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Scared of Seafoam...

1915 Views 30 Replies 19 Participants Last post by  Dijital357
Hey guys I've been searching for hours about seafoam and still haven't came up with a straight answer.. People say that it messes up the O2 sensor and others say it cleans it... Other people say it makes the engine worse for higher mileage engines, while others say it made their engine almost "new" again.
I have a early 92 model NA with 200k+ miles on my car and i just started having some high idle issues starting November/December... I want to try to seafoam my engine, but after searching, there are too many mixed results.. I want to know if anyone with a HIGH mileage engine has ran Seafoam through their car recently and the outcome..
I only plan on running it through the throttle body, but I am not sure of what is the safer method.. Some people say through the vaccum lines with the liquid seafoam.. Others say with the spray seafoam through the throttle body.. Somebody please help me out, my eyes can't take reading all those seafoam threads over again lol.. Thanks in advance!
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just dont do it, the cons out weight the pro's of it :)
I'd say it's a 50/50 proposition. I've owned two cars that I 've used Seafoam on - a '91 Celica (5SFE) with ~188k miles, and my '91 MR2 n/a with 195k miles. On my Celica, i had no issue with any additional burning oil. The O2 sensor may have been ruined, but it was a piece-of-junk Bosch unit anyway. However, I do not recall the gas mileage dropping any, so I don't think Seafoam adversely afffected it anyway. In addition, Seafoam did clean up my idle very well.

On the MR2, I can't really say. I do have an issue with losing lots of oil somehow (not through leaks), but that seems to have been an issue before the Seafoam. With my celica, I didn't know Seafoam could foul up the O2 sensor, so this time around I temporarily removed the sensor. Again Seaofoam cleaned my idle very well.

Edit: Both times I used a vacuum hose to suck the fluid in. I had a cup and I used the hose to "sip" it in. I used the hose for the PCV (the hose that connects to your valave cover).
No problems on my 94. I don't really recommend letting it sit in the cylinders like some people do.. and I would NOT put it in my oil. Small amounts over time should clean out the engine good.
If you want to clean out the intake manifold and TB, you could just spray carb cleaner into the TB with the engine running.
used it X car and the o2 sensor got really really really clogged up.
Change your o2 to a spare one before doing it.

Theyre "o2 safe", but all the cloggage will probably have affect on its ability to do what it does best. ;)
i did not find that it clogged my O2 sensor or anything. just to be safe maybe switch to a blown one you have lying around or something...
You will need to replace the spark plugs, the oil/oil filter,a nd likely the O2 sensor after you do the seafoam, but I have found no adverse problems to doing it on my 170k+ mile 2. In fact it idled better afterwards.

Anyway, its always fun to restart the car after you let it sit for 20 miutes then drive it down the street. Everyone looks at you like you have a super-beater because of the CLOUDS of black smoke that come out of the exhaust.

I say do it. DO NOT run it through your oil though. only intake/vacuum lines. In a car with the mileage yours has the oil sludge in the crankcase is likely sealing up some gasket leaks. If you were to seafoam the crankcase by putting it in your oil then you will most likely start leaking oil.

Does it benefit more using Seafoam through the vaccum line or should i just use TB cleaner and spray through the TB with the car running.. Also, if i spray the TB cleaner through with the car running, is there a chance of messing up my plugs and O2 sensor like with seafoam? Thank you all for your responses!
Yes. basically the seafoam breaks up the carbon build up in your intake and gets it out. that carbon is what fouls the O2 sensor and spark plugs. Whether you use the liquid or spray the same will result.

You HAVE to have the car running whether or not you spray it or use the vacuum line.

basically the procedures are as follows for the liquid:

All of this is done on an engine that is at operating temp.

Use a vacuum line to suck the liquid out of the container, and your free hand, or a friend, to keep engine from dying. You will need to rev up the engine to keep it running. A little bit of black smoke will come out while you are doing this. The idea is to keep the engine running as you slowly suck liquid through the vacuum line. You do not want to let the engine stall while doing this. When the bottle reaches about 2/3's empty you want to rev the engine up to like 3 grand and suck ALL of the remaining liquid in at once causing the engine to stall out. When it dies, let it sit for at least 5 minutes. i usually wait 20. Then start the car back up. It wont be easy at first, and will likely take a little help from your right foot to keep it going for the first 10 seconds or so. Then put it in gear and beat the piss out of the car for a few minutes. Lots of high revs, lots of acceleration. And take a moment to look out your rear view mirror as people behind you disappear in your smoke cloud.

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oh, and be SURE to do this ALL outside. i did it in a parking garage with my Grand Prix and there was a cloud of smoke in the garage for a few days. Then there was a layer of carbon on EVERYTHING in the garage. It pissed off a lot of my neighbors. :smile:

it wont necessarily foul the plugs or O2 sensor... it *can* happen...but not always. just make sure you take the car out for a good long spin afterwards to burn everything off. plugs are self-cleaning.
Seafoam is 100% pure petroleum, so it cleans AND lubricates. A lot of other cleaners have acetone and alcohol with petroleum distillates. You shouldn't have issues.

If you're worried, then use a small amount, test your resutls, and use it every 2-3000 miles or so.
if you stall your car out with the seafoam you do run a chance of hydrolocking it, i would not recomend stalling it out.
I did the seafoam and it ruined my O2 sensor. I probably needed another one soon anyhow so I didn't care all that much. My car had about 115,000 miles at the time. I ran it in the gas tank, crankcase, and TB, however, I would not use it in the crankcase if I were to do it again. Also, to agree w/ Dumbscout, I would not let the engine stall at all during the procedure. Be nice and just let it sip.
Dumbscout said:
if you stall your car out with the seafoam you do run a chance of hydrolocking it, i would not recomend stalling it out.
there really isnt any risk of that. you are supposed to stall it out with the seafoam. same with many top-engine cleaners. BG top engine cleaner says the same thing.
When your running to the end of the seafoam your suposed to dump it all in to stall it out. It even says so on the can. I have 200+ on my mr2 and i ran it through the gas tank, crankcase, and intake. No issues my oil consumption is the same as it was before a quart for every 2.5k miles. No serious oil problems but thats just me.

^^^ hey greg, where did you pick up the seafoam from?
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