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      11-12-2011, 10:02 PM   #1
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Drives: 2008 328i
Join Date: Nov 2011
Location: Austin, Texas

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DIY: Seafoaming an N52

So you want to Seafoam your N52 engine? Well you can't do it like normal people, because we don't have the appropriate vacuum lines. Ordinary Seafoam is out; you need to get the Seafoam Spray.

The Seafoam website has a neat how-to. Basically, it works by spraying it directly at the throttle plate while slightly revving the engine for a couple of minutes, letting the car set, and then driving your Bimmer around like you stole it.

So if it's so easy, why am I posting this? There seems to be some resistance to doing ordinary things (like Seafom) to our engines. A DIY will show that it can be done, and that it won't kill the engine or do anything awful. Second, while accessing the throttle body is a piece of cake on most cars, my experience under the hood of my 328i tells me that numerous engineers in Munich really do not want us to access our throttle bodies. Like getting to our spark plugs, it's not hard, it just has a lot more steps than should be involved.

Tools Needed
  • 10 mm socket
  • 6 mm socket
  • Wife
  • Can of Seafoam Spray (with included spray tube)

Here is the left side of the engine. There are two clamps on the air intake boot; we're going to be undoing the one farthest in the back, which connects the boot to the throttle body. This will first require moving some stuff.

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Step 1: Use the 10 mm socket to undo the nuts holding down the power steering fluid reservoir.

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Step 2: Lift the power steering fluid reservoir off of the bolts and set it somewhere where it will remain upright, but out of your way.

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Step 3: There are these hoses in the back that will also get in the way. Grab them by this rubber thingy, and pull up on the rubber thingy until it is no longer holding the hoses to a metal doohickey. It's not necessary to move the hoses anywhere in particular, they just need to be able to freely move.

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Step 4: That black plastic bar that carries the hoses across over the engine - it may also get in the way. I pulled it out, but that may not have been necessary.

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Step 5: The clamp that you need to loosen - the screw for it faces away from you. It needs a 6 mm socket. I promise you I got a normal socket driver (no extension) back there and was able to loosen this screw. To make reassembly easier (i.e. I didn't do this and later regretted it), loosen the screw the point where the clamp can be slid to your right, up the boot and out of the groove where it normally lives.

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Step 6: Tug, wiggle, and pull the boot until it comes off of the throttle body.

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Here are some pictures of the Seafoam Spray, its spray tube, and the instructions on the back:

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Step 7: Measure how far it is from the lip of the throttle body to the throttle plate. The Seafoam says to cut the spray tube so that it will end about 1/4" before the throttle plate.

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Step 8: Cut the spray tube. Here's what mine looked like:

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Step 9: Hook the small end of the spray tube inside the throttle body and put the boot back in place enough to hold it there. You won't need to put the boot all the way back on, but bear in mind that if it comes off your engine will die.

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Step 10: Insert wife into driver's seat.

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Step 11: Order wife to maintain rpms between 1500 and 1700 (can says 500 to 1000 over idle).

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Step 12: Attach Seafoam can to loose end of spray hose. You'll want to use two hands for this, one to hold the can and press the button, the other to hold the tube securely in place. Shortly after I took this picture, I sprayed the Seafoam without using a second hand to hold the tube in place, and the pressure from the Seafoam caused the tube to come out and I sprayed Seafoam all over the outside of my engine. Anyhow, the can says to spray until half the can is gone; this takes two, three, maybe four minutes. Hope you brought a radio, cause it's kinda unpleasant standing there with the engine revving and your head under the hood, just holding a can.

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Step 13: Turn the car off. The can says to wait 5 minutes; I restarted the car after 5 minutes and didn't get much smoke. I turned it off and waited another 10, at which point I got the smoke show you see below. At any rate, use this time to put everything back into place that you took apart in the first few steps.

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That's more smoke than I anticipated, considering the engine is only at 52,500 miles, 90%+ of which was driven on Shell 93.

Step 14: Drive like a mad man until the smoke stops coming out. This took me about 4 or 5 minutes.

I don't think using Seafoam in the intake like this is as effective using Seafoam in the crankcase before an oil change, but it plainly does something (with prior cars, I've used repeated applications of Seafoam to see if the smoke was just the product, and I got decreasing amounts of smoke with each application, which would be consistent with Seafoam's claims that it's removing carbon from the engine) and it's never hurt a car that I've used it on. And the big cloud of smoke is kinda fun.
2008 328i, Black Sapphire, Sports, Premium, AT with the flappy paddles