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Concise M272 Seafoam DIY

8739 Views 5 Replies 5 Participants Last post by  Chris toy 1989
Hey guys, first post here. Have owned my E350 for coming up on 4 years now, so as I ticked over 60k miles I'm starting to get some maintenance work in and keep it running just as great as it did the first 60k.
I'll preface this post by saying I know seafoam elicits some split reactions, but as I have had nothing but great results with it, I chose to go this route however won't send any guarantees your way. Also with the M272's having DI, carbon buildup is a bit of concern for me personally.

So for those still interested, here's a quick rundown.

Go for a short drive before you get started and get your engine up to temp and start the following:

1) Slide the air intakes off from their housing
2) Pop the cosmetic cover off, theres two parts to it and its all clipped in, no screws or bolts
3) Slide the metal connector off of the back of the cosmetic cover near the firewall and it should come right out. (Now would be a good time to replace those air filters as well)
4) Locate the MAF Sensor/Throttle body, it is towards the back where that metal connector was, I have included a picture with it circled.
5) Using the aerosol Seafoam spray, take the red connector piece that comes with the bottle and spray so that the connector is going past the the MAF sensor and directly into the throttle body. I had a friend keeping the revs at 1000-2000 while I simultaneously sprayed it in as to not have it choke out.
6) It will take 4-5 minutes to empty out the bottle, my thumb got tired so I had maybe a 1/4 bottle left, still plenty to get the job done.
7) Car off, let it sit 30 minutes.
8) Come back and you'll want to rev it out a bit, then go for a spirited drive. Here is a video of my car on initial startup.

*9) Initially when I came back, the engine was idling a bit rough and I got a CEL for a misfire on my OBDII reader, which I was not surprised about. I shut down the car after revv'ing it for a minute or two and let it sit another 30 mins, came back and light was gone. Went for a drive and got some massive smoke. I think some carbon likely got knocked loose onto one of the spark plugs.
*10) As I always do after seafoam, I highly recommend getting an oil change within 300-500miles after treatment. I will also be getting new plugs at this time, hence my choice to seafoam now.

How to replace Mass Air Flow (MAF) Sensor Mercedes Benz V6 V8 - Mercedes Medic Here is a link that further details how to access your MAF/Throttle body.

Overall, I'm very happy. The idle is silent and the engine is singing again in the upper rev range. Good luck and hoped this helped.


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Fantastic first post!

Welcome to the club.

I'll be adding this DIY to the encyclopedia.
I just did this and had a good result. Seafoam won't hurt your car. It's all mild hydrocarbons. My car had a CEL and a rough idle at first,
Probably because the engine computer shut down one of the cylinders. The idea with this job is to clean the tops of the valves.
How the he'll do I start a fresh post. Desperately need my car to run in the near future and no one can finure it out. Thanks in advance
How the he'll do I start a fresh post. Desperately need my car to run in the near future and no one can finure it out. Thanks in advance
Welcome to the Forum and thanks for filling out your profile :)

1) Near the top of the page below the BenzWorld.Org header, click "FORUM"
2) Scroll down to and click "W124 E,CE,D,TD Class" for your 1990 300E
3) Above "TOPIC / AUTHOR", click > "Post New Thread"
Thanks a lot. Just made my first post. Let's see if the knowledge is waitingoing within the forums to get her running again
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