 or S60 or XC70? You don’t have a vacuum tree! Luckily, MVS contributor Velorider shows us how to use the brake booster line to suck Seafoam into the intake on P2 Volvos.
Then slowly move the hose down to the liquid and vacuum it up. The CRUCIAL thing here is to not submerge the tip of the hose in the Seafoam. Keep it at the top so that it pulls air and liquid at the same time. Like kids do with their straws with a drink when they want to annoy you. Idle should dip a little, but not die. Seafoam instructions — I believe — say to kill the engine by sucking in too much. I am wary of that. Hydrolocking your engine is a very real danger here. I’m pretty sure a member here did that very thing doing this very procedure about a year ago. If anyone knows the thread, please post it in a reply below.
Why tempt fate? Take your time. I took about 5 minutes to suck all the liquid with the hose. Idle dipped and recovered over and over. This is when the smoke begins.
The smoke is why you want to go to a desolate industrial area — you will annoy people.
Then go for a hard drive for 5 or 10 miles. Smoke will pour out of your exhaust at first, then after a few miles will clear up to normal.